By Sean Henahan, Access Excellence

HELSINKI- A new study from Finland rekindles the debate on whether or not vitamin C benefits those suffering the symptoms of the common cold.

The new study re-assessed several well known studies including the one published more than 20 years ago that led many in the nutrition research community to conclude that vitamin C did not benefit cold sufferers.

The first reports that vitamin C might benefit the cold came in the 1930s. The idea gained much more public attention with the studies of Nobel prize winner Dr. Linus Pauling in the 1970s. Pauling's own published studies suggested that doses of one gram per day of vitamin C did reduce the incidence and severity of the common cold.

Pauling's studies stirred considerable controversy in the research community. The controversy led a researcher named Thomas Chalmers to review the effects of vitamin C on the common cold in seven placebo controlled studies in 1975 . Chalmers concluded that there was no significant difference in cold severity between people taking vitamin C or placebo. It was this study that led to the current general consensus in the medical community that vitamin C has no effect on symptoms of the common cold.

The new study by Finnish researchers suggests Chalmer's review contained significant methodological flaws. The researchers report that Chalmer's did not distinguish between dosing among different studies, combining studies using relatively low doses (0.025-0.05 grams per day) of vitamin C with studies using much higher doses, from one to six grams per day.

The original Chalmers review also contained significant errors, the University of Helsinki researchers report. For example, in one study the results from placebo and vitamin C were combined, while in another case the number of participants in a trial are miscalculated. The studies in the review also did not use standardized methods for reporting cold symptoms, the researchers report.

The Finnish researchers also question whether Chalmers applied the most appropriate statistical methods to his analysis. For example, Chalmers did not weight the individual means with the number of subjects to arrive a figure that would show mean individual difference in duration of cold symptoms. Moreover, Chalmers did not report "p-values", standard measures of probability now used in all clinical studies.

"We have shown that Chalmer's review contains serious and numerous errors. Therefore, the widely accepted notion that vitamin C does not have any significant effect on the common cold is largely based on an unreliable review," reports Harri Hemila, Ph.D., Department of Public Health, University of Helsinki, Finland, in a recent issue of the Journal of the American College of Nutrition.

Indeed, a re-analysis of the data from Chalmer's review that corrects the previous miscalculations suggests that vitamin C in doses of one gram per day did help reduce cold symptoms, reducing episode duration by 22%. Moreover, the large number of double-blind, placebo controlled studies conduced since Chalmer's influential review "consistently and persuasively" support the conclusion that vitamin C does offer some relief of cold symptoms, emphasized Dr. Hemila.

"The general belief in conventional medical circles that vitamin C has no effect on the common cold seems surprising since essentially all of then placebo controlled studies carried out both before and after Pauling's conclusions have shown a beneficial effect. We believe the current conception that vitamin C does not affect the common cold can be traced largely to the review written by Chalmers," notes Dr. Hemila.

In the 1970's there was still some concern about potential toxic effects associated with large doses of vitamin C. A careful review of controlled studies conducted since then suggests that vitamin C in doses of one gram per day is quite safe for healthy people. Indeed it appears that people with common cold infections can eat as much as 30 grams per day of vitamin C because of apparent changes in vitamin C metabolism. However, gastrointestinal disturbances including diarrhea have been reported by healthy people taking four grams of vitamin C per day, Dr. Hemila reports.

Recent studies also provide a physiological rationale for the use of vitamin C against infection. For example, vitamin C appears to protect against the reactive oxygen species produced by phagocytes during a viral infection. Vitamin C also appears to enhance the proliferative responses of T-lymphcytes, as well as increasing production of interferon, he noted.

For more information on this area of research, see:

1. Hemila, H.- Journal of the American College of Nutrition (Vol. 14, No.2, 1995).

2. Pauling, L.- Vitamin C and the Common Cold, San Francisco, Freeman, 1970.

3.Chalmers, T- Am. Journal of Medicine (58:532-536, 1975).

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