Copyright © 1995 by Jack Challem, The Nutrition Reporter™
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Much of the skepticism surrounding the use of vitamin C in treating common colds derives from a 20-year-old meta-analysis of seven vitamin studies. This analysis by Thomas Chalmers, MD, reported that supplemental vitamin C had few if any benefits. (See Chalmers, T., American Journal of Medicine, 1975;58:532-6). Many physicians have assumed that Chalmers' study contradicted the benefits Nobel laureate Linus Pauling, PhD, reported in an earlier meta analysis, and Chalmers' study has been cited twice as often as Pauling's in the medical literature.
Even though almost 21 studies since 1971 have confirmed the benefits of high-dose vitamin C in the common cold, medicine has been less than enthusiastic in recommending it. So Harri Hemilä, PhD, of the University of Helsinki, Finland, re-analyzed Chalmers' original data. He found that Chalmers' analysis contained serious errors and omissions of data. And using all the original data Chalmers had, Hemilä calculated that large doses of vitamin C did reduce the severity of symptoms and the length of common cold infections.
"Chalmers' review of vitamin C and the common cold has been a cornerstone for the belief that the vitamin has no significant effects in reducing the severity of the common cold. The review has been used in several monographs as the basis for the conclusion that vitamin C is worthless for the treatment of the common cold," Hemilä wrote in the Journal of the American College of Nutrition (April 1995;14:116-123.)
Hemilä found numerous "erroneous and misleading numerical values" in Chalmers' analysis. But, points out Hemilä, Chalmers did not take into account what may be the most important variable: the amount of vitamin C given to subjects. Whereas Pauling had looked at studies in which people were given at least 1 gram (1,000 mg) of vitamin C daily, Chalmers included studies in which as little as 250 mg were given. "Studies using at least 1 gram/day of vitamin C show quite a consistent benefit, whereas studies with smaller doses show less consistent results."
The greatest amelioration of common cold symptoms occurred in people taking 2 to 6 grams of vitamin C daily, and the majority of studies on vitamin C and the common cold "consistently and persuasively support the conclusion that vitamin C supplementation alleviates the symptoms of the common cold," Hemilä added. It's an easy and inexpensive way, he observed, to reduce the most common cause of absenteeism from work and school.
In the same issue of the Journal of the American College of Nutrition (April 1995,14:124-136), Adrianne Bendich, PhD, FACN, a researcher at Hoffman La-Roche Inc., reviewed the medical literature describing the health benefits of vitamin C with respect to the prevention of cancer, cardiovascular disease, and cataracts. The evidence overwhelmingly points to the value of vitamin C in maintaining health and preventing these diseases. "The associations between high intake of vitamin C (and other antioxidant vitamins) and lowered disease risk are at least as strong as associations with established risk factors such as dietary fat intake," Bendich wrote.
She noted that the most recent survey of nutrient intake in the United States "found that the median vitamin C intakes were 73 mg/day for men and 66 mg/day for women." The median number, of course, is the midpoint, meaning that half the people consumed more and half consumed less. (The RDA for vitamin C is 60 mg.) In fact, 25 percent of the people surveyed ate only 39 mg/day and 10 percent consumed only 25 mg/day. In addition, only 17 percent of Americans take multivitamin supplements on a daily basis, and only 7.6 percent take vitamin C supplements.
In an editorial by John H. Weisburger, PhD, MD (pp 109-111). "The main emphasis of the late Linus Pauling was that the conventional RDA of 60 mg of vitamin C was far too low. Rather, Pauling developed the theme that grams of vitamin C per day were more likely to produce optimal effects in health maintenance and promotion....There is increasing support for the new concept that optimal nutrition and optimal defense systems...ward off not only infectious diseases but chronic diseases such as risk of coronary heart disease and several types of cancer..." Weisburger wrote.
This article originally appeared in The Nutrition Reporter™ newsletter. The information provided by Jack Challem and The Nutrition Reporter™ newsletter is strictly educational and not intended as medical advice. For diagnosis and treatment, consult your physician.