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Affiliated
Physicians Monthly
February 2009 | |
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Straight Talk About Vitamins and Supplements:
They've Been Disappointing, but Gradually
We're Getting it Right.
The
idea behind taking a dietary supplement is a powerful one. The
science of nutrition has grown explosively, and now so many substances
are known to be important for your health that even with a good
balanced diet it seems impossible to get everything you need without
supplements. More than 50% of Americans take a vitamin supplement every day, supporting a $23 billion industry.
But the actual benefits of taking vitamins and supplements have been difficult to pin down. Are
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they
real? Do they exist? Taking a daily multivitamin prevents
the development of vitamin-deficiency diseases. This is true, but
it is not terribly satisfying. Other than that, the evidence
supporting the use of vitamins for health has been thin.
Are fruits and vegetables good for you? Yes! The higher your level of consumption of fruits and vegetables-the actual foods-the lower your risk of cardiovascular disease.
But
taking comparable quantities of purified "active ingredients" as
supplements has consistently been found to be lacking in
benefits.
Antioxidant therapy was found to be "inversely correlated"
with prevention of ischemic heart disease. That means
taking antioxidant supplements made it more likely you would develop
heart disease, not less.
Beta carotene supplementation was all the rage until the 1990s, when it was found that it led to higher rates of lung cancer than in people who took a placebo.
A high fiber diet does not protect against colon cancer. Screening colonoscopy does.
A recent large study following 15,000 men over 10 years showed that Vitamin C and Vitamin E supplements had no effect in reducing the risk of cancer or heart disease. Disappointing.
Lycopene
is ineffective against prostate enlargement symptoms, and its
antioxidant effect only occurs in conjunction with other tomato
components. The health claims for lycopene have been removed from
the labels of Heinz ketchup.
Glucosamine chondroitin is a constituent component of new cartilage, but it is the same as placebo for treatment of arthritis. Saw palmetto is the same as placebo for treatment of symptoms of prostate enlargement. It seemed like such a good idea.
Still,
we're going to keep trying. It simply may be that it's difficult
in nutritional supplementation to stumble upon the proper ingredients
in the right proportions to have the desired effects. Some
supplements have gained official sanction: Calcium and Vitamin D
supplements are approved to prevent bone fractures and
osteoporosis. Macular degeneration is prevented with supplements
of Vitamins E, C, beta carotene, copper, and zinc. There has been
a very big decrease in birth defects accomplished by giving pregnant
women folic acid supplements, which is Vitamin B9.
Cholesterol-lowering effects are quite clear for red rice yeast, flax seed, and oat bran. Fish oil (omega-3-fatty acids) gets high marks as a lipid-regulating agent. It is even sold at exorbitant prescription drug prices as Lovaza, from SmithKlineBeecham.
It
is important to accept the inevitable disappointments, when favored
plausible nutritional supplements are shown not to have the benefits we
had hoped. This acceptance is the only path toward nutritional
supplement enlightenment, and, step-by-step, we're making
progress. When you visit us for your physical exam, you should
ask your examining doctor your own questions about nutrition.
Avram L. Nemetz, M.D.
Medical Director
Affiliated Physicians
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