Getting Your Vitamins
recommend a boost in antioxidants, but they say it's not necessary
to spend megabucks on megadoses of vitamins.
away the pills and keep eating those fruits and veggies. You've
heard this before from nutritionists who for years have said that
a balanced diet ought to be enough to keep us health). Now, after
an exhaustive review of research, the nation's top scientists
have come to the same conclusion.
you eat a healthy diet there is rarely a need for antioxidant
supplements, according to a report by the institute of Medicine,
a part of the National Academies of Sciences. Researchers found
no evidence that large doses of anti-oxidants--vitamins C and
E, selenium, and beta-carotene--prevent chronic diseases.
the group did revise the Recommended Dietary, Allowances (RDAs)
for antioxidants and, for the first time, set an upper intake
level--the largest amount that a person can take without risking
glad they set a limit. A lot of people assume a little is good,
but more is better. That isn't always the case," says Chris
Rosenbloom, Ph.D., spokesperson for the American Dietetic Association
and acting chair of the nutrition department at Georgia State
report seems to contradict earlier information about antioxidants.
There is evidence that free radicals (compounds that cause damage
to cells) are linked to a risk of cancer and heart disease, but
there is no proof that antioxidants in humans attack free radicals
or limit their damage. It's only been proven in laboratories.
Therefore, no evidence exists that taking megadoses of antioxidants
prevents cancer, heart disease, or Alzheimer's disease.
public is very confused because often when these studies get reported
all the facts aren't in," says Sandra Schlicker, director
of the study at the Institute of Medicine.
revising the RDAs, the panel looked at published studies and focused
on trials involving humans--not animals. The take-home message
of this report is simple: Eat more fruits and vegetables every,
day. While the panel did not say how many to eat, it did endorse
the five-a-day eating plan, advising people to eat at least five
servings of fruits and vegetables a day. A typical serving is
1/2 cup of berries, cut-up fruit, or cooked vegetables. One 6-ounce
glass of orange juice also is considered a serving. The report,
Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium,
and Carotenoids, is available online at http://books.nap.edu/catalog/9810.html.
are some of the new recommendations.
RDA: Women, 8 milligrams (12 IU). Men, 10 milligrams (15 IU).
RDA: 15 milligrams (22 IU) of natural vitamin E, also called d-alpha-tocopherol,
for men and women.
intake limit: 1,000 milligrams. Anything higher increases your
risk of uncontrolled bleeding.
E has been associated with reducing heart disease because it blocks
oxidation of LDL (bad) cholesterol, making the cholesterol less
likely to cling to artery walls. However, only one out of four
large-scale trials of megadoses of vitamin E showed a reduced
risk of heart attacks.
literature is very conflicting," says Maret Traber, Ph.D.,
associate professor at the Linus Pauling Institute at Oregon State
University, and Institute of Medicine panelist. "There is
a lot of experimental data on human tissue and in test tubes,
but the studies done on humans are not conclusive enough to prove
a beneficial effect."
vitamin E is found in fat, some people may need to meet the RDA
by taking a supplement. "If you're eating 3,000 calories
a day, it's easy to get your 15 milligrams, so don't worry about
it," Traber says. "If you're eating only 1,500 calories
a day, you may have trouble getting there. I'd rather see someone
take a vitamin E supplement and eat a low-fat, low-calorie diet
rich in fruit and vegetables than for the person to eat more fat
just to get the vitamin E," Traber says.
buying the supplement, look for natural vitamin E, also known
as d-alpha-tocopherol. Researchers used to think synthetic vitamin
E, known as dl-alpha-tocopherol, was just as effective, but it
is not, Traber says. Many multivitamins contain synthetic vitamin
E, Traber warns, so check labels carefully.
food sources: Vegetable oils, such as sunflower and safflower;
nuts; and seeds. Smaller amounts of vitamin E are found in dairy
foods, eggs, beef, whole grains, fruits, and vegetables.
RDA: 60 milligrams.
RDA: Women, 75 milligrams. Men, 90 milligrams. People who smoke
should increase the RDA of vitamin C by 35 milligrams.
intake limit: 2,000 milligrams for men and women. Taking more
than the recommended upper limit may cause gastrointestinal distress.
studies found an association between vitamin C and a reduced risk
for cancer and heart disease, but few established a true cause-and-effect
A. Jacob, Ph.D., a member of the institute's panel and research
chemist with the USDA Western Human Nutrition Research Center
in Davis, California, says most of the studies on megadoses of
vitamin C had mixed results or were neutral, including those that
linked vitamin C to staving off the common cold or preventing
heart disease and cancer.
didn't show harmful outcomes. But if they didn't show consistently
positive results, you can't use that as a basis for an RDA,"
of the research on vitamin C has never shown direct cause and
effect. Studies have found only an "association" with
health benefits. For example, research may show that people with
a high vitamin C intake have lower blood pressure. However, there
is no scientific proof that the vitamin is responsible because
many other components of a healthy diet may lower blood pressure.
"There is an association there, but it doesn't prove that
vitamin C lowers blood pressure," Jacob says.
easy to get enough vitamin C in your diet. One 6-ounce glass of
orange juice has enough vitamin C--about 78 milligrams--to meet
the RDA for women. Vitamin C-rich fruits and vegetables typically
average about 40 milligrams per serving, Jacob says.
food sources: Citrus fruits and juices, kiwifruit, broccoli, strawberries,
and red or green sweet peppers.
RDA: Women, 55 micrograms. Men, 70 micrograms.
RDA: 55 micrograms for men and women.
intake limit: 400 micrograms. Higher amounts can cause brittleness
in hair and nails.
suggesting a link between selenium intake and reduced risk of
prostate, colon, and lung cancer aren't conclusive enough to warrant
adding a supplement. In fact, if you live in the United States,
chances are you're getting enough selenium in your diet. The reason:
selenium is in the soil. Produce grown in selenium-rich soil will
contain the mineral, says Dr. Raymond Burk, director of clinical
nutrition research unit at Vanderbilt University.
says the old RDA that distinguished between men and women was
based on body weight, but new research shows that's not necessary.
An upper limit of 400 micrograms was set because too much selenium
causes hair to fall out, and problems with fingernails and toenails.
Best food sources: Brazil nuts, seafood, meat, chicken, and whole-grain
and other carotenoids (lutein, zeaxanthin, and lycopene)
RDA: None. There never was one.
intake limit: Beta-carotene supplements are not advised other
than as a source of vitamin A.
appears to be a link between carotenoids and a decreased risk
of age-related macular degeneration, cataracts, and some cancers.
However, no clinical trial has shown that carotenoids--compounds
found in red and yellow plants--are responsible for lowering risk.
is encouraging research with certain carotenoids in the prevention
of some diseases, but not enough to say what the requirement should
be," says Susan Taylor Mayne, Ph.D., associate professor
of epidemiology and public health at Yale University School of
Medicine. There are some promising associations, such as with
lutein and macular degeneration, but they are preliminary, she
all the articles written about lycopene's effect on prostate cancer
don't mean much?
all interesting data, but at this point, it is far from proven,"
Mayne says. "And most of the studies have been done on food,
not pills." Mayne recommends getting your carotenoids by
eating a variety of foods.
food sources: Sweet potatoes, carrots, tomatoes, peppers, spinach,
kale, collard greens, squash, apricots, mangoes, cantaloupe, and