PRESCRIPTIONS
Benefits of vitamin C supplements not certain
By Landis Lum
Q. I take anti-oxidants and vitamin C to help prevent cancers and improve health. You said in your kidney stone article earlier this month not to take vitamin C, but my research says that vitamin C is OK and does not increase kidney stones. What's the scoop?
A. You're quite correct — after doing further research, it looks like taking 2 to 4 grams of vitamin C a day does not increase kidney stone formation. However, I did come across the largest trial in the world of antioxidant vitamins and cholesterol-lowering therapy in people with diabetes, heart disease and others at higher-than-average risk of heart disease.
The study appeared July 6 in the journal Lancet and was especially powerful because of its randomized design that controls for potential "confounders," such as socioeconomic status and exercise level, that so often lead to the false conclusions of the usual observational studies.
Starting in 1994, 20,536 English citizens were given either 40 mg a day of simvastatin (Zocor), a cholesterol-lowering pill, or a dummy placebo pill. In addition, within each of these two groups, half were given antioxidant vitamins (600 mg E, 250 mg C and 20 mg beta-carotene daily), and half received placebo capsules.
After all, by eliminating all those nasty free radicals, you'd expect to see a substantial decrease in cancers and heart disease with the use of antioxidants. However, after five years, the antioxidants did not reduce heart disease, cancer, death or anything else. On the other hand, taking Zocor daily resulted in substantial decreases in death rates, strokes, heart attacks and bypass surgeries of the heart or legs. In the placebo group, 707 people died from heart disease, compared to 587 in the Zocor group. And the Zocor group did not experience any increased frequency of cancers or hospitalizations for even nonheart-disease causes.
Many experts feel that Lovastatin and other "statin" drugs are as good as Zocor. But what about taking vitamin C for colds? The Cochrane Database, a highly reputable source, found that vitamin C in doses as high as one gram daily for several winter months did not reduce the occurrence of colds, though when used to treat colds, it may possibly reduce their length by 8 to 9 percent (slightly less than half a day). However, the latter may simply be from "publication bias" — namely, the tendency for studies to be published only if they show benefit (like fewer colds).
Bottom line: Get your antioxidants from natural sources such as fruits and vegetables, and don't be afraid of pills like statins if you smoke, have diabetes or are advised to start them by your doctor.
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.
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