I was interested in your Q&A about fruit juices affecting medi- cations (April). What about tomato juice?
Answer : We checked in again with David G. Bailey, PhD, a professor of clinical phar-macology at Western Ontario University, who found that fruit juices (including orange, apple and grapefruit) consumed within two hours of taking certain medications dramati-cally weakened the drugs’ effectiveness. Bailey and colleagues did not test tomato juice spe-cifically, but he says, “Fruits and vegetables contain a lot of flavonoids. We have been able to show that one of the important active in-gredients in grapefruit juice is naringin, which is a flavonoid. Thus, it is possible, but not yet shown, that another member of this family would also impair the absorption of certain drugs. Naringin is not found in tomato juice, however. Based on our current understanding, I would suggest that the way to get the most reliable effect is to take medications with a glass of water on an empty stomach at least two hours before eating, if possible
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I have read that eggs from free-range chick-ens have less cholesterol than from chickens confined in pens. Is this true?
Answer : Given the growing popularity of “free-range” chickens, surprisingly little scientific research has been done on the nutritional differences, if any, of these chick-ens or their eggs compared to chickens raised in more confined conditions. A 2007 study conducted by Mother Earth News magazine, but not published in a peer-reviewed scientific journal, did find that eggs from free-range chickens contained one-third less dietary cholesterol and (more important for blood cho-lesterol levels such as LDL) one-quarter less saturated fat. The eggs from free-range birds were significantly higher in vitamin A, vitamin E and beta-carotene and contained twic omega-3 fatty acids.
Several other studies have shown that free-range eggs are superior in one or another nutrient, but few have produced similar results regarding cholesterol and saturated fat. A 1999 Penn State University study did report that eggs from free-range (or “pastured”) birds had 10% less total fat and 34% less dietary cholesterol compared to the standard USDA data on supermarket eggs. (The same study also tested free-range chicken meat, and found it to have 30% less saturated fat than the USDA standard.)
The American Egg Board, which repre-sents the conventional egg industry, maintains that “the nutrient content of eggs is not af-fected by whether hens are raised free-range or in floor or cage operations.” The industry’s Egg Nutrition Council says, “Barring special diets or breeds, egg nutrients are most likely similar for egg-laying hens, no matter how they are raised.”
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What are the benefits
or cons of bee pollen
and natural honey?
Answer : For a quick sense of the commercial versus
scientific status of these popular
products, compare the results of a Google
search for “bee pollen health benefits”—over
80,000 hits—
to those of a
similar search
of the government’s
exhaustive
PubMed
database of
medical research: 121 results, most of only
peripheral relevance to human health. “Bee
pollen” is actually a misnomer: It’s simply the
pollen from flowers that bees collect and bring
back to the hive. “Natural” or “raw” honey may
contain resins from propolis, a sort of “bee
glue” also touted for health benefits.
For centuries, various bee products have
been touted as aiding athletic and sexual performance,
fighting infections, preventing cancer
and promoting both weight loss and weight
gain. The Federal Trade Commission has frequently
cracked down on vendors of bee pollen
and similar products for unsubstantiated claims
ranging from treating allergies to arthritis,
fatigue to arteriosclerosis.
A handful of studies have suggested that
bee pollen may have some benefit against
chronic prostatitis (a disease of the prostate)
and menopausal symptoms, and that propolis
may help dental hypersensitivity and possess
antibacterial effects. A few studies have found
“natural” honey superior to processed honey in
cholesterol and blood-sugar effects. Honey—
“natural” or otherwise—has been studied for
blood-sugar control and insulin sensitivity (versus
other sweeteners), as a cough suppressant
and as an immune-system booster. None of the
evidence for any of these claims is strong
enough to support the use of any bee-related
products for health reasons alone. If you like a little honey in your tea, that’s fine—but keep in
mind that you’re adding about 20 calories per
teaspoon.
Potential downsides to bee products
include the possibility of dangerous allergic
reactions and potential contaminants ranging
from heavy metals to pesticides. Bee pollen has
been linked to liver damage in isolated cases.
And children younger than 12 months should
never be fed any kind of honey because of the
risk of infant botulism.
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I am a subscriber who
is a mild diabetic. My
wife serves grape tomatoes
at dinner, which
are much tastier than regular
tomatoes this time of year. I
would like your input on the
sugar content and nutritional
difference between grape and
regular tomatoes.
Answer : Overall, the nutritional differences
between types of tomatoes—including
grape, cherry and other bite-sized varieties,
as well as plum, Roma and other larger
options—are quite small, probably less than the
variations by season and producer within any
one type. We checked with two leading producers
of grape tomatoes and got slightly different
nutritional data. In general, though, grape
tomatoes are similar to regular tomatoes in
calories, carbohydrates, dietary fiber and sugar
content. Both grape and regular tomatoes supply
about 25% of your daily vitamin A and 32%
of daily vitamin C. A cup of either grape or regular
tomatoes has a glycemic load (see story
on page 1) of about 2, so neither choice will
significantly raise blood sugar. It may be that
the grape tomatoes you’re enjoying have a
higher sugar content and sweeter taste than
the currently available regular tomatoes—but
not necessarily different from regular tomatoes
found later in the season.
One difference noted in 2002 research in
the Journal of Agricultural and Food Chemistry is
that cherry tomatoes have higher levels of
antioxidants than normal-sized tomatoes; this
would likely also be true for the similar “grape”
tomatoes. The research also reported that riper
cherry tomatoes have higher levels of
carotenoids and antioxidants than those picked
when less ripe.
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Is it true that research
has shown that drinking
diet drinks can
cause weight gain? Do
you recommend that someone
wishing to lose weight (or anyone
else) should avoid them?
Answer : Susan B. Roberts, PhD, director of Tufts’
HNRCA Energy Metabolism Laboratory
and author of The I Diet , replies: “My clinical observation is
that for some people they help and for others
they don’t. It depends on how you use them. If
they are a substitute for with-sugar drinks and
over time you look on them as a bridge to a
low-sugar and low-sweet diet, that is a great
way to go in my opinion! Weight loss is hard
for many people and you need to use all the
help you can.”
|
Can levels of the
“good” HDL cholesterol
be too high?
Answer : Alice H. Lichtenstein, DSc, director of
Tufts’ HNRCA Cardiovascular Nutrition
Laboratory, replies, “To my knowledge,
there are no data to indicate that HDL can be
too high.” The National Heart, Lung and Blood
Institute’s (NHLBI) National Choles terol
Education Program recommends HDL levels of
60 mg/dL or greater for protection against cardiovascular
disease.
|
I am living alone and
very often make a little
too much food for one
meal. I am wondering
if much nutrition is lost when I
reheat a veggie for a second
night, which I often do.
Answer : Alice H. Lichtenstein, DSc, director of
Tufts’ HNRCA Cardiovascular Nutrition
Laboratory, says that microwaving or
gentle reheating in a pan shouldn’t do much
damage to the nutrients in previously cooked
vegetables. (This is another good reason,
though, not to overcook vegetables the first
time—they’ll stand up better to reheating.)
Another option she suggests is to add cold
cooked veggies to perk up a salad.
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Are green bananas safe
to eat? Are they as
good for you as ripe
bananas?
Answer : Contrary to popular belief, eating green
bananas won’t make you sick (unless, of
course, as with other foods, you eat too
many of them), though they may be more difficult
to digest than the ripe fruit. Fully ripened
bananas may have developed slightly more
antioxidants, but otherwise the nutritional profiles
of green and ripe bananas are quite similar.
In fact, green bananas might have a few
advantages: As bananas ripen, they convert
starches into sugars, so greener fruit are less
sweet and affect your blood sugar less. Green
bananas also contain more short-chain fatty
acids (SCFAs), which are indigestible to
humans but nourishing to the cells that line
your intestines. Various studies have shown
improvements in intestinal function from consuming
SCFAs in general and green bananas in
particular.
|
I have wondered why
sea salt is so often
touted in recipes.
Considering that our
sea waters are so contaminated
now, is there no concern that
their condensed form, salt,
could be harmful to ingest?
Answer : Unlike regular table salt, which is mined
from rock salt, “sea salt” is produced by
the evaporation of seawater. The concentrated
brine precipitates the salt, which is then
gathered by harvesting machines. Both types of
salt (as well as “kosher salt,” which can be
mined or evaporated from seawater) consist of
sodium chloride, although sea salt may also
contain trace amounts of other minerals that—
adherents say—give it a different taste. Sea salt
typically does not contain added iodine, which
helps prevent goiter. Some purveyors of “purified”
or “synthetic” sea salt do warn that other
brands could contain mercury and other contaminants;
they point out that the waters off
Brittany, in northwestern France, which produce
much of the sea salt popularly sold as
“natural,” are badly polluted. The FDA has not
issued any warnings about adverse health
effects from contaminated sea salt, however,
and in any case it’s unlikely that you’d consume
enough to ingest much pollutants. We
also note that the Environmental Defense Fund,
which among other things monitors and advocates
for the purity of the world’s oceans,
doesn’t hesitate to call for sea salt in recipes on
its web site www.edf.org.
Sea salt can be either fine (similar to table
salt) or coarse (like kosher salt). Because the
larger grains don’t pack as tightly together, a
quarter-teaspoon of coarse sea salt contains
570 milligrams of sodium, compared to 590
milligrams in the same volume of table salt
(and 480 milligrams in kosher salt).
|
I bake some favorite
desserts and recently
switched to wholewheat
pastry flour. Is
whole-wheat pastry flour as
nutritious as regular wholewheat
flour?
Answer : So-called “pastry flour,” also known as
Graham flour, is milled from soft wheat
that’s lower in protein than regular
wheat. The resulting flour weighs less than
standard whole-wheat flour—it takes 1/3 cup to
weigh 30 grams, compared to 1/4 cup of the
same manufacturer’s non-pastry whole-wheat
flour—and has slightly fewer calories by weight
(100 in 30 grams, versus 110). Besides being
lower in protein (3 grams per serving versus 4)
and therefore lower in gluten, whole-wheat
pastry flour is similarly lower in fiber (3 grams
instead of 4). Despite these small nutritional
differences, whole-wheat pastry flour is still a
better choice for cookies, pie crusts and hearty
cakes than all-purpose or cake flour made
from refined wheat.
|
I was interested in your
article about oranges
(January 2010), but I
remember reading that
when I take Cipro I should be
careful of when I drink orange
juice. Is this right?
Answer : It’s commonly known that grapefruit juice
has the potential to boost excessively the
action of many prescription drugs. David
G. Bailey, PhD, a professor of clinical pharmacology
at Western Ontario University who discovered
that grapefruit-drug interaction 20
years ago, recently identified a reverse effect of
some common juices—including orange, apple
and, again, grapefruit juice. The mechanism is
different from that by which grapefruit can
overly enhance the power of drugs (through
deactivating a gastrointestinal enzyme that normally
breaks down medications before absorption
into the bloodstream). In research presented to the American Chemical Society in 2008,
Bailey and colleagues reported that fruit juices
consumed within two hours of taking certain
other medications can decrease their absorption
sufficiently to raise concern for weakened
effectiveness. Currently identified medicines
negatively affected include blood-pressure-lowering
beta blockers (such as atenolol, celiprolol
and talinolol), the allergy treatment medication
fexofenadine, the antibiotic ciprofloxacin and
the anti-cancer drug etoposide. Researchers
believe naringin, the compound that gives
grapefruit its bitter taste, is responsible for a
major portion of the effect in grapefruit juice,
and have identified a naringin-like chemical in
orange juice as well. The findings don’t mean
you have to give up fruit juice, however. Juice
consumed four hours prior to taking medications
had no weakening effect. Bailey advises,
“Take your medications with water, at least two
hours before consuming fruit juices or eating
fruit, if possible on an empty stomach, to prevent
reduced drug absorption.”
|
Do clementines have
the same nutritive
value as oranges?
Answer : Although sometimes called “seedless tangerines,”
the sweet winter treats known
as clementines are actually a variety of
mandarin orange. Traditionally, clementines are
said to be an accidental hybrid discovered by
Father Clément Rodier in his garden in Algeria;
they were introduced into California commercial
agriculture in 1914. Although a clementine
weighs only about half as much as a navel
orange, ounce for ounce they are nutritionally
similar: about the same amount of calories and
potassium, while a navel orange contains slightly
more fiber, vitamin C, calcium and folate per
ounce. At only about 35 calories per fruit,
clementines make an ideal snack.
|
You often report about
research on “processed” meats. But
what exactly does
“processed” meat mean?
Answer : According to the US Department of
Agriculture (USDA), processed meat
products may include, but are not limited
to, bacon, deli/sandwich cuts, frankfurters, salami
and sausage. Such products, derived from
beef, pork, poultry or sheep, are processed
and/or preserved beyond simply cutting, slicing,
grinding, rolling or skewering. For example,
processed meats may be canned, cured, brined
or salted, pickled or smoked. Processed meats
often contain nitrites, added as preservatives,
stabilizers and coloring agents.
|
Is sauerkraut anticarcinogenic?
Answer : Cabbage, from which sauerkraut is made,
is a cruciferous vegetable (like broccoli).
The compounds that give cruciferous
vegetables their sometimes-bitter taste and distinctive
smell help protect the plants from
insects and munching herbivores; when broken
down in the human digestive system, these same compounds may help protect against cancer.
Studies have shown that people who eat
more cruciferous vegetables, including cabbage,
were less likely to develop lung and bladder
cancers.
Sauerkraut specifically contains isothiocyanates,
compounds produced by fermentation
of raw cabbage, which are being studied for
anti-cancer properties. The Polish Women’s
Health Study found that women who ate at least
three servings a week of cabbage and sauerkraut
were significantly less likely to develop
breast cancer than those eating it only once a
week.
|
I enjoyed your Special
Report on “Food and
Your Mood” (January
2010), but wanted to
know more about serotonin. Is it
true that eating foods high in
tryptophan boosts serotonin levels?
What about supplements sold
as “mood enhancers” that are
related to tryptophan?
Answer : Tryptophan is an amino acid found in foods
including poultry, peanuts and seeds, soy
products, dairy, eggs and fish. It’s an essential
amino acid, meaning your body can’t produce it;
you must obtain it from your diet. Popularly, tryptophan
is best known for its supposed power to put
you to sleep after eating too much Thanksgiving
turkey (in reality, all those carbs in the holiday feast
are to blame). The body converts tryptophan into
niacin and into serotonin, a neurotransmitter that
regulates mood, anger and aggression, appetite and some cognitive functions. Antidepressants such
as Prozac and Zoloft are selective serotonin
reuptake inhibitors (SSRIs), which block the reabsorption
of serotonin. When serotonin is converted
to the hormone melatonin, it helps you
sleep—hence the turkey tale.
When you eat foods containing tryptophan,
the body converts some of it to kynurenine,
which ultimately produces niacin. Other tryptophan
gets converted into another intermediate
compound, 5-hydroxy tryptophan (5-HTP).
Tryptophan supplements, once commonly
used for insomnia, depression and anxiety, were
banned in 1989 after toxic contaminants caused
an outbreak of eosiniphilia-myalgia syndrome
(ESS), characterized by muscle and joint pain,
weakness, fever, swelling of limbs and shortness
of breath. Recently, however, supplements of 5-
HTP have appeared on the US market, promoted
for positive mood and appetite control.
To learn more about tryptophan and 5-HTP,
we consulted Erick H. Turner, MD, of the
Portland VA Medical Center in Oregon, who
authored a comprehensive review of the evidence
on 5-HTP and serotonin. “I would argue
that tryptophan is inefficient compared to 5-
HTP,” Dr. Turner replied. “The idea is to get
more serotonin synthesized in the brain. When
you eat tryptophan, first of all, the lion’s share of
it goes down the kynurenine pathway (to make
niacin), and only a minority goes down the serotonin
pathway. With 5-HTP, you’re already
halfway down the serotonin pathway, so it can
only go toward serotonin.
“However, you still have to worry about the
5-HTP being converted to serotonin before it gets
into the brain, in which case you can get side
effects related to serotonin’s action on various
organs (e.g. nausea, flushing). This is not a disadvantage
compared to tryptophan—what little
tryptophan gets to the 5-HTP step will suffer the
same fate. The way to minimize the amount of
5-HTP getting chewed up in the periphery—
before it gets into the brain—is to give a peripheral
decarboxylase inhibitor (PDI), such as carbidopa,
which is available only by prescription.”
Nonetheless, Dr. Turner says it’s plausible 5-
HTP supplementation could be effective in treating
depression and anxiety, “since serotonin is
implicated in anxiety disorders as well as depression
(and many SSRIs are approved for both).”
Eating lots of turkey, however, is unlikely to
significantly improve your mood.
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Since calcium and vitamin
D strengthen bones
and vitamin A weakens
bones, why is all reducedfat
milk fortified with both vitamin
A and vitamin D? And why
is whole milk not?
Answer : Robert M. Russell, MD, professor emeritus
at Tufts’ Friedman School and former
director of the Jean Mayer USDA Human
Nutrition Research Center on Aging, explains:
“It is true that in animals and man vitamin A in
very high (toxic) doses can cause bone demineralization
and a weakening of bones. Also,
there have been some epidemiological studies
that have shown a relationship between vitamin
A intakes above one-and-a-half to two times
the Recommended Dietary Allowance (RDA)
and lower bone density, but this is far from
proven. There are many other published studies
that have not shown this relationship. At any
rate, the vitamin A fortification level of skim
and low-fat milk is low and safe (150 micrograms
in a cup—whereas the RDA for an adult
male is 900 micrograms per day). Low-fat and
skim milk are required by the FDA to be fortified
at this level, as the vitamin A is lost from
the milk when the fat content is lowered (the
baby is thrown out with the bathwater, so to
speak). Whole milk still has plenty of fat and
vitamin A content, which is absorbed well due
to the fat that it travels with.”
|
I have read that pomegranate
juice interferes
with the availability
and absorption of
hypertension medication, in
much the manner that grapefruit
juice does. Is this true? If
so, is the effect diminished by
taking the juice hours before or
after the medication?
Answer : You can drink your pomegranate juice
whenever you like, according to David
J. Greenblatt, MD, professor and chair
of the Department of Pharmacology and
Experimental Therapeutics at Tufts’ School
of Medicine. “Pomegranate juice does not
have the same properties as grapefruit
juice,” Dr. Greenblatt says. “Pomegranate
juice has no effect on the absorption of any
medications, and there is no concern with
taking pomegranate juice with prescription
drugs, regardless of the timing.”
|
I’ve often read in your
newsletter that all fats
contain about 120
calories per tablespoon.
So why does my butter package
say a tablespoon contains only
100 calories?
Answer : The total calories per serving is different
between oil and butter because a
tablespoon of oil contain a full tablespoon
of fat whereas a tablespoon of butter
does not. According to Alice H. Lichtenstein,
DSc, director of Tufts’ HNRCA Cardio -
vascular Nutrition Laboratory, butter is about
20% water, by weight; it also contains some
milk solids. Vegetable oil, however, is 100%
fats, 0% water. A tablespoon of clarified
butter (or “ghee”), which has been heated
to evaporate the water and then skimmed to
remove milk solids, does indeed contain
about 120 calories. Although marginally
lower in calories than a tablespoon of vegetable
oil, that tablespoon of regular butter
also contains 7.3 grams of saturated fat--a
good reason to stick with liquid vegetable
oils that are lower in this key culprit contributing
to unhealthy cholesterol levels.
|
I have osteoporosis, and
my doctor wants me to
take 1,000 IU daily of
vitamin D, along with my
other daily vitamins, which also
contain vitamin D. I calculate
that this would bring my daily
vitamin D total to 2,300 IU. Is
this safe?
Answer : It’s true that vitamin D can be toxic at
extremely high levels and, technically, your
total intake would be above the 2,000 IU daily
Tolerable Upper Intake Level (UL) for vitamin D set
by the Institute of Medicine. An expert panel is currently
reviewing the recommended levels for vitamin
D, however, and may recommend raising the UL as
well as the Adequate Intake (AI); those recommendations
are expected next year. Recent clinical trials
suggest that the safe upper limit for vitamin D may
be as high as 10,000 IU daily. Our advice in the
meantime? Make sure your doctor knows about the
other supplements you’re taking, and see if she
thinks you should switch to a lower-dose vitamin D
supplement. (For more on vitamin D, see our June
2009 Special Report.)
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I’ve noticed that some
cereals contain freezedried
fruit. How does
freeze-dried compare to
fresh fruit in terms of nutrition?
Answer : The practice of freeze-drying foods dates to
the ancient Incas, who would set out their
crops on the slopes of the Andes, where the
foods would freeze and then slowly dry in the low
air pressure at high altitude. Modern freeze-drying,
which employs a vacuum instead of thin mountain
air, was first used for medical products such as
blood plasma and for instant coffee. Nescafé, the
first popular instant coffee, was introduced in 1938
by Nestlé to help Brazil use up a coffee surplus.
Nestlé’s freeze-drying process sparked experiments
with other foods, including fruit. Because freezedried
foods are both long-lasting and lightweight,
they proved ideal for feeding astronauts on space
missions.
According to research presented at the 2006
American Institute for Cancer Research conference,
freeze-dried fruits contain levels of antioxidants almost as high as the fresh originals. Freeze-drying
does, however, seem to damage some fragile
nutrients. Because freeze-dried fruits typically
don’t contain added sugar, as many dried fruits
do, they can be enjoyed “guilt-free,” much like
fresh fruits.
The USDA Nutrition Database has not computed
nutrient values for freeze-dried fruits, but it
does contain data on freeze-dried sweet green
(bell) peppers. A quarter-cup of freeze-dried peppers—
which of course required considerably more
volume of fresh peppers to make—has about the
same amount of calories and vitamin C as a quarter-
cup of fresh peppers; slightly less magnesium,
phosphorus and potassium; roughly two-thirds the
carbohydrates, total sugars, vitamin A and lutein;
and about half the fiber and calcium.
|
Given the recent
reports about bacterial
contamination in nuts,
does it make sense to
heat nuts to a certain temperature
before eating? This works
for eggs and meat, why not
nuts?
Answer : We checked your nut idea with Helen
Rasmussen, PhD, MS, RD, an instructor at
Tufts’ Friedman School and Senior Research
Dietitian at the HNRCA Metabolic Research Unit.
Happily, Rasmussen has a Tufts University School of
Medicine student, Eva Litvak, working with her who
could dig into this question in-depth.
Bacterial contamination of food can happen at
any stage of food processing, from growth, to harvest,
to storage, to packaging, to its final preparation.
Any time foods are stored within a certain
range of temperatures that are optimal for bacterial
growth, the chances of contamination also
increase. Eggs and raw animal products are much
more likely to be exposed to bacteria during processing
and must always be heated to appropriate
temperatures during cooking. Though nuts may also
be exposed to bacteria, most are dry-roasted after
harvest, which kills bacteria at that stage of processing.
Because of their high fat and low moisture
content, however, heat-processing nuts may be a
lengthy and unreliable method of preventing contamination
at home.
For more information, see the National
Institutes of Health website on “Bacteria and
Foodborne Illness” digestive.niddk. nih.gov/
ddiseases/pubs/bacteria.
|
A friend in India
claims that it is not
advisable to eat fruit at
the end of a meal,
because the nutritional value
of the fruit is diluted when it
comes on top of other food. Is
there any truth to this?
Answer : Tufts’ Rasmussen and Litvak again have the
answer: After eating a meal, all the food we
have consumed begins to break down in the stomach, where gastric secretions start to separate
foods into the nutrients that our bodies can
absorb. This food sits in our stomachs for minutes
to hours as it is churned and emulsified.
Then the stomach gradually empties its contents
into our small intestine, where the absorption of
nutrients begins. At that point, everything we
have eaten during a meal has already been
mixed together quite thoroughly. Whether you
choose to eat fruit at the beginning or at the end
of a meal will not diminish its nutritional value.
The fruit is not adversely affected by any other
foods it is eaten with. Our bodies are very good
at taking all the nutrients we need from the
foods we eat, regardless of the order in which
we eat them.
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After getting so many different
answers, can you please tell
me how bad is aspartame? I
like chewing gum sweetened
with it—two or three pieces a day—
and people tell me I should cut down
because aspartame is bad.
Answer : Keep chewing and stop worrying.
The American Dietetic
Association (ADA) recently
completed a thorough review of the scientific
evidence about aspartame and
health (see NewsBites, August 2009).
The findings debunked myths about aspartame, including the notion that it
makes you hungrier (a so-called
“rebound” effect) and that it somehow
causes weight gain. The ADA also
found no evidence for various Internet
myths and “urban legends” about the
sweetener, concluding: “Aspartame consumption
is not associated with adverse
effects in the general population.”
Those conclusions echo the position
of the US Food and Drug Admini -
stration (FDA), which states: “Since it
was first approved for use in the
United States, the safety of aspartame
has been questioned by some. To date,
however, the agency has not been presented
with scientific information that
would support a change in our conclusions
about the safety of aspartame.
Those conclusions are based on a
detailed review of a large body of
information, including more than 100
toxicological and clinical studies
regarding the sweetener’s safety.”
|
Besides being kosher for
religious purposes, what’s
the difference between
kosher salt and other salt?
Answer : AKosher salt, like most supermarket sea
salt, is much coarser-grained than ordinary
table salt. That makes it take up
more volume for the same amount of weight,
so you may need to adjust the amount used if a
recipe calls for regular salt; check the koshersalt
box for a conversion factor. (Morton, for
example, says to use the same amount of
kosher salt as specified for table salt, except in
recipes requiring more than a quarter-cup; then
you should add an extra tablespoon of kosher
salt for every quarter-cup.)
Kosher salt does not dissolve as quickly as
table salt, making it useful for giving a salty
“feel” to the exterior of foods without using as
much salt. In fact, this property is actually the
reason for the name “kosher,” because kosher
salt can be used to draw the blood out of meat,
as prescribed by Jewish law. Almost all salt,
including table salt, is kosher certified. Unlike
most table salt, kosher salt is not iodized and is
commonly free of other additives as well.
(Morton kosher salt, however, contains yellow
prussiate of soda—sodium ferrocyanide—as an
anti-caking agent.)
As for sodium content, if you substitute
kosher salt one-for-one for table salt, you will
slightly decrease your sodium intake because of
kosher salt’s greater volume: One teaspoon
contains 1,920 milligrams of sodium, compared
to 2,325 milligrams in table salt. By weight,
however, both kosher and table salt contain
about 400 milligrams of sodium per gram.
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Is it contraindicated for
individuals at risk of
developing calcium
oxalate kidney stones to
take vitamin D3 supplements?
Answer : Lesley Stevens, MD, MS, an assistant professor
of medicine at Tufts, replies,
“Vitamin D supplements are not necessarily contraindicated but would depend on
why the person is at risk for the development
of kidney stones. I suggest speaking to their
doctor first.” That’s good advice for most supplements
if you’re at risk for kidney stones,
according to the National Kidney Foundation,
which suggests, “Check with your doctor or
dietitian for advice on the use of vitamin C,
vitamin D, fish liver oils or mineral supplements
containing calcium since some supplements
can increase the chances of stone formation
in some people.”
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In your May issue you
illustrated the “radura”
sign for food treated by
irradiation. A caterer told
me all pork is irradiated to prevent
trichinosis; that is why it can
be served when the meat is still
pink inside. However, pork sold in
grocery stores does not have this
sign on it. Is it true that pork is
safe to eat when cooked this way?
I was taught to cook pork until it
was gray inside.
Answer : You might want to switch caterers.
Trichinosis is caused by ingestion of the
Trichinella spiralis parasite, also known as
trichina. According to the US Department of
Agriculture (USDA), “Irradiation has been
approved for use on pork by FDA and USDA/
FSIS in low-doses (to control trichina). Treated
pork would not be sterile and would still need to
be handled safely. Trichinella could be alive but
would be unable to reproduce. Packages of irradiated
pork must be labeled with the irradiation
logo as well as the words ‘Treated with Irradiation’
or ‘Treated by Irradiation’ so they would be easily
recognizable at the store.” So it’s not true that all
pork has been irradiated, and pork that has been
irradiated must bear the “radura” sign plus this
labeling.
That doesn’t mean, however, you need to
cook pork until it’s gray inside. Meat color, in fact,
is not a reliable indicator of temperature and food
safety; it’s better to invest in a good meat thermometer.
Although the Centers for Disease
Control and Prevention (CDC) continues to recommend
cooking to 170 degrees to prevent trichinosis,
the USDA states, “Much progress has been
made in reducing trichinosis in grain-fed hogs,
and human cases have greatly declined since
1950. Today’s pork can be enjoyed when cooked
to an internal temperature of 160 degrees.” That
temperature—at which pork might still appear
slightly pinkish—is also hot enough to kill foodborne
bacteria such as E. coli and salmonella. To
learn more about pork preparation and safety, see www.fsis.usda.gov/Factsheets/Pork_From_Farm_to_Table/index.asp.
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I have long read recommendations
of low-fat
milk. How about powdered
milk? I have used
it for about 50 years—mixed
extra rich—for the vitamin D,
calcium and no fat.
Answer : Just like regular milk, powdered or “dry”
milk comes in different types. The most
important difference is whether the milk
is nonfat or whole. If you’re reconstituting
whole powdered milk, you’re getting 159 calories
and 5.3 grams of saturated fat from every
quarter-cup of powder. But if you stick to nonfat
dry milk, a quarter-cup of powder contains
just 109 calories and only trace amounts of fat,
while still containing 100 IU of vitamin D and
377 milligrams of calcium—amounts similar to
ordinary skim milk. Mixing dry milk “extra rich”
would indeed boost the nutrients (as well as
the calories)—just make sure you’re buying the
nonfat variety, or it would truly be “extra rich”
in fat and calories.
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I take a multivitamin
with my morning cup
of tea. Do I need to be
worried that the tea
might block the absorption of
the vitamins?
Answer : In general, there’s no need to be concerned
about tea blocking the absorption
of vitamins or other nutrients, according
to Jeffrey B. Blumberg, PhD, director of the
Antioxidants Research Laboratory at Tufts’ Jean
Mayer USDA Human Nutrition Research Center
on Aging, who has studied tea at length. “The
extensive history of daily, long-term intake of
tea indicates a high level of safety, although
that usage does not adequately address the
issue scientifically,” Blumberg says. “Other than
the issue of caffeine intake, I am aware of only
two documented situations where tea may have
an adverse impact on nutritional status.” These
involve the possibility that tea might affect levels
of folate and iron in the body.
In the first case, while many observational
studies and some clinical trials suggest tea
reduces the risk of cancer, a few test-tube
studies suggest a potential pro-carcinogenic
mechanism of tea catechins (naturally occurring
antioxidant compounds) by reducing folate
levels. In the only human study available to date
examining this effect, researchers tested a
green-tea extract and a black-tea extract in a
crossover randomized clinical trial. The study
measured bioavailability—the ability of the body
to use a nutrient—by giving a high dose of folic
acid to seven healthy individuals and then
measuring their blood levels of folate. Only the
green-tea extract, which contained 51 milligrams
of green-tea catechins, significantly
reduced folate levels.
In the second instance, a systematic review
addressed concerns about the potential of tea
to inhibit the absorption of iron—specifically the
“nonheme” iron found in plants as well as in
animal tissue. The 35 studies on iron absorption
and black tea that were reviewed didn’t include any clinical trials. Based on the 12 highestquality
studies, there was a measurable inhibition
of iron bioavailability, but one that presents
no threat to healthy adults with normal
iron status. “While this may present the
potential for an adverse impact in people with
iron-deficiency anemia,” Blumberg notes, “it
may also present a benefit to people (especially
older men) with a high iron intake, as
some studies suggest increased iron status is
a risk factor for cardiovascular disease.”
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I take supplements of vitamin B12 daily, plus a “mature” multivitamin containing vitaminB12. Should I be worried about the risk of overdosing on vitamin B12?
Answer : Unlike many other nutrients, the Institute of Medicine has not established a Tolerable Upper Intake Level for vitamin B12, so there’s no official point at which taking B12 becomes “too much of a good thing.” According to Jacob Selhub, PhD, director of the Vitamin Metabolism Laboratory at Tufts’ Jean Mayer USDA Human Nutrition Research Center on Aging, however, the body’s absorption of vitamin B12 is very limited, irrespective of dose. So there’s no need to worry about overdosing on B12 in supplements or in food.
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We’ve read that drinking a lot of fruit juice or eating a lot of turmeric or blueberries can help prevent Alzheimer’s. But isn’t it futile after 50 or 60 years to try this? Wouldn’t it take a lifetime of eating these foods to do any good? At what age approximately does it really not make any difference?
Answer : James Joseph, PhD, research physiologist at the Neuroscience Laboratory at Tufts’ Jean Mayer USDA Human Nutrition Research Center on Aging, answers: “We now have data from one of our collaborators which shows that aged individuals (average age in their 60s) exhibiting early memory declines who were given Concord grape or blueberry juice (approximately 12 ounces per day) showed improvements in memory on several parameters, such as list recall, intrusion errors, etc. In addition, all of our initial studies with blueberries, strawberries, blackberries or walnuts were done in old animals. So it is never too late to start.”
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Your March 2009 newsletter discusses obesity, as measured by Body Mass Index (BMI). Would you please advise how to calculate BMI?
Answer : The easiest way to calculate BMI, especially for the math-phobic, is to enter your height and weight into one of the many BMI calculators on the Web, such as the National Heart, Lung and Blood Institute’s page at www.nhlbisupport.com/bmi. If you’d rather do it youself, the standard formula requires you to convert your weight from pounds into kilograms (divide by 2.2) and height from inches into meters (divide by 39.37). To figure BMI, divide your weight in kilograms by your height in meters squared. If you’d rather skip the metric system, try this: weight in pounds x 703 / height in inches 2. Either way, for example, a person who’s 165 pounds and 5-foot-9 (69 inches) has a BMI of 24.4.
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I’ve heard that California almonds are being irradiated. Does this mean that these almonds no longer have any nutritional value? Are they harmful to eat?
Answer : A Irradiation is one of the possible methods to satisfy a 2007 USDA requirement that raw almonds be pasteurized to prevent foodborne illness, such as the salmonella outbreaks in 2001 and 2004 traced to raw almonds. According to the Almond Board of California, however, “Radiation as a pasteurization method has been considered, but not actively pursued.” And a spokesperson for the almond trade group confirms that no California almonds are being irradiated.
You may encounter other foods, however, that have been irradiated to kill foodborne bacteria. Last year, for example, in the wake of illnesses traced to contaminated leafy vegetables, the US Food and Drug Administration (FDA) approved a rule modification to permit the (optional) irradiation of fresh iceberg lettuce and fresh spinach at the maximum absorbed dose. The FDA has determined that the process is safe and effective in decreasing or eliminating harmful bacteria on a variety of foods. Irradiation of foods is allowed in nearly 40 countries and has been endorsed by the World Health Organization and the American Medical Association. Foods that have been irradiated do not lose any of their nutritional value.
Nonetheless, irradiated foods remain controversial and some consumer groups have expressed concerns about their safety. If you prefer to avoid irradiated foods, simply check the package label: All foods that have been irradiated must carry the international symbol for irradiation, the “radura” (shown here), as well as the phrase, “treated by irradiation” (or “with irradiation”). You can also opt for organic foods, since irradiation is not acceptable under the rules of the USDA National Organic Program; thus, foods labeled “organic” cannot be irradiated.
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QI’ve read that wild
blueberries are good
for you, but most of us
have access only to cultivated
berries. Does this mean
that cultivated berries are not
as good for you?
Answer : AIt’s true that USDA testing in 2004 found
that wild blueberries had more antioxidant
capacity than the same size serving
of cultivated blueberries (while also scoring
higher than cranberries, strawberries, plums
and raspberries). But the nation’s leading
researcher on the health benefits of blueberries,
James A. Joseph, PhD, a research physiologist
at Tufts’ Jean Mayer USDA Human Nutrition
Research Center on Aging, says that from a
nutritional standpoint, wild and cultivated blueberries
can be considered equal.
Tufts researchers and others are studying
blueberries’ antioxidant benefits, including the
promise that they could boost brain functions
that weaken with aging. Other research has
suggested that blueberries may help improve
cholesterol levels, protect against stroke, aid urinary-
tract health and even inhibit tumor growth.
If you really want to seek out wild blueberries,
note that they can often be found frozen.
Whether wild or cultivated, frozen blueberries
are an economical way to “go blue” even when
fresh berries are out of season; typically frozen
when the berries are at their peak, they offer
the same nutritional benefits as fresh.
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QI like fresh salmon, but
it’s too expensive so I
buy canned salmon. Is
canned salmon as
nutritious as fresh?
Answer : AComparing canned salmon (liquids
drained) with an equal quantity of cooked
fresh salmon, each offers some nutritional
advantages. The differences derive from how
canned fish is processed, and from the fact that
bones are included in canned salmon. Those edible bits of bone give canned salmon significantly
higher levels of calcium (18 times as
much) and phosphorus per serving than fresh
salmon. Canned salmon also has more vitamin
D. On the downside, canned salmon contains
more than six times as much sodium—399
milligrams per 100 grams (about 3.5 ounces)—
as fresh salmon. Both canned and fresh
salmon give you roughly the same amount of
protein, 22-23 grams per 100 grams.
Some of the fat found in fresh salmon is
lost in processing, meaning canned salmon
has only two-thirds the calories of the same
amount of the cooked fresh fish. Unfor -
tunately, some of the heart-healthy omega-3
fatty acids that salmon is prized for get lost
as well; canned salmon has only about half
the total amount of the two most important
omega-3s, EPA and DHA, found in a comparable
serving of fresh salmon.
So canned salmon can be part of a
healthy diet, though you’ll need to eat it more
frequently to get enough omega-3s.
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QI am confused by whether
shrimp and other shellfish are
good in the diet due to
attributes such as being high
in protein, low in fat and low in
calories, or bad because they are high
in cholesterol. Please clarify.
Answer : AThe good news for shrimp and other
shellfish is that the major dietary factor
that raises LDL (“bad”) cholesterol is saturated
fat, not dietary cholesterol, according to
Alice H. Lichtenstein, DSc, director of the
Cardiovascular Nutrition Laboratory at Tufts’
Jean Mayer USDA Human Nutrition Research
Center on Aging. Although a three-ounce serving
of shrimp has 166 milligrams of cholesterol—
more than half what you should consume
in a day—it has almost zero saturated fat. So
shrimp and other shellfish are a good substitute
for entrees containing meat and dairy fat, both
high in saturated fat. At just 84 calories in a
three-ounce serving of shrimp, it can also help
keep down your diet’s calorie count—as long as
you don’t batter and fry the shrimp or serve
swimming in butter!
Shrimp are also a source of protein (18
grams per serving), vitamin B12, selenium,
niacin, iron, phosphorus and zinc. Be aware,
however, that you can’t count on shrimp and
other shellfish for the health-promoting omega-
3 fatty acids found in salmon and other fatty
fish. A serving of shrimp contains only 295 milligrams
of total omega-3s—about one-sixth the
amount in a comparable serving of salmon.
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QBack in the 1950s, Carlton
Fredericks, a popular radio
personality, touted the
virtues of blackstrap molasses.
Mom bought some for Dad, but after
one taste it was history. About a year
ago, though, I ran across it in the store
and was amazed that it appears to be
a “superfood.” Why have you never
mentioned blackstrap molasses in
your newsletter?
Answer : AMolasses is a concentrated byproduct of
refining sugar cane into table sugar.
”Black strap” molasses comes from the
third and final boiling of the sugar syrup, so this strongly flavored, thick, dark molasses variety
is highest in mineral content and lowest in
sugar. Unlike sugar or artificial sweeteners,
molasses is a source of minerals your body
needs, including manganese, magnesium, iron,
copper, calcium and potassium. Amounts vary
widely by brand, so check the label if you’re buying molasses for its mineral content. And
before you start gulping blackstrap molasses
as a “superfood,” keep in mind that each
tablespoonful also has about 50 calories.
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I know that 100%
whole-wheat bread is
better for you than
white bread. But how
nutritious are breads such as
rye and pumpernickel?
Answer : Both rye bread and pumpernickel bread
are typically made with a mix of rye flour
and wheat flour. Brands vary widely as a
source of whole grains, so check the ingredients
list on the label for “whole rye flour” and
“whole wheat flour.” Besides being a whole
grain—just like whole wheat—rye is a good
choice for people watching their glycemic index
(a measure of how rapidly the body converts
food to sugars), such as diabetics. Rye has an
unusually high level of fiber in its endosperm,
the inner part that serves as a seedling’s food
supply. (When grains are processed rather than
whole, the outer bran and germ are stripped
away and the endosperm is all that remains.)
This fiber-rich endosperm generally gives rye
products—including rye bread and pumpernickel
bread—a lower glycemic index than products
made from wheat. On most other measures of
nutritional value, rye and pumpernickel bread
are not significantly different from regular
whole-wheat bread. Both are richer sources of
folate and folic acid and, depending on the
brand, may be marginally lower in saturated fat.
Whole-wheat bread is higher in protein and
magnesium while typically lower in sodium per
slice. All three types of bread contain about the
same amount of calories per serving.
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I enjoy eating buffalo
meat when I am able to
buy it from local
farmers. It’s very lean,
but is it more healthful than
regular beef in other ways?
Answer : Buffalo (bison) meat is indeed much naturally
lower in fat than beef from cattle.
Its proportion of saturated, polyunsaturated and monounsaturated fat is very similar to
that of beef, so the fact that bison has only
one-quarter to one-fifth the overall fat means
you’re getting that much less saturated fat
per serving. Since fat is a dense source of
calories, bison meat generally has only about
two-thirds the calories of the same quantity
of beef. Bison is also slightly lower per serving
in dietary cholesterol than beef and higher
in iron and vitamin B12.
Because of its lower fat content, bison
shrinks less and cooks a little faster than
beef. That can also make it tough when
cooked beyond medium or when cooked at
high temperatures; some buffalo-meat purveyors
recommend slow roasting at no more
than 275 degrees. Such low temperatures can
be a food-safety issue, so be sure to freeze
raw buffalo meat or keep it refrigerated at 40
degrees.
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Do egg yolks really differ from egg whites in terms of raising “bad” (LDL) cholesterol? What’s a safe weekly limit for both parts of the egg?
Answer : A Yolks contain the fat and cholesterol in an egg, in addition to protein, vitamins and minerals. The whites contain primarily protein, only a very little fat and no cholesterol. Eggs have gotten a bad rap as a cholesterol culprit, because they are a concentrated source of cholesterol in the diet and there’s confusion between dietary cholesterol and blood cholesterol. While dietary cholesterol can contribute to unhealthy LDL levels in some, the primary dietary cause of LDL problems is saturated fat.How many eggs can you safely eat? Egg proponents cite a 1999 study of 117,000 adults that found little impact on the risk of heart disease or stroke from consuming one egg a day. Current recommendations, however, are that individuals with healthy LDL cholesterol concentrations eat 300 milligrams of dietary cholesterol or less per day. With 210 milligrams of dietary cholesterol in the yolk of one large egg, a single egg at breakfast puts you at about two-thirds of your daily maximum. If you are limiting saturated fat in your diet, by minimizing animal fat intake (meat and dairy), staying within the limit should not be a problem. If you are more liberal with your intake of animal fats, it may be wise to be a little more careful about egg intake.
Fortunately, for people who want or need to limit their dietary cholesterol and want their daily eggs as well, there are a couple of good options: Make an omelet with 1 whole egg and two egg whites or use egg substitutes.
It is currently recommended that individuals with high LDL cholesterol concentrations should try to limit their intake to 200 milligrams of cholesterol or less per day. For some of these individuals, sometimes referred to as “cholesterol responsive,” dietary cholesterol such as that in eggs can have a big effect on their LDL cholesterol concentrations.
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I know it can be harmful to eat charred, blackened meat. Is the same true of overtoasted nuts, burnt potatoes and the like?
Answer : A We posed this question to Rashmi Sinha, PhD, senior investigator at the National Cancer Institute and a leading expert on carcinogens in charred foods. His answer might be characterized as good news, bad news: Unlike blackened meat, charred vegetables do not have one group of carcinogenic compounds, heterocyclic aromatic amines. But they probably do contain polycyclic aromatic hydrocarbon compounds that have also been linked with cancers in animals. So to be on the safe side, trim any burnt edges and discard badly charred vegetables.
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How does microwaving affect the nutritional value of food?
Answer : We posed this question to Helen Rasmussen, PhD, RD, senior research dietitian at Tufts’ Jean Mayer USDA Human Nutrition Research Center on Aging. It turns out that the effect of microwave cooking on the nutritional value of food is an intriguing question—so much so that Rasmussen put one of her students on the case, Emily Evans, a master of science candidate at Tufts’ Friedman School. Microwaving is usually faster than other cooking methods, Evans points out, and may actually have some advantages when it comes to preserving nutrients. For one thing, microwaving uses less water than boiling, and foods cooked in water lose more nutrients than those cooked without. Microwave ovens also typically use less heat than other cooking methods, making them less destructive. Water-soluble vitamins such as vitamins B, C and folic acid are very heatsensitive. Recent studies at Cornell University found that spinach cooked in the microwave kept most of its folic acid, but lost about 77% when cooked on the stove.
The bottom line, according to Evans:Microwave cooking does not cause significant loss of human health-related nutrients in foods, as long as the amount of water used and cooking time are limited.
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I take flax-oil supplements every day and I was alarmed to read in your September 2008 issue that high intake of alpha-linolenic acid (ALA), found in flax, was actually associated with an increase in risk for early age-related macular degeneration (AMD). Should I stop taking flax oil?
Answer : We checked with the lead researcher on that study, Elaine W. T. Chong, MBBS, of the University of Melbourne in Australia, who replied: “This does not mean that our results are definitive. People should not be overly concerned regarding ALA flax-seed capsule intake. However, they should be aware that it is the long-chain omega-3 fatty acids (DHA and EPA) that have been associated with a protective effect for AMD and other health conditions,and less so ALA.”
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Is buckwheat a grain or is it actually a seed? I have it for breakfast every morning, and am wondering if I’m getting all the benefits one gets from grains.
Answer : According to the Whole Grains Council www.wholegrainscouncil.org, buckwheat is neither a grain nor, despite its name, a relative of wheat; botanically, it’s a cousin of rhubarb. But nutritionally, buckwheat qualifies as a “whole grain,” so your morning routine is fine. The part of the buckwheat plant that we eat, ground into flour or hulled for groats (called “kasha” in the US), is indeed the seed. A half-cup of dry buckwheat groats contains 8.4 grams of dietary fiber—more than twice a comparable serving of oatmeal. Buckwheat is also the only “whole grain” known to have high levels of an antioxidant called rutin that improves blood circulation and may keep LDL cholesterol from blocking blood vessels. People with celiac disease or gluten allergies can safely consume buckwheat, because it contains no gluten.
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How can I keep from overeating during the holidays?
Answer : Helen Rasmussen, PhD, RD, an instructor at Tufts’ Friedman School, enlisted Laura Ficker, a master’s candidate at the school, to offer these holiday tips:
• Don’t go to holiday parties and dinners hungry. It’s easy to eat faster and greater amounts when you’re hungry. Eat a wholesome breakfast and lunch to avoid overeating later in the day.
• Be conscious of the food around you. Fill your plate one time, half with vegetables, one quarter with a lean meat and the rest with starches of your choice. Eat slowly and stop when you are full.
• Make a conscious choice to limit high-fat items. High-fat ingredients can be found in fried, creamy and cheese-filled dishes associated with the holidays. If you can’t control the ingredients that go in to a dish, simply limit yourself to a smaller helping size.
• Drink plenty of water. Alcohol and coffee in excess can dehydrate your body. Additionally, eggnog and other holiday drinks can easily add 350-400 calories per drink. Choose calorie-free water to help fill up your stomach and keep you hydrated.
• If you’re the cook, decrease the fat in your gravy. Use a fat separator or refrigerate the pan juices and skim the fat off before making the gravy. This can save up to 55 grams of fat per cup (495 calories) and help you avoid having greasy gravy.
• Avoid leftovers. Give them away or choose not to take any home. Not having heaps of leftovers looming makes it easier to get back into a normal and healthful food routine when the holidays are over.
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Your newsletter often states the advantages of omega-3 fatty acids. But how much fish should I consume to benefit?
Answer : Both the American Heart Association and the 2005 federal Dietary Guidelines for Americans recommend consuming at least two servings of fish per week for heart health. The dietary guidelines, whose fish recommendation specifically targets people who have already experienced a cardiac event, go on to spell out that two servings should total approximately eight ounces. Not just any fish will do for omega-3s, however: “It’s best to go with ‘dark’-fleshed fish, such as salmon, trout or tuna,” advises Alice H. Lichtenstein, DSc, director of the Cardiovascular Nutrition Laboratory at Tufts’ Jean Mayer USDA Human Nutrition Research Center on Aging. “Fried fish fillets don’t count, due to the low omega-3 levels in the type of fish usually used, added calories that come from the cooking process and the potential for trans fats from the type of fat used to fry the fish in.”
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With the increasing evidence for the benefits of vitamin D, is there any artificial light that will give me the benefits of sunshine in making vitamin D?
Answer : While not even the most avid vitamin D advocate suggests broiling yourself in a tanning booth, it is true that people in northern climes can’t get enough sunshine during winter to trigger the body’s natural ability to make vitamin D. The easiest alternative is to take vitamin D supplements. But if you prefer to bring the sun indoors, you’ll need a special kind of “medium-pressure” lamp that puts out the UVB rays the body uses in making vitamin D.Many so-called “sunlamps” (such as those designed to combat Seasonal Affective Disorder) and tanning salons use only “high-pressure” lamps that produce UVA light but not UVB—increasing your risk for skin cancer without producing vitamin D. The US Food and Drug Administration has sanctioned some sunlamps made by Sperti (, 859-331-0800), such as the KDB D/UV lamp, as a vitamin-D producer for people who have trouble absorbing vitamin D from food, such as those with gastric bypass surgery, Crohn’s disease or cystic fibrosis.
There is no official recommendation for UVB exposure, from the sun or sunlamps, although a review article last year in the New England Journal of Medicineconcluded, “Exposure of arms and legs for 5 to 30 minutes (depending on time of day, season, latitude and skin pigmentation) between the hours of 10 a.m. and 3 p.m. twice a week is often adequate.” The nonprofit Vitamin D Council says 15 to 20 minutes of noonday sun exposure (or when “the sun is high enough in the sky so that your shadow is shorter than you are”), twice a week, will give most fair-skinned people in most of the continental US enough of the vitamin. If using a sunlamp, 10 to 15 minutes twice a week is probably plenty, and you should apply sunscreen to protect your face, since facial skin makes very little vitamin D.
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My doctor has prescribed me Coumadin (warfarin) to fight blood clots. I see that you’re supposed to avoid foods that contain “large amounts” of vitamin K when taking warfarin. Can you offer any more specific guidance as to what “large amounts” means?
Answer : We checked with Sarah L. Booth, PhD, director of the Vitamin K Laboratory at Tufts’ Jean Mayer USDA Human Nutrition Research Center on Aging, who shared the advice on warfarin and vitamin K she’d recently reviewed for the Tufts-New England Medical Center: Vitamin K helps blood to clot, so it can change the way warfarin works. This does not mean you need to stop eating foods high in vitamin K, such as leafy green vegetables, which are also high in other heart-healthy nutrients. Your goal is to keep your diet consistent by eating the same amount of vitamin K foods from week to week. This will help warfarin to work its best. If you are not able to eat for a few days, or you are going to make big changes to your diet, call your doctor.
The rule of thumb is the greener the plant, the more vitamin K. You should aim to eat a similar mix of foods very high, high and medium in vitamin K daily. Foods very high in vitamin K (serving size 1/2 cup) include spinach, escarole, kale, seaweed, endive and collard greens. Turnip greens and Swiss chard are high in vitamin K. Medium foods include broccoli, Brussels sprouts, Romaine lettuce (1 cup), parsley (10 sprigs), green cabbage, spring onions, cole slaw, pistachios and mustard greens. Other vegetables and all fruits are low sources of vitamin K. Multivitamins and liquid nutrition supplements such as Ensure and Boost also contain vitamin K, so keep your use of these the same from week to week.
Also keep in mind that cranberry and grapefruit juice can increase warfarin in your blood; limit to four ounces per day. Vitamin E, fish oil supplements and alcohol in high amounts can change the way warfarin works. Herbal supplements should not be taken with warfarin. If in doubt, talk to your doctor.
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Dr. Dean Ornish claims that olive oil
reduces blood flow by 31%. Is this true
and if so is it a reason to stop using
olive oil?
Answer : Ernst J. Schaefer, MD, director of the HNRCA Lipid Metabolism Laboratory at Tufts, explains that the
problem with olive oil—despite all of the hype about its benefits—is that it is low in essential fatty acids (either
omega-6 or omega-3). Olive oil contains about 85% monounsaturated fatty acids, mainly oleic acid, and about
15% saturated fatty acids, mainly palmitic acid. In contrast,
soybean oil has only about 8% saturated fat, and has a lot more essential fatty acids—both omega-6 (mainly linoleic acid) and omega-3 (mainly alpha-linolenic acid, ALA). Canola oil also has quite a bit of ALA—an omega-3
fatty acid—and much more omega-6 than olive oil, though somewhat less than soybean oil. Fish oil, of course, contains at least 50% eicosapentaenoic acid (EPA) and docosahexaenoic
acid (DHA)—the omega-3 fatty acids that are good for the brain and the heart in terms of preventing arrhythmias and dementia.
When Dr. Ornish cites a study that olive oil reduces blood
flow by 31%, he is talking about brachial artery (the main
artery of the upper arm) reactivity and not coronary blood
flow. It is true, however, that monounsaturated oils such as
olive oil may not be the best choice to protect against the
accumulation of fatty deposits in the inner linings of the
arteries. Tufts’ Dr. Schaefer notes that Laurence Rudel, PhD,
of Wake Forest University has done careful monkey studies
indicating that polyunsaturated fatty acids are more beneficial
than saturated fat or monounsaturated fat in preventing
diet-induced atherosclerosis. Therefore, while olive oil need
not be avoided, other vegetable oils such as canola, soybean
and other oils high in polyunsaturated fat are better options
for essential fatty acid consumption.
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Is frozen yogurt as
nutritious as regular
yogurt? What happens
to live cultures such as
acidophilus when yogurt is
frozen?
Answer : Simin Nikbin Meydani, DVM, PhD, professor
of nutrition at the Friedman School
and associate director of Tufts’ Jean
Mayer USDA Human Nutrition Research Center
on Aging, responds:
“The nutritive value of yogurt or frozen
yogurt is based on the ingredients in the yogurt,
so it will be slightly different for frozen yogurt
made by different companies. The labels should
provide the nutritional information. [Since frozen
yogurt is a dessert, it’s typically sweetened;
make sure to also check the label to see how
much added sugar you’re getting.]
“Yogurts and frozen yogurts can contain live
active cultures. Manufacturers might add extra
‘healthy’ bacteria (such as L. acidopihilus,
Bifidobacteriumor and others) for their health
effects, but not all yogurts have these extra
probiotic bacteria. Although the flash-freezing
technique used in the production of frozen
yogurt, unlike slow freezing in a freezer, should
not kill the live cultures, there is no guarantee
that this won’t occur.
“As a result, the number of bacteria in frozen
yogurt is usually lower than that in the yogurt it
was made from. Different yogurts and frozen
yogurts are made with different types of live cultures
and probiotics, however, and the levels that
remain in frozen yogurt depend on the numbers
that were in the yogurt and on the heartiness of
the specific bacteria that was used.
“The National Yogurt Association sponsors a
voluntary labeling program for frozen yogurt;
look for the ‘Live and Active Cultures’ seal on
containers of frozen yogurt. If the yogurt
doesn’t have the label, contact the manufacturer
and ask what types of bacteria their product
contains and at what level.
“Some frozen yogurts may be better sources
of probiotics than some regular yogurts. The
National Yogurt Association standard for a live
active culture frozen yogurt is 10 million cultures
per gram at time of manufacture; for
yogurt it is 100 million.”
|
What can you tell me
about the possible
toxic effect of peanut oil
lectin (PNA)? I’ve
read where the “Paleo Diet”
cites research showing that
PNA from peanuts and
peanut oil clogs the arteries.
Answer : We tracked down one of the original
researchers in those 1998 studies, David Klurfeld, PhD, who is now a national program leader in human nutrition with the USDA’s Agricultural Research Service. He replies:
“A little background is in order to understand
why we did those studies many years
ago. Rabbits and monkeys fed peanut oil had
more cardiovascular lesions than expected
from a polyunsaturated oil—almost as much
as from the most saturated fats. I developed
a method that extracted lectin from vegetable
oils and we found lectin in all refined oils at
extremely low levels. Peanut lectin is a protein
that binds to a carbohydrate on endothelial
cells, which line blood vessels. And this
lectin differs from lectins found in other seed
oils. So it was plausible that lectin explained
some or all of the unexpected effects on
lesion formation.
“Since then, epidemiological and, more
important, intervention studies with peanuts
and many types of tree nuts have shown not
only no increase in serum cholesterol or risk
of heart disease but a reduced risk. So there
is, in my opinion, no harm from consumption
of peanuts or peanut oil. This story has
developed a life of its own and has been perpetuated
on the Internet along with similar
fables.”
|
When nutritionists talk
about walnuts, do they
mean black or English
walnuts?
Answer : According to the California Walnut Board,
a trade association, the walnuts you buy
in stores—and those most commonly
touted for nutritional benefits—are “English walnuts.”
The “black walnut” is a native American
species that’s primarily used as a rootstock for
English walnuts. If you have black walnuts
growing in your yard, you’ll find the meats are
tasty, but a lot of work to crack and remove
from the shell. Nutritionally speaking, black walnuts
contain 10% less total fat and 20% less
omega-3 fatty acids than English walnuts. One
ounce of black walnuts—about 14 halves—has
175 calories, 16.7 grams of total fat and 0.57
grams of omega-3s. One ounce of English walnuts
has 185 calories, 18.5 grams of total fat
and 2.6 grams of omega-3s. Note that the highly
promoted omega-3s in walnuts are in the
form of alpha linolenic acid (ALA), which the
body must convert to the healthful omega-3s
found naturally in fish—an inefficient process.
|
We live in southern
Arizona where citrus
trees thrive and own
two well-producing
grapefruit trees. Are there prescription
drugs that do not act
well with grapefruit?
Answer : According to the Center for Food-Drug
Interaction Research and Education, led
by Tufts and the University of Florida,
most prescription drugs do not show a clinically
relevant interaction with grapefruit juice—despite
popular belief. In the late 1980s, scientists discovered
that grapefruit juice contains natural
substances that can affect the way certain prescription
medications are broken down (metabolized)
by an enzyme, known as CYP3A4. If a
person drinks grapefruit juice and takes one of
these drugs orally, more of the drug may enter
the bloodstream than would have under normal circumstances. This means that grapefruit
juice has the potential to enhance the absorption
of these drugs. The extent of a potential
interaction will vary from drug to drug, and
even from person to person. For a guide to
degree of interaction with medications by
brand name, see the center’s Web site at
grove.ufl.edu/~ned/fdic/consu.php?interaction_category=9. Patients should
consult with their pharmacist or doctor if they
have any questions about their prescription
medication(s). For patients taking medications
known to interact with grapefruit juice, there
generally are non-interacting, alternative medications
that offer safe treatment with no need
to discontinue drinking grapefruit juice. All
studies reviewed by the center support that it
is safe to consume grapefruit juice while taking
over-the-counter medication.
|
My eczema has
become worse over
the last few years. Are
there any foods that I
should avoid?
Answer : Eczema is a chronic skin disorder due
to a hypersensitivity reaction—similar to an allergy—in the skin. The role of diet is difficult to pinpoint and may vary by individual, much as with food allergies; most research on food and eczema has focused on children rather than adults. According to the
National Institutes of Health (NIH), possible dietary restrictions for eczema sufferers may include eggs, fish, peanuts and soy.
|
How does tapioca rate nutritionally?
Does it fall under
the refined food category? I
like to use it to make tapioca
pudding with Splenda and nonfat
Lactaid milk and eat about one cup
of the pudding as a dessert twice a
day. Should I cut back?
Answer : People have been eating tapioca at least
since the heyday of the Mayans, who first
figured out how to process the root of the
cassava plant (also called manioc or yuca) to
eliminate its naturally occurring cyanide.
Technically, yes, tapioca is a refined food in the
sense that the packaged tapioca you buy is
made from reconstituted, processed root; being
a root starch, rather than a grain, however,
there’s no such thing as “whole” tapioca.
Nutritionally, tapioca is pretty much as neutral
as it tastes: The dry mix used to make one cup
of tapioca pudding (not counting milk or any
sweetener) contains 170 calories, 43 grams of
carbohydrates, 219 milligrams of sodium, and
only tiny amounts of protein, fiber, vitamins and
minerals. So, if tapioca pudding satisfies your
craving for dessert, you’re probably not doing
yourself any harm, but you’re not gaining much
nutritionally, either. By comparison, while not
ordinarily considered “dessert,” a bowl of oatmeal
offers much the same consistency plus a
whole-grain nutritional bonanza: One packet of
instant oatmeal also has 170 calories, but adds
4 grams of protein, 3 grams of fiber, and a
healthful mix of minerals and vitamins. So you
might try opting for oatmeal at least once a day
instead of tapioca.
|
I read a report recently indicating
that all nuts contain
monosaturated fat. I thought
this was true only of
almonds, and that the rest contain
polyunsaturated fat. Am I wrong?
Answer : All popular nuts contain both types of fat—
and the good news is that both mono- and
polyunsaturated fat are “heart-healthy”
compared to saturated and trans fats. According
to the American Heart Asso ciation,
“Monounsaturated fats and polyunsaturated fats
appear to not raise LDL cholesterol; some studies
suggest they might even help lower LDL cholesterol slightly when eaten as part of a
low-saturated and trans-fat diet.” Each type of
nut does differ in its proportion of mono- and
polyunsaturated fats, with macadamias actually
the highest in monounsaturated fat. Walnuts
are also high in a special kind of polyunsaturated
fatty acid, alpha linoleic acid (ALA),
which the body can convert to the omega-3
fatty acids eicosapentaenoic acid (EPA) and
docosahexaenoic acid (DHA), known for a
wealth of health benefits; this is not a very
efficient conversion, however, so your best
source of omega-3s is still fatty fish like
salmon, not nuts. The chart
above shows how the fat content
(in grams) of one ounce of
whole nuts compares by type of
nut or legume.
Keep in mind that nuts are
only one way to incorporate
monounsaturated fats and
polyunsaturated fats into your diet. Other ways
include using vegetable oils such as soybean
and canola in salad dressings and while cooking.
Remember that even “heart-healthy fats”
contain calories, so although they may be
good for you, that’s only when they replace
something less-healthy in your diet. Also watch
out for added salt in the nuts you’re munching--
and be aware of the total amount you
consume.
| Monounsaturated Polyunsaturated |
ALA |
| Almonds |
8.8 g |
3.4 g |
less than 0.1 g |
| Cashews |
6.7 g |
2.2 g |
less than 0.1 g |
| Macadamias |
16.7 g |
0.4 g |
less than 0.1 g |
| Peanuts |
6.9 g |
4.4 g |
less than 0.1 g |
| Pecans |
11.6 g |
6.1 g |
0.3 g |
| Pistachios |
6.6 g |
3.8 g |
less than 0.1 g |
| Walnuts |
2.5 g |
3.4 g |
2.6 g |
|
Is much of the omega-3
lost when the skin of
the salmon is discarded?
Answer : According to Alice H. Lichtenstein,
DSc, director of the Cardiovascular
Nutrition Laboratory at Tufts’ Jean
Mayer USDA Human Nutrition Research
Center on Aging, much of salmon’s healthy
omega-3 fatty acids lie just under the skin.
Comparing total omega-3s for the same
variety of salmon in different preparations
using the USDA’s Nutrient Database, salmon
without the skin contains only 39% to 64%
of the omega-3s in the same portion of
salmon with the skin. But there’s a downside
to leaving the skin on salmon, Lich -
tenstein cautions: That same fatty layer next
to the skin may also contain some fat-soluble
contaminants, if present. If you’d rather
not eat the skin, you can make up for any
omega-3s that get lost to the trash by buying
varieties of fish that are higher in omega-3s
to begin with, including ocean-farmed
Atlantic salmon and Chinook salmon, plus
mackerel, which has 21% more of the two
most important omega-3s (EPA and DHA)
than even the most omega-3-rich salmon.
|
I have been told that
the sugar substitute
Splenda is unhealthy
due to the chemicals
used to process sugar into
Splenda. Can you clarify?
Answer : It’s true that Splenda is made using
chlorine, which sounds scary; the
sugar industry warns that you’re
“actually eating chlorine” when consuming
sucralose, the chemical sold as Splenda.
Plain sugar is transformed into sucralose by
substituting three chlorine atoms for hydrogen,
creating a substance that is not digested
by the body—so it’s effectively caloriefree—
and that’s 600 times sweeter than sugar. (Packaged Splenda also contains
dextrose and maltodextrin as bulking
agents.) But there’s no evidence that the
chlorine atoms in sucralose are any more
dangerous than they are in, say, sodium
chloride—ordinary salt. Before giving
sucralose the OK, the US Food and Drug
Administration reviewed more than 110
human and animal studies demonstrating
its safety.
|
I am enclosing an article
from a local newspaper
warning people
to avoid eating any fish
ever (“Thinking Twice About
Tuna” by Bruce Friedrich of
the People for the Ethical
Treatment of Animals, Palo
Alto Daily News). I would like
to know whether this very
alarmist article has any basis
in fact.
Answer : The article in question warns about the
dangers of mercury and other contamination
in tuna and other fish, concluding
that “Fish is anything but ‘health food.’“ While
it’s wise to be wary of potential toxins in fish,
the consensus of scientists who have examined
the evidence—as opposed to taking an ethical
stand, as PETA does, that “animals are not to
eat”—is that fish is in fact one of the healthiest
foods you can include in your diet. As reported
in the January 2007 Healthletter, a 14-member
Institute of Medicine (IOM) expert panel concluded
that the rewards of eating fish outweigh
the risks. “Confusion may have scared people
out of eating something that is beneficial for
them and maybe for their offspring,” according
to Jose M. Ordovas, PhD, director of the
Nutrition and Genomics Laboratory at Tufts’
Jean Mayer USDA Human Nutrition Center on
Aging and a member of the panel. “People
should not be scared about eating seafood.”
Almost simultaneously, an analysis of more
than 200 previous studies strongly endorsed the
cardiovascular benefits of fish consumption. The
report, published in the Journal of the American
Medical Association, concluded that the risks of
mercury and other toxins in fish are “outweighed
by potential benefits of fish intake and
should have little impact on choices of fish consumption.”
Harvard’s Dariush Mozaffarian, MD,
DrPH, co-author of the report, maintains,
“Seafood is likely the single most important
food one can consume for good health.”
No wonder, then, that the American Heart
Association and the latest federal dietary
guidelines both recommend eating fish twice
a week.
According to the IOM findings, only
women who are or who may become pregnant
or who are breast-feeding, along with
children up to age 12, need to limit seafood
consumption because of contamination risks.
This group can still consume up to 12 ounces
of fish a week, while avoiding large predatory
fish such as shark, swordfish, tilefish or king
mackerel. Others worried about contaminants
should select a variety of seafood to minimize
risk from any single source.
If you want to skip eating seafood for
ethical reasons, that’s your choice. But there’s
no scientific reason to eschew fish on the
basis of health—indeed, just the opposite is
true.
|
You mention “Body
Mass Index” (BMI),
but instead of explaining
how to calculate it
you refer to a Web site. How
can I calculate BMI without a
computer?
Answer : You can calculate BMI without resorting
to one of the many online calculators
(such as www.nhlbisupport.com/
bmi), but you may want to at least have
your own calculator handy. According to the
Centers for Disease Control and Prevention,
the official formula for calculating BMI using
common US measurements is: Divide your
weight in pounds by your height in inches
squared; then multiply the result by a conversion
factor of 703—that is, (weight/height2) x
703. So, for example, a 150-pound person who
is 5-feet-5 (65 inches) would have a BMI of
24.96: 150 divided by 4,225 (65 times 65)
equals 0.0355; times 703 equals 24.96. If
you’ve mastered the metric system, the formula
is a bit simpler: weight in kilograms
divided by height in meters squared. In either
case, you must multiply the height figure
times itself first.
|
In your May “Ask
Tufts Experts,” you
compared the nutrition
in white potatoes, sweet
potatoes and yams. But I’m
confused about the difference
between sweet potatoes and
yams?
Answer : You’re not alone! According to the North
Carolina Sweet Potato Commission, the
confusion stems from the introduction of
orange-fleshed sweet potatoes into the southern
US. Producers wanted to differentiate
them from the pale-fleshed sweet potatoes
already familiar to consumers. So they adopted
an English form of “nyami,” the African
word for the starchy, edible root of the
Dioscorea genus of plants. Despite that confus ing name, however, both the tan variety with
creamy yellow insides and the more commonly
eaten, more recently introduced
“yam”—with copper skin and deep orange
flesh—are botanically sweet potatoes. Both
are from the genus Ipomoea, the morningglory
family, and are native to the Americas
(as is the white potato—though botanically
also a different genus, again despite the
name). True African Dioscorea “yams” are
rarely sold in US markets; they are also
called Chinese yams or Chinese potatoes
(more confusion!). The US Department of
Agriculture requires that the label “yam” always be accompanied by the term “sweet
potato,” as in “yam sweet potato.”
To clarify our original answer, in terms of
vitamin A, the orange-fleshed variety of sweet
potatoes (sold as “yams”) are higher in beta
carotene than the paler-fleshed type. (Thanks
to reader and dietician Barbara Ashburn for
her research assist on “yams.”)
|
Your Special Report on
aspartame and high-fructose
corn syrup (September
Healthletter) made me
wonder about ordinary table
sugar. How does it compare to
fructose in terms of calories? And
if I want to cut calories but am
still concerned about aspartame,
what are my options?
Answer : In fact, regular table sugar (sucrose) isn’t so
different from high-fructose corn syrup
(HFCS), which contains either 55% or 42%
fructose plus other sugars, primarily glucose. Table
sugar is 50% fructose and 50% glucose. Both table
sugar and HFCS contain four calories per gram, so
if you’re counting calories you should limit both
sweeteners.
To satisfy your sweet tooth without calories or
aspartame, the FDA has approved four other artificial
sweeteners:
Saccharin: Some 200 to 700 times sweeter
than sugar, saccharin was removed from the
agency’s Generally Recognized As Safe (GRAS) list
in 1972; the FDA proposed a ban in 1977. Concerns
over bladder cancer in rats given high doses of saccharin
were alleviated, however, by subsequent
National Cancer Institute findings. Those showed that
the bladder tumors were caused by a mechanism
that doesn’t apply to humans, and that saccharin
does not cause cancer in people. The National
Toxicology Program determined in 2000 that saccharin
should no longer be listed as a carcinogen.
Saccharin is sold under brand names including
Sweet’N Low, Sweet Twin and Necta Sweet.
Acesulfame-K: Some 200 times sweeter than sugar, with zero calories, acesulfame-k is sold
under brands including Sunett and Sweet One.
More than 90 studies have supported its safety.
Neotame: A whopping 7,000 to 13,000 times
sweeter than sugar, neotame has zero calories.
It’s been approved as a general-purpose sweetener
in a variety of foods, and more than 100 studies
have shown it to be safe.
Sucralose: Also the subject of controversy,
sucralose, sold as Splenda, is 600 times sweeter
than sugar. It adds no calories because it isn’t
digested in the body. Sucralose is made by substituting
three chlorine atoms for hydrogen in
ordinary sugar, a technology that the sugar industry
has used to raise concerns about sucralose.
The FDA reviewed more than 110 human and animal
studies demonstrating the safety of sucralose,
however. And there’s nothing necessarily scary
about ingesting chlorine atoms; half the atoms in
ordinary table salt, after all, are chlorine.
|
In your June 2007
newsletter you reported
the recommended
AREDS antioxidants
combination to reduce the risk
of macular degeneration. It
included copper. Recently, on a
TV program, I heard a doctor
warning against using copper
as part of a multivitamin
intake, stating that copper was
bad for your health. It would
be reassuring reading your
opinion on this. If copper is to
be used, in what amounts?
Answer : Copper is an essential mineral with an
established Recommended Dietary
Allowance (RDA) of 900 micrograms (0.9
milligrams) per day for adults and a Tolerable
Upper Intake Level (UL) of 10,000 micrograms
(10 milligrams) daily. (The UL is the maximum
daily intake of a nutrient that is likely to pose
no risks of adverse health affects for almost all
individuals.) According to Jeffrey Blumberg,
PhD, director of the Antioxidants Research
Laboratory at Tufts’ Jean Mayer USDA Human
Nutrition Research Center on Aging, high levels
of zinc may interfere with the absorption of
copper. Since a high dose of zinc—80 milligrams,
compared to the RDA of 9 milligrams
daily for women and 11 for men—was used in
the AREDS supplement, copper was added to
the formula. In this case, the copper is not
aimed at eye health but rather to offset the
potential for impaired copper bioavailability
caused by the high levels of zinc.
That’s not to say, however, that copper
doesn’t have important health benefits.
According to the USDA’s Agricultural Research
Service (ARS), “Copper often is overlooked as
an important nutrient when considering diets
that promote cardiovascular health in humans.”
One indication of the relationship between copper
and heart health comes from the finding
that copper concentrations in diseased hearts often are lower than the concentrations found
in healthy hearts.
Another comes from recent research at
the ARS’ Grand Forks Human Nutrition
Research Center, showing that dietary copper
may be beneficial even when the heart
already is diseased. In the experiments, mice
consuming a high-copper diet reversed a surgically
induced enlargement of the heart and
showed greatly reduced structural damage to
the heart. More research will be needed to
see if these findings can be extended to
humans, however.
Adding copper-rich foods to the diet may
be particularly important for women, according
to ARS experts. Dietary surveys indicate
that 10-25% of women have copper intakes
lower than the RDA.
Foods that are high in copper content
include shrimp, lobster, crab, whole grains, nuts, seeds, beans, lentils and mushrooms. It’s
practically impossible to get an unsafe
amount of copper from food alone; for example,
a three-ounce serving of shrimp contains
just 163 micrograms of copper. Even dietary
supplements don’t approach the UL for copper:
A typical multivitamin or “vision formula”
supplement might contain 2,000 micrograms
(2 milligrams) of copper, just one-fifth the
limit of safety.
|
I enjoy Indian food
very much and it
appears very healthy,
with many vegetables
that are tasty and interesting.
But most Indian recipes are
made with clarified butter or
“ghee.” I imagine this is not
very beneficial from the point
of view of fat and atherosclerosis,
but I may be wrong. Could
you explain and give your
opinion?
Answer : Ghee—“clarified” butter, with the
milk solids removed—is made by
heating unsalted butter to separate
the milk solids from the pure butterfat.
Although practitioners of Ayurvedic medicine
in India claim that ghee has special health properties, some experts argue
that the prevalence of ghee in Indian
cuisine is actually a contributor to the
high rates of heart disease in that
country. In any case, Alice H.
Lichtenstein, DSc, director of the
Cardiovascular Nutrition Laboratory at
Tufts’ Jean Mayer Human Nutrition
Research Center on Aging (HNRCA),
says that since ghee is butterfat, it’s
high in saturated fat. “Substitute liquid
vegetable oil,” she advises. “It may not
taste quite the same, but given all the
other seasonings it is a small price to pay for lowering your saturated fat
intake. And, as always, go heavy on the
vegetables when you are putting the dish
together.”
|
I keep reading that
adding milk to tea
interferes with its
antioxidant activity.
How about soy milk?
Answer : Jeffrey Blumberg, PhD, director of
Tufts’ HNRCA Antioxidants Research
Laboratory, replies, “I am unaware
of any studies that have examined the
effect of soy milk on the antioxidant activity
of tea. However, the basic premise of
this interaction is that the protein (mostly
casein) in milk binds to the tea flavonoids,
particularly the catechins, and thus
inhibits their antioxidant capacity as well
as bioavailability. As soy milk also contains
substantial protein (albeit not casein), a
similar reaction is plausible.” He cautions,
though, that the evidence that cow milk
does bind significantly to tea flavonoids
and impairs their antioxidant activity and
bioavailability is equivocal.
|
Is there any relationship
between
blood type and
nutrition? Are
certain foods detrimental
to some blood types and
excellent for other blood
types?
Answer : The notion that the four major
blood types evolved in different
environments and thus predispose
people to different nutritional needs was
popularized by naturopath Peter D’Adamo
in a 1996 bestselling book, Eat Right 4 Your
Type. According to D’Adamo, people with
type-O blood, for instance, evolved as
hunters and should eat plenty of red
meat, while agrarian type-As should eat
more grains. D’Adamo claimed to have
collected “over 1,000 scientific articles
on blood types and their correlations to
disease, biochemistry, nutrition and
anthropology.”
But a search of two leading nutrition
journals, the Journal of Nutrition and the
American Journal of Clinical Nutrition, going
back more than 40 years finds only 14
citations even mentioning the words
“blood type,” none of which have anything
to do with matching diet to blood
type. A search of the National Library of
Medicine’s PubMed database for “blood
type” and “diet” turns up only seven
citations, two of which are articles
debunking D’Adamo’s theory and none
that support this notion. In short, the scientific
evidence for this idea is slim to
nonexistent.
“The truth is that there is no scientific
evidence to support that dietary fad,”
says José M. Ordovas, PhD, director of
the Nutrition and Genomics Laboratory at Tufts’ Jean Mayer USDA Human
Nutrition Research Center on Aging.
“Moreover, I have not seen any serious
attempt within the mainstream science
to carry out any study to investigate
this concept.”
Blood type actually has little to do
with body chemistry or digestion. And
even the classification of four blood
types is only part of the story: Since
pathologist Karl Landsteiner identified
the A, AB, B and O groups early in the
1920s, some 200 different blood group
substances have been identified and
grouped within 19 different systems.
Most experts discount the idea that
your blood type should dictate any
departure from the basics of a healthy
diet. “Telling people that they should eat
more meat because they have type-O
blood is irresponsible,” argued cardiologist
and diet-book author Dean Ornish,
MD, when Eat Right 4 Your Type was first
published. The late Victor Herbert, MD,
a physician at Mount Sinai Medical
Center and frequent critic of alternative
medicine, said the idea of linking blood
type and diet is “pure horse manure. It
has no relation to reality. The genes for
blood type have nothing to do with the
genes that handle the food we eat.”
Scientists such as those at Tufts’
Nutrition and Genomics Laboratory are
investigating ways your genetic inheritance
might influence your nutritional
needs, metabolism, aging and propensity
to obesity. But this research looks at
genetic factors much more complex
than simple blood-type grouping.
|
In your August newsletter
it is stated that we
should not fry fish. My
wife says you are talking
about battered fish or shrimp that
is deep-fried, such as fish sticks or
fast-food fish sandwiches. She says
it’s OK to “fry” fish such as plain
Tilapia in a tablespoon of olive oil
in a skillet on the stove top. I say
that your article means neither
deep frying nor skillet frying
should be done. Who’s right?
Answer : You owe your wife a nice fish dinner
(baked, not deep-fried). The research
we cited refers specifically to commercially
fried fish, mostly breaded and
fried in hydrogenated fat, of the sort your
wife has in mind. Alice H. Lichtenstein,
DSC, director of the Cardiovascular Nutrition
Laboratory at the Jean Mayer USDA Human
Nutrition Center on Aging at Tufts, says, “If
someone wants to fry at home that is fine,
just as long as they use liquid vegetable oil
and don’t need to be concerned about the
extra calories. I frequently sauté onions in
pan and then ‘fry’ salmon. I am not certain
other people would call that frying but it
looks like what your wife is thinking of. The
advantage of my technique is you don’t
heat the oven up and you have only one
pan to clean up.”
|
In your July newsletter,
you indicated that whole
grain consists of bran,
germ and endosperm.
For years I have been purchasing
wheat germ and wheat bran and
using a heaping tablespoon of
each in a liquid mixture at breakfast
and dinner. From your article
I gather that I am failing to consume
a whole grain product. Is the
endosperm essential? Do I need to
change this consumption pattern?
Answer : Each part of a whole kernel of wheat
brings something to the nutritional
party. According to the Wheat Foods
Council and the Consultative
Group on International Agricultural Research, the bran (outer layer)
contains the largest amount of fiber, though
otherwise it has little nutritional value. The
germ (inner part—essentially the embryo of
the berry) is a rich source of trace minerals,
unsaturated fats, B vitamins, antioxidants
and phytochemicals. The germ has a nutty
flavor and is oily, which causes it to turn
rancid quickly. The endosperm (middle
layer) contains mostly protein and carbohydrates
along with small amounts of B vitamins,
niacin and iron. The endosperm actually
makes up the majority of the kernel,
and is the primary source of many wheat
flours.
When scientists have studied the health
benefits of whole grains, much of their data
has come from looking at people’s dietary
patterns. Researchers have not looked separately
at the health benefits of the individual
components of wheat, so we don’t know whether consuming these components separately
will have the same effect as eating
whole grains.
Moreover, people who seek out wholegrain
products are likely eating in other
“heart-healthy” ways that reduce their risk of
cardiovascular disease, notes Tufts expert
Alice H. Lichtenstein. “Even though
researchers try to correct for those factors,
my feeling is it is the whole package, not just
one component,” she adds.
|
Everyone is singing the
praises of fish oil
nowadays, but I read
that it raises your LDL
bad) cholesterol? Is that true?
so, what is the alternative?
Answer : Alice H. Lichtenstein, DSc, director of the
Cardiovascular Nutrition Laboratory at
Tufts’ Jean Mayer Human Nutrition
Research Center on Aging, explains that fish is
beneficial because it’s an excellent source of
the omega-3 fatty acids EPA and DHA. (For
more on the benefits of omega-3s—and why
other dietary sources such as walnuts and flaxseeds aren’t an efficient way to get
EPA/DHA—see the July Special Report.) Fish
and fish oil raise LDL cholesterol only in
some hypertriglyceridemic individuals—those
with an unhealthy excess of triglycerides in
the blood—who take two to four grams a day
of fish oil. (That’s a lot of fish oil, by the
way: A typical fish-oil supplement contains
300-500 milligrams of EPA/DHA, and manufacturers
recommend one to three such capsules
daily, for a total of no more than about
one gram. A three-ounce serving of salmon,
before cooking, contains a little less than a
gram of total omega-3s.) Even in such
cases, Lichtenstein explains, the person’s
decrease in triglycerides and increase in
“good” HDL cholesterol offset any potential adverse effects from the small increase in
LDL. For most people, anyway, this is not an
issue, so go ahead and eat fish! The
American Heart Association and the latest
federal dietary guidelines both recommend
eating fish—especially the fatty, cold-water
varieties like salmon highest in omega-3s—at
least twice a week.
|
What is the recommend
daily dose of folate? Is
there an upper limit?
Answer : According to the Institute of Medicine,
which sets Dietary Reference Intakes
(DRI), the recommended daily amount of
folate for adult males is 400 micrograms. The
recommendation is the same for adult
females, except for during pregnancy, when
it increases to 600 micrograms daily, and
lactation, 500 micrograms. For comparison, a
half-cup serving of spinach, a food relatively
high in folate, has 29 micrograms. Much of
our dietary folate comes from foods that
have been supplemented with this nutrient—
so, for example, a one-third-cup serving of
Kellogg’s All Bran Buds contains 403 micrograms
of folate, 101% of the recommended
daily value.
The Tolerable Upper Intake Level (UL)—
the maximum amount of a daily nutrient
that’s likely to cause no adverse effects—for
folate is 1,000 micrograms daily for adult men
or women. In the case of folate, the UL
applies to synthetic forms obtained from supplements,
fortified foods, or a combination of
the two.
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At our local supermarkets
a fish called “steelhead
trout” is sold. The
flesh is pinkish like
salmon, not like trout. What
exactly is this fish and is it a
good source of omega-3?
Answer : Steelhead trout (Oncorhynchus mykiss) is a
rainbow trout that has spent part of its
life in the sea. Also called “salmon trout”
or “sea-run trout,” it’s a large, bluish fish
that’s prized by sport fishermen. According to
the Alaska Department of Fish and Game,
“There are no major physical differences
between rainbow and steelhead trout; however,
the nature of their differing lifestyles has resulted in subtle differences in color, shape
and general appearance.” All trout and
salmon, along with chars, belong to the
family Salmonidae, sometimes referred to as
“salmonids.” Steelhead trout are actually
similar to some Pacific salmon in their ecological
needs and life cycles: Both are born
in freshwater streams, then swim to the
ocean after one to three years; like salmon,
steelhead return to their native streams to
spawn, but they don’t necessarily die after
spawning, as salmon do.
Wild steelhead trout, like wild salmon, get
the pinkish-orange color of their flesh from
crustaceans and other colorful prey they consume.
Farm-raised salmonids are naturally
gray-fleshed; producers dye the flesh to make
it look more appealing to consumers. Most steelhead trout available in supermarkets is
farm-raised.
A 100-gram serving (about 3.5 ounces)
of farm-raised steelhead, cooked by dry
heat, provides 1.236 grams of omega-3 fatty
acids. A similar portion of farm-raised
Atlantic salmon contains 2.26 grams of
omega-3s. Steelhead trout is high in protein
(24.2 grams in 100 grams) and relatively
low in calories (170), and is also a good
source of niacin, vitamin B12, pantothenic
acid and selenium.
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In your April issue on
“Eating for Endurance,”
you state that
plant proteins are
incomplete proteins with the
exception of soy protein. I
thought quinoa supplied all the
essential amino acids. Isn’t
quinoa a complete protein
grain?
Answer : Actually, neither soy nor quinoa—which is
technically a seed, but is cooked like a
grain—is a “complete protein” in the
sense of delivering as much of all essential
amino acids as do animal options such as beef,
milk or eggs. Quinoa and soy, as well as wheat,
are very good protein sources and deliver at
least some percentage of all the amino acids
your body needs. But plant proteins, including
these three, fall short of beef in their share of
certain amino acids. Coupled with beans or
another complementary protein source, however,
quinoa delivers a complete package of protein.
Quinoa also contains more iron than most
grains, and provides some calcium, phosphorus,
folate and B vitamins. No wonder the Incas
called quinoa “the mother grain”!
|
Is there a chart of daily
food allowances for
people over 80 years
old?
Answer : We’ve received a number of questions
along this line, wondering about dietary
data specifically for older adults. If you
have access to the Internet and the free Adobe
Acrobat Reader software (available at
www.adobe.com/products/acrobat/readstep2.
html), you can view a complete chart of
Dietary Reference Intakes (DRI) established by
the Institute of Medicine at www.iom.edu/
File.aspx?ID=21372. This chart breaks out
daily dietary needs by gender and age, including
categories for males and females ages 70-
plus. You can also go to the Web site for the new federal dietary pyramid at , enter your age, gender and
typical exercise level, and receive a customized
version of the pyramid, including a
complete eating plan.
You’re correct in thinking that dietary
needs change with age. Although the recommended
intakes for many vitamins and
nutrients are the same for all adults, the
adult DRIs increase with age for vitamins
including C, D, K and B6 as well as calcium.
Your need for some minerals actually
decreases with age—notably iron (for males
after 18 and females after 50), chromium, phosphorus (after age 18), sodium and
chloride. But don’t worry too much about
the numbers—in general, if you eat a balanced,
varied diet like that spelled out by
MyPyramid, you’ll get most of the nutrients
you need, whatever your age.
|
Does regular exercising
enlarge one’s
lipid particles (HDL,
LDL and VLDL),
which is supposed to be beneficial
to one’s health?
Answer : “The major determinant of VLDL, LDL
and HDL particle size is the level of
triglyceride in the blood,” replies Ernst
J. Schaefer, MD, chief of the Lipid
Metabolism Laboratory at Tufts’ Jean Mayer
USDA Human Nutrition Research Center on
Aging. “Regular exercise and weight loss if
indicated can help lower triglyceride to less
than 150 mg/dl. Below this level, most of
LDL particles are type or large particles.”
|
I have seen many
emails and Web postings
about people
getting sick from the
artificial sweetener aspartame.
I am a diet cola consumer,
so I wonder: Is aspartame
dangerous?
Answer : The Internet is full of misinformation
about aspartame, according to David
Hattan, PhD, of the Food and Drug
Administration’s (FDA) division of health
effects evaluation. Hattan says there is no
“credible evidence,” to support, for example,
rumored links between aspartame and systemic
lupus or multiple sclerosis. True,
ingesting aspartame results in the production
of substances that could be toxic at
high doses: methanol, formaldehyde and
formate. But the amounts are small—less
methanol, for instance, than found in tomatoes
or citrus juices.
The FDA does require products containing
aspartame to be labeled for phenylalanine,
an amino acid that can cause problems
for people with a rare hereditary condition.
Another amino acid in aspartame
that’s the subject of Internet rumors, aspartic
acid, could cause brain damage at
extremely high doses. But the FDA calculates that most aspartame users
consume only 4 to 7 percent of the safe
maximum daily intake.
Other claims against aspartame, such as
supposed links to seizures and birth defects,
have failed to be supported by testing, even
when lab animals ingested aspartame at
doses far higher than humans would ever
consume. The FDA says aspartame, sold
under trade names such as NutraSweet and
Equal, is one of the most thoroughly tested
and studied food additives the agency has
ever approved. More than 100 toxicological
and clinical studies confirm that aspartame is
safe for the general population.
|
I’ve read that calcium
should be taken/ingested
periodically during
the day, as only a certain
amount is absorbed at
once. Please tell me if this is
important and, if so, how
much is advisable to take and
at what intervals?
Answer : Bess Dawson-Hughes, MD, professor of
medicine at Tufts and chief of the Bone
Metabolism Laboratory at the Jean
Mayer USDA Human Nutrition Research
Center on Aging, responds: “Calcium is better
absorbed if taken in doses of 500 milligrams
or less. So 1,000 milligrams as a supplement
should be taken in doses of 500 milligrams
twice daily.”
|
Is canned spinach just
as good as fresh
spinach to protect my
vision?
Answer : Scientists believe that eating lutein, a nutrient found in green vegetables such
as spinach, kale and broccoli, may help
prevent eyesight deterioration. It is believed
that lutein protects against cataracts and agerelated
macular degeneration (AMD), both of
which cause loss of vision. According to Allen
Taylor, PhD, director of the Laboratory for
Nutrition and Vision Research at Tufts’ Jean
Mayer USDA Human Nutrition Research
Center on Aging, the lutein content of spinach
is not damaged in the canning process. So,
yes, canned spinach will be as beneficial for
vision as fresh spinach.
Although leafy greens—spinach, kale,
chard, turnip and mustard greens, collards,
chicory, cress, radicchio, parsley and even
dandelion greens—are by far the best sources
of lutein, you can also add lutein to your diet by eating peas, summer squash, leeks and
pasta made with spinach.
|
We always have a
bounty of fresh
fruit—more than we
can eat before it goes
bad. Is it possible to freeze
fresh fruit without adding
sugar?
Answer : Healthletter recipe consultant Patsy
Jamieson replies: “To freeze fresh
fruit without sugar, peel and pit, if
necessary, or rinse and pat dry. Slice or cut
fruit into bite-sized pieces. Spread on a tray,
cover and freeze until solid. Transfer to a
plastic food storage bag, remove air from bag, seal and label. Freeze for up to eight
months. To prevent peaches, bananas and
mangos from turning brown, coat with
lemon juice or an anti-browning product,
such as Fruit-Fresh or Ever-Fresh.”
|
What’s the safe level of daily
vitamin D? Is it different for
older people? Also, I take
fish-oil pills each day as recommended
by my heart specialist, as
well as a vitamin D supplement, and
I’m worried that I may be getting too
much vitamin D. How much vitamin
D is found in fish-oil pills if any?
Answer : The recommended intake of vitamin D—but
not the safe limit—does increase with age:
The Institute of Medicine has set the daily
adequate intake for adults ages 19 to 50 at 200
IU of vitamin D, for ages 51 to 70 at 400 IU, and
for those older than age 70 at 600 IU. Many
experts, however, argue that those levels should
be raised, and research has shown that 800 to
1,000 IU daily may be needed to obtain the full
range of health benefits.
It is possible to get too much of a good
thing, though: Vitamin D can be toxic at high levels
of intake. Too much vitamin D can cause dangerous calcium deposits in organs, including
the heart, and can damage the kidneys. The
Institute of Medicine’s “Tolerable Upper Intake
Level” (UL) for vitamin D is set at 2,000 IU
daily for adults, regardless of age, although the
lowest dose at which adverse effects have
been registered is 3,800 IU. Given the modest
amounts even in foods richest in vitamin D—98
IU in a cup of fortified milk, for example, and
360 IU in 3.5 ounces of cooked salmon—it’s
highly unlikely you could ever eat your way to
an overdose. Typical vitamin D supplements
contain 400 to 800 IU in a single capsule,
however, so take them judiciously.
The issue of vitamin D in fish oil actually
more concerns cod liver oil, which mothers
used to give their children to combat rickets
(caused by a deficiency of vitamin D). A tablespoon
of cod liver oil contains 1,360 IU, so it’s
true that combining cod liver oil and vitamin D
capsules could quickly exceed safe limits.
Checking with two leading supplement manufacturers,
however, confirms that fish-oil capsules
contain levels of vitamin D too low to
detect.
|
I have been hearing about
cinnamon as a “cure” or at
least a treatment for diabetes.
As a patient with medically
controlled type 2 diabetes, I am naturally
interested. Anything to it?
Answer : A 2003 study of 60 people with type 2 diabetes
did find that intake of one to six
grams of cinnamon daily improved blood
glucose levels, as well as lipid factors (such as
cholesterol) important to cardiovascular disease.
Subsequent research on possible benefits for diabetics
from the popular spice, however, have
been disappointing. Most recently, two reviews of
the scientific literature both came to similar negative
conclusions: “Based on the currently available
evidence, cinnamon should not be recommended
for the improvement of glycemic control,”
wrote a team of Dutch researchers in
December 2007. And University of Connecticut
experts in January 2008 concluded that cinnamon
does not appear to improve a key measure
of chronic blood-glucose levels, fasting blood glucose
or lipids in patients with type 1 or type 2
diabetes. So, at least for now, it looks as though
cinnamon belongs on the spice rack, not in the
medicine cabinet.
|
I have been told that
using olive oil for
cooking causes the oil
to hydrogenate and is
therefore unhealthy. Would
you please address this?
Answer : “Hydrogenation” means just what it
sounds like—adding hydrogen to the
molecules of a vegetable oil. The
process uses hydrogen gas plus a metal catalyst,
such as nickel. So unless you have a
highly unusual kitchen, it’s not something that
happens in the home. Merely cooking with
olive oil or any other oil cannot hydrogenate it.
The concern about hydrogenated oils
springs from research into trans fat, which
has been found to increase LDL-cholesterol
(the “bad” kind) without increasing “good”
HDL-cholesterol levels. Tufts researchers have
also found that trans fats tend to decrease
the particle size of LDL-cholesterol—making
them even more unhealthy by depositing
more cholesterol in the arteries. While some
trans fats occur naturally in animal products,
by far the biggest dietary source is vegetable
oil that has been hydrogenated. This chemical
process turns liquid vegetable oils into solids
at room temperature, such as stick margarine
and shortening. These hydrogenated oils have
been widely used in processed foods and
baked goods and frying fast food. Many manufacturers
are now phasing out hydrogenated
oils, and the FDA will require trans fats to be
identified on food labels as of next year.
|
Do you know anything
about a substance
called “714X” that has
been used in the treatment
of cancer? My cousin told
me she heard something about
it on TV. Where can I find out
more about it and its use?
Answer : Also called “trimethylbicyclonitramineoheptane
chloride,” 714X is named for
the initials of its inventor, Gaston Naessens (G and N being the 7th and 14th
letters of the alphabet), plus X, the 24th letter
of the alphabet, for 1924, the year
Naessens was born. That unorthodox
nomenclature should give you a clue about
the scientific standing of 714X. Naessens,
who is French but has long worked in
Quebec, claims his compound can cure not
only cancer but also multiple sclerosis,
fibromyalgia and other diseases. As long ago
as 1967, however, the American Cancer
Society investigated and found no evidence
for those claims or for Naessens’ supposed
scientific credentials. According to
Quackwatch, which monitors dubious medical
claims, no clinical trial and no reputable
scientific journal has ever found that 714X
is effective against any health condition,
including cancer. In 1990, the Canadian
Health Protection Branch concluded, “No
scientific evidence has been provided to
support any claims made for the drug” and
“deplored” the use of 714X to treat cancer
and AIDS. In the US, the Food and Drug
Administration has successfully prosecuted
those importing 714X.
As tempting as it may be to try such supposed
“wonder drugs” against diseases as
frightening as cancer, you risk becoming a
victim of fraud as well. For the most up-todate
patient information on cancer treatment
and a set of interactive treatment-decision
tools, see the American Cancer Society’s Web
site at www.cancer.org.
|
I understand that Concord grapes are
high in nutritional value. Because I
don’t see this variety in local super
markets, do other red grapes have
similar nutritional value?
Answer : In general, according to James A. Joseph, PhD, chief of the
Neuroscience Laboratory at Tufts’ Jean Mayer USDA Human
Nutrition Research Center on Aging, grapes with the most color
have the highest degree of antioxidants. Anthocyanins, the pigments
that give red and purple grapes their color, have been associated with
a variety of possible health benefits; they are not unique to Concord
grapes. Some white grapes, however, are rich in proanthocyanidins,
another type of antioxidant found in grape seeds and skin that may
have health benefits.
|
Which is “fresher”—
vegetables canned soon
after harvesting, frozen
or so-called “fresh” as
pawed over by the public or in
plastic?
Answer : There’s no real scientific measure of
“freshness,” but if you mean vegetables
that are closest in nutrient content
to freshly picked vegetables, the best
bet is probably frozen produce. Alice H.
Lichtenstein, DSc, Stanley N. Gershoff professor
of nutrition science and policy at
Tufts’ Friedman School, says, “For the most
part, frozen vegetables are processed close
to the point of harvesting, and, unless
thawed and refrozen prior to sale, should
retain most of their nutrients. Fresh vegetables
—more so than frozen or canned—
can vary in quality, depending on when
they were picked relative to when they are
available for purchase and the conditions
under which they were stored, the length
of time stored and the conditions under
which they are displayed.
Canned vegetables are different. They
are cooked and hence, not comparable to
frozen or fresh vegetables. Canned vegetables
are lower in heat-labile nutrients—
those that are unstable when heated, as in
the canning process.” Many canned vegetables
also have added salt; if you do opt
for canned, make sure to look for those
that are low in sodium. Of course, it is also
important how the vegetables are stored
and prepared once you get them home
from the market: Minimize excessive heat
and cooking fluid unless it is going to be
consumed, such as in soups.
|
As a vegetarian, I am
interested in the combination
of fruits and vegetables that will provide a
complete set of essential
amino acids in sufficient
quantities. Can you help?
Answer : Jeanne P. Goldberg, PhD, director of
the Center on Nutrition Communication
and the Nutrition Communication
Program at Tufts’ Friedman School, answers,
“This is really not difficult. In general, vegetables
and grains are better sources of protein
than fruits. Single groups of plant foods
typically do not contain all of the essential
amino acids in the balance that the body
needs them, but if you eat a variety you will
get all you need. For example, legumes are
low in methionine, a sulfur-containing amino acid, but grains have quite a bit. On the
other hand, grains are limited in lysine,
which the legumes do have. By eating rice
and beans together, the amino acid pattern
of each is complemented. That approach,
eating different vegetable foods together,
serves to insure that people on vegetarian
diets get all of the essential amino acids
they need.”
|
Is it safe to eat the
mold that forms on
cheese? I tend to throw
it out, but wonder if
there are cheeses that have
desirable molds.
Answer : AIt’s important to differentiate between
molds used to make certain cheeses and
molds that form later in your refrigerator.
Blue-veined cheeses such as Roquefort, blue,
Gorgonzola and Stilton are created by introducing
mold spores, while cheeses such as
Brie and Camembert have white surface
molds. The molds used to manufacture these
cheeses are safe to eat, according to the
USDA Food Safety and Inspection Service
(FSIS). But when such cheeses develop molds
not part of the manufacturing process, they
should be discarded (soft cheeses) or the
mold and at least an inch around it should be
cut away (hard cheeses). Other hard cheeses
can be similarly trimmed and then used. All
soft cheeses such as cottage cheese, cream
cheese, Neufchatel and chevre, as well as
crumbled, sliced and shredded cheeses, should
be discarded if they develop mold.
Why throw away even the “good part” of
such cheeses? The FSIS warns, “Foods with
high moisture content can be contaminated
below the surface. Shredded, sliced or crumbled
cheese can be contaminated by the cutting
instrument. Moldy soft cheese can also
have bacteria growing along with the mold.”
Hard cheeses can be rescued, on the other
hand, because mold generally cannot penetrate
deep into such products.
|
What’s the difference
between whole-wheat
pastry flour and regular
whole-wheat flour?
Answer : Whole-wheat pastry flour is milled from a
soft variety of wheat, which has less
gluten-forming potential than regular whole-wheat flour, and is therefore an excellent
choice for tender baked goods. White
whole-wheat flour is a special variety of hard
wheat. Although it has a lighter color and
sweeter flavor than regular whole-wheat
flour, this flour contains all the benefits of
whole-grain flour because it is milled from
the entire wheat berry. Both types of flour
are available in natural foods sections of
supermarkets or through Web sources, such
as kingarthurflour.com or
bobsredmill.com. Store all whole-wheat flours in an airtight container or bag on the
refrigerator or freezer. For an example of
using either type of flour, see our
Wholesome Gingerbread Cookies recipe
below.
|
I usually agree with
most of your articles,
but I think you
dropped the ball on
your “51 Healthy Foods”
(August) concerning peanut
butter. You did not specify the
peanut butter should be “natural.”
Most others have hydrogenated
trans fat and you
know that is harmful.
Answer : According to the US Department of
Agriculture’s Agricultural Research
Service (ARS), “Recurring rumors that
commercial peanut butters contain trans
fats… have no basis in fact.” True, small
amounts of hydrogenated vegetable oils are
added to commercial peanut butters—1%-2%
of total weight—to keep the peanut oil from
separating out. And the hydrogenation
process can lead to the formation of trans
fatty acids, which increase the risk of cardiovascular
disease. But ARS testing of 11
brands of peanut butter, including major
store brands and “natural” varieties, found
no detectable trans fats in any of the samples.
It’s expected that under new FDA labeling
guidelines, all peanut butter will declare
zero trans fat on the label. The tested peanut
butters did have oleic acid, from 19%-27%
by weight, a monosaturated fat believed to
have beneficial cardiovascular effects.
|
In your list of “51
Healthy Foods,” you
list carrots but do not
say cooked or raw. It
is my impression that the
human system cannot digest
raw carrots because the cellulose
walls are resistant. Is this
correct?
Answer : While you can get nutrients and fiber
from raw carrots, it’s true that one important
nutrient—beta-carotene, which the
body turns into vitamin A—is tightly bound to the
protein in plants. A 2003 study at the Hebrew
University of Jerusalem, published
in the European Journal of Nutrition, concluded, “Significantly more beta-carotene was
absorbed from meals containing cooked, pureed
carrots than from meals containing the raw vegetable.”
Research at the University of Arkansas
found similar results; levels of beta-carotene and
other antioxidants were even higher when the carrots
weren’t peeled before pureeing and cooking.
|
For the lactose intolerant,
does soy milk
offer as much calcium
benefit as cow’s milk?
Answer : Soy milk is not a good natural source of
calcium, but many brands of soy milk are
fortified with calcium. Fortified soy milk typically has 200-400 milligrams of calcium per
cup, which would provide 20%-40% of your RDA
of calcium. For a chart comparing the calcium in
various brands, see www.soyfoods.com/nutrition/
CalciumChart.html.
|
I make smoothies
using only fresh squeezed
OJ, yogurt
and fresh or frozen
fruit (mostly bananas and
berries). Is the fiber in the
fruit lost by blending them
into the smoothie? What
about other vitamins and
minerals?
Answer : Not to worry, says Alice H.
Lichtenstein, DSc, Gershoff Professor
of Nutrition Science and Policy at
Tufts’ Friedman School. You’re losing some
fiber from the orange by squeezing out the
juice and discarding the rest. Otherwise,
however, all the fiber should remain, even
after combining into a smoothie, and the
fruits’ vitamins and minerals should be
intact. Heating can destroy some nutrients,
but not blending. (We trust, by the way, that
you’re using low- or non-fat yogurt in that
smoothie?)
|
Is there a difference
in the effect on the
body between natural
(l-alpha tocopherol)
and synthetic (d,ltocopherol)
vitamin E?
Answer : Vitamin E (as alpha-tocopherol) can
exist in two configurations, like a right
and left hand (the d and l forms,
respectively), explains Jeffrey B. Blumberg,
PhD, chief of the Antioxidants Research
Laboratory and Senior Scientist at Tufts’
Jean Mayer USDA Human Nutrition
Research Center on Aging. Dietary vitamin E
is always found as the l form while synthetic
vitamin E is generally an equal mixture of
the d and l forms. A vitamin E binding protein
in the liver transfers the l form into
lipoproteins for transport throughout the
body and discriminates against the d form
such that it is rapidly excreted. Thus, milligram
for milligram, the natural dietary l
form is about twice as potent as the d form that’s mixed into synthetic vitamin E. This
difference is partly compensated for, however,
by the way International Units (IU) are
used to measure vitamin E: One IU of vitamin
E contains 1.0 milligram of the d,l mixture,
but it takes just 0.74 mg of the l form
to equal 1 IU.
|
Can you compare the nutritional
value of sweet potatoes/
yams with white Idaho
baking potatoes? What
about fiber content? Sweet potatoes
seem to contain more fibrous material,
but such impressions can be
misleading.
Answer : Sweet potatoes, yams (technically a
different vegetable) and white potatoes
all have their nutritional pluses, but
you’re correct in thinking that sweet potatoes
outdo their white-fleshed cousins in terms of
dietary fiber. Exact numbers vary depending
on variety, but generally a cup of diced,
peeled sweet potato contains 4 grams of
fiber—nearly double the 1.8 grams in the
same amount of peeled white potato (3
grams if you eat the peel). Yams provide the
most fiber of all, with 6.2 grams per cup of
peeled, diced yams.
Calorie and protein counts are comparable.
As you might guess by their orange color,
sweet potatoes contain a whopping amount
of vitamin A—almost 19,000 IU per cup, or
nearly four times the Daily Value. Yams have
only a fraction as much vitamin A—about 200
IU—and regular potatoes, none at all. White
potatoes and yams do contain more vitamin C
than sweet potatoes, though. Yams provide
the most calcium, potassium and folate.
Correction: Several sharp-eyed readers wondered
about our reference to “milligrams” of
vitamin D in an article on page 8 of the
February 2006 Healthletter. Vitamin D, of
course, is measured in International Units (IU),
which is what the article should have said.
|
I understand how to
identify trans fats as
“partially hydrogenated.”
But I
sometimes see “fully hydrogenated”
—for example, on
Reduced Fat Jif Peanut
Butter. Can you please
explain what “fully hydrogenated”
means and what, if
any, impact it has on our
health?
Answer : To understand the difference
between “partially” and “fully hydrogenated”
oils, you’ll need a short
chemistry lesson—bear with us! In saturated
fats, all the positions for hydrogen on
the carbon atoms are filled. Monounsaturated
fats have one pair of carbon
atoms per chain that are connected to
each other instead of to hydrogen atoms
this carbon-carbon bond is thus “unsaturated”);
so oleic acid, a monounsaturated
fatty acid, which has 18 carbon atoms per
chain, is denoted as 18:1. Polyunsaturated
fats have more than one such carbon-carbon
bond; linoleic acid, for example, is
18:2, meaning it has two “unsaturated”
bonds in a chain of 18.
When oils get “hydrogenated,” all of
these unsaturated bonds are catalytically
converted to saturated bonds. In “partially
hydrogenated” fat, some of the unsaturated
bonds remain, but their geometry is
changed to a “trans” configuration that
lets the molecules lie parallel to each
other. These more densely packed “trans
fats” are thus solid at room temperature
and handy for restaurant and bakery use.
Still with us? OK. When oils are “fully
hydrogenated,” all their bonds get
changed to hydrogen-carbon and there are no more “trans” molecules. Since most
vegetable oil is primarily 18:2 (polyunsaturated),
you end up with stearic acid
(18:0), a saturated fatty acid. The good
news is that, in the body, stearic acid
does not have the same effect, for the
most part, as other, less-healthy saturated
fatty acids because it can get metabolized
to oleic acid (18:1)—a healthier
monounsaturated fat. Alice H.
Lichtenstein, DSc, director of the
Cardiovascular Nutrition Laboratory at
Tufts’ Jean Mayer USDA Human Nutrition Research Center on Aging, concludes,
“Hence, fully hydrogenating is
one apparently good approach to avoiding
trans fats while changing the physical
form of the oil.”
|
The new federal
dietary guidelines
call for at least two
servings of fish a
week. At this time of year,
the only fish available in my
grocery store is farm-raised.
I have also read that you
should limit your consumption
of farm-raised fish to
two times a month. What
should I do?
Answer : The new dietary guidelines don’t
actually set a recommended serving
amount for fish, but do note,
“Evidence suggests that consuming
approximately two servings of fish per
week (approximately eight ounces total)
may reduce the risk of mortality from
coronary heart disease and that consuming
EPA (eicosapentaenoic acid) and DHA
(docosahexaenoic acid) may reduce the
risk of mortality from cardiovascular disease
in people who have already experienced
a cardiac event.” EPA and DHA are
omega-3 fatty acids found in fish and
shellfish. The American Heart Association
does specifically recommend consuming
fish twice a week.
The FDA has not issued any recommended
limits on consumption of farmraised
fish, though there are certain FDA
recommended limits, specifically for pregnant
women and children, to avoid mercury
in fish. Concern about farm-raised salmon
arose after a study by the Environmental
Working Group found polychlorinated
biphenyls (PCBs), which the Environmental
Protection Agency (EPA) calls “a probable
human carcinogen,” in 70 percent of such
fish they bought at supermarkets.
But that study tested only 10 salmon fillets.
Mark Woodin, PhD, a Tufts epidemiologist,
has noted that while farm-raised
salmon probably does have higher levels of
PCBs than wild salmon, it’s very difficult to say just how toxic they might be. The EPA’s
limits on PCBs are stricter than the FDA’s,
but are based on the amount of PCBs
thought to be capable of causing one additional
cancer case in 100,000 people over a
70-year lifetime.
You have to balance risks and benefits,
advises Alice Lichtenstein, Gershoff Professor
at Tufts’ Friedman School of Nutrition Science
and Policy. “The risk of developing cardiovascular
disease (CVD) is high; it is the leading
cause of death and disability in the US, and
half of women in the US will die of CVD.
Other than the special issue of pregnant
women and children, the risk of adverse
effects from contaminants in fish is extremely
low, theoretical at this point.”
If you’re still wary, try canned tuna and
salmon, which usually use wild fish because
it’s firmer. All year-round, many supermarkets
offer high-quality frozen fish that may include
wild varieties.
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I recently read that
one shouldn’t
microwave food in
plastic containers
because carcinogens are
released into the food. Does
this apply to all plastic containers,
even those specifically
designed for microwaving?
Answer : The supposed risks of carcinogens
leaching from plastic into food when
microwaved have reached the status
of urban legend. The US Food and Drug
Administration (FDA) has tried to reassure
the public, noting that “the FDA carefully
reviews the substances used to make plastics
designed for food use.” Yes, says FDA
consumer-safety official Edward Machuga,
PhD, substances used to make plastics can
leach into food. “But as part of the approval
process, the FDA considers the amount of a
substance expected to migrate into food and
the toxicological concerns about the particular
chemical.” As long as you use plastics as
intended—don’t microwave re | |