PRESCRIPTIONS
Popping vitamins may be harmful

By Landis Lum

Q. My wife takes a bunch of vitamins and antioxidants every day to prevent cancers and heart disease. What do you think?

A. Well, a diet high in fruits and vegetables, and high blood levels of beta-carotene (a form of vitamin A) have been found by many studies to be associated with a reduced risk for cancers and heart disease. The belief is that it's the vitamins in fruits and vegetables that do this, and that taking these in the form of supplements should improve one's health and, the more, the better.

But that may not necessarily be true. In a kind of study called a randomized controlled trial, researchers studied more than 14,000 male and female smokers and 4,000 men who had been exposed to asbestos. The May 1996 New England Journal of Medicine reported that when the study subjects were compared with a control group who did not receive supplements, getting 30 milligrams of beta-carotene and 25,000 Units of retinol (also known as vitamin A) a day actually increased the risk of dying from lung cancer by 46 percent.

So what's happening? In fruits and vegetables there are hundreds of molecules, "vitamins" and other substances that haven't even been discovered yet; it could be that one of these — or a combination of these, taken in the correct proportion — is the true "super antioxidant" that protects against cancers and heart disease.

Beta-carotene may simply be a marker for this or some other protective component in natural foods. So, if you take extra beta-carotene, it may throw off the balance of the substances you ingest in the natural, correct proportions in your diet, causing premature death. That is another reason to avoid large doses of any supplement, such as those you find in megavitamins.

This underscores the point that promising associations — between antioxidants and preventing heart attacks, for example — found in observational studies must be tested in these stronger, more accurate randomized controlled trials. In the June 14 issue of the journal Lancet, researchers from the Cleveland Clinic analyzed eight randomized trials and found that taking beta-carotene supplements also led to increased deaths from heart disease.

This is especially concerning because the doses used (15-50 mg, or 25,000 to 80,000 Units of vitamin A activity a day) are similar to those found in store preparations.

The Cleveland researchers also analyzed seven randomized trials of vitamin E treatment in daily doses ranging from 50 to 800 IU and found that vitamin E did not reduce the risk of heart disease, strokes, or deaths from any cause. So tell your wife to at the most take a single multivitamin pill a day — not bunches of pills.

Dr. Landis Lum is a family-practice physician for Kaiser Permanente and an associate clinical professor at the University of Hawai'i's John A. Burns School of Medicine. Send your questions to Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; fax 535-8170; or write islandlife@honoluluadvertiser.com. This column is not intended to provide medical advice.