Vitamin C: Do High Doses Prevent Colds?

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Charles W. Marshall, Ph.D. (Edited by Stephen Barrett, M.D)

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Few things have stirred the imagination and hopes of the public in matters of nutrition or vexed nutrition scientists as much as Linus Pauling's 1970 book, Vitamin C and the Common Cold. The book's main claim was that taking 1 gram (1,000 mg) of vitamin C daily would reduce the incidence of colds by 45% for most people, but that some persons might need much larger amounts. It recommended that if symptoms of a cold do start, you should take 500 or 1,000 mg every hour for several hours -- or 4 to 10 grams daily if symptoms don't disappear with smaller amounts. Without question, publication of this book, combined with Pauling's reputation as a Nobel Prize-winning scientist, has made vitamin C a best seller. When his theory was announced, millions of Americans rushed to try it for themselves. The second edition of the book, issued in 1976 as Vitamin C, the Common Cold and the Flu, suggested even higher dosages .

Vitamin C and the Common Cold also suggested that most people need a daily vitamin C intake of 2,300 mg or more for "optimum" health and to meet stresses, including infections. In a subsequent book, How to Live Longer and Feel Better, Pauling stated that individual biochemical variability is so great that optimum intake may may be as great as from 250 mg to 20 grams or more per day .

Many concerned persons have wondered whether Pauling's advice was prudent, and millions have experimented upon themselves to see whether they could tell. Pauling himself reportedly took 12,000 mg daily and raised it to 40,000 mg when symptoms of a cold appeared! Pauling apparently adapted to such dosage, but most people would suffer chronic diarrhea and the risk of kidney stones. Also, the vast majority of reputable medical and nutritional scientists strongly disagree with him. Before looking at the experimental evidence, let's discuss how scientists form their opinions.
How Scientific Facts Are Determined