The Vitamin C Myth
LINDA WERTHEIMER, host:
And now to the myth about vitamin C and its effect on the common cold. The health benefits of vitamin C are great, but, as it turns out, only in minimal quantities.
NPR's Patricia Neighmond explains.
PATRICIA NEIGHMOND reporting:
It was Noble Prize Winner Linus Pauling, a chemist, who really popularized vitamin C in the early 60s. He suggested that the vitamin, already known to protect against scurvy, was even more beneficial in mega doses. Dr. Marvin Lipman is an endocrinologist in New York and Chief Medical Advisor for the magazine Consumer Reports.
Dr. MARVIN LIPMAN (Endocrinologist and Consumers Union's Chief Medical Advisor): There's very little evidence available that shows that vitamin C in mega doses is good for anything.
NEIGHMOND: Lipman characterizes the taking of mega doses of vitamin C as one of the greatest hoaxes ever played on the American public.
Dr. LIPMAN: There have been at least twenty well controlled studies on the use of mega doses of vitamin C in the prevention of colds, the treating the duration of colds, and in treatment of the severity of colds, and in none of those instances has there been any, really good evidence that vitamin C in mega doses does anything.
NEIGHMOND: Part of the confusion over vitamin C probably revolves around the idea that if something is good, more is better. Vitamin C is good for the body. Lipman:
Dr. LIPMAN: Without vitamin C, the immune function deteriorates, the intercellular cement deteriorates, the linings of blood vessels deteriorate, the membranes of cells deteriorate...
NEIGHMOND: Vitamin C helps decrease the formation of arterial plaque. It also eats up free radicals, which can damage DNA and cause cancer, and if the body gets an infection it mobilizes white cells to fight the infection. But all these benefits occur at what's referred to as optimal levels of vitamin C, which is the RDA or recommended dietary allowance set by the Institute of Medicine. That's 75 milligrams for women and 90 milligrams for men.
Dr. Andrew Weil is a Professor at the University of Arizona, and has written extensively on health and nutrition. Like many Americans, for years he thought mega doses of vitamin C, 1000 milligrams a day or more, were helpful.
Dr. ANDREW WEIL (Author and University of Arizona Professor): What really convinced me to lower my recommendations were two studies, I think this was about four or five years ago, but one of them was done by the Linus Pauling Institute. And they concluded that tissues can't use more than 200 milligrams a day.
NEIGHMOND: Both Dr. Weil and Lipman agree the RDA should be increased to 200 milligrams a day. Because we don't make vitamin C on our own, we have to get it from outside the body. Supplements are one way, but fruits and vegetables are better, because the body absorbs vitamins from food more efficiently.
Consumer Reports' Dr. Lipman.
Dr. LIPMAN: In the studies that we've done, strawberries are the highest in vitamin C content, followed by oranges, cantaloupes, kiwis, black currents and grapefruit. While with vegetables, the exotic bell peppers, and by exotic I mean the colors other than green, the red, the orange, the yellow bell peppers are very high in vitamin C, about 95 milligrams per half a cup.
NEIGHMOND: For himself, Lipman says he takes no vitamin C supplements at all. He says he eats a healthful diet. So does Dr. Weil. But occasionally, says Weil, he succumbs.
Dr. WEIL: If I feel a cold starting, I might take a packet of that, you know, that EmergenC that's 1,000 milligram carbonated, fruit flavored dose. And, maybe it's a placebo, but I feel that sometimes it works for me, and, you know, I may do that, and I'm a physician. So, I think there are many people who do that just because it's a kind of folk medicine in this country.
NEIGHMOND: And luckily, there are no really dangerous side effects from taking too much vitamin C--only flatulence and diarrhea.
Patricia Neighmond, NPR News.