Vitamin C: cure for the common cold?

The idea that an increased intake of vitamin C may be helpful in fighting the common cold has been around since at least the 1930s, but it was not until 1970 that the publication of Linus Pauling's best seller, Vita min C and the Common Cold, turned the issue into a public controversy. 1 As a result of the interest generated by this controversy, a number of scientifically sound experimental studies have been carried out, and although there are still unanswered questions, it is now clear that vitamin C is, unfortunately, no panacea for colds or other respiratory infections. However, even if the promise of virtual eradication of the common cold (suggested as a possibility at one point in Pauling's book) has proved unrealistic, there remains enough intriguing evidence of some interaction between this vitamin and the infectious process to suggest that it is worth investigating further and that it may have a role, however limited, in reducing the burden of this relatively trivial but annoying affliction. In trying to unravel some of the confusion and conflicting evidence over the use of vitamin C in upper respiratory infections, it is helpful to recognize that its use has been suggested either to prevent the disease from occurring or to treat it once it has occurred. These are two quite different approaches and carry with them different practical implications. If vitamin C is to be used prophy-lactically, one is faced not only with the problem of compliance (many people do not bother to take regular Terence W. Anderson, MD, PhD, is professor of epidemiology in the department of preventive medicine and biostatistics, medication when they are free of symptoms), but also with an increased possibility of side effects, since these are more likely to occur with something taken regularly for months or years than with something used only occasionally and briefly as a treatment. Two other issues of which individuals often lose sight in the rhetoric are the questions of effective dose and the basic nutritional status of the population. Thus if a daily intake of 1,000 mg of vitamin C is found to produce a beneficial effect, it is important to establish whether the same effect could be achieved with a much smaller dose, since undesirable side effects are more likely to result from large doses than small ones. Further, whatever si/e Jose is taken, it is only likely to show …