HELSINKI, FINLAND. The effect of vitamin C on the common cold has been a matter of considerable controversy ever since the early 1970s when Linus Pauling suggested that vitamin C supplementation could prevent or ameliorate the symptoms of a cold. Some subsequent studies have confirmed Dr. Pauling's findings while others have found no beneficial effects. Dr. Harri Hemila of the Finnish Department of Public Health has just released a comprehensive report which analyzes the results of 23 studies involving supplementation with 1 gram/day or more of vitamin-C. Dr. Hemila concludes that regular supplementation with vitamin C (more than 1 gram/day) does indeed decrease the severity of a cold. The beneficial effect is considerably more pronounced among children than among adults and increases with increasing intake. In five studies evaluating the effect of supplementation with 1 gram/day in adults the average reduction in cold severity was only 6 per cent. However, when 2 grams/day was administered to children a reduction of 26 per cent was observed. It is also clear that the effect is highly dose dependent. Dr. Hemila estimates that it would take 10 grams/day of vitamin C (regular supplementation) to reduce cold severity in adults by 50 per cent whereas children would only need 3.9 grams/day to achieve the same effect. Although only a few studies have been done on the effects of initiating vitamin supplementation once the cold starts (therapeutic supplementation) it would appear that the benefits of a five-day therapeutic regimen may be similar to that of continuous supplementation. Dr. Hemila urges further studies to determine the optimum doses for therapeutic supplementation which would probably range somewhere between 10 and 30 grams/day for adults. (54 references)
Hemila, H. Vitamin C supplementation and common cold symptoms: factors affecting the magnitude of the benefit. Medical Hypotheses, Vol. 52, No. 2, 1999, pp. 171-78