Vitamin C and the common cold: a retrospective analysis of Chalmers' review.

Abstract

In 1975 Thomas Chalmers analyzed the possible effect of vitamin C on the common cold by calculating the average difference in the duration of cold episodes in vitamin C and control groups in seven placebo-controlled studies. He found that episodes were 0.11 +/- 0.24 (SE) days shorter in the vitamin C groups and concluded that there was no valid evidence to indicate that vitamin C is beneficial in the treatment of the common cold. Chalmers' review has been extensively cited in scientific articles and monographs. However, other reviewers have concluded that vitamin C significantly alleviates the symptoms of the common cold. A careful analysis of Chalmers' review reveals serious shortcomings. For example, Chalmers did not consider the amount of vitamin C used in the studies and included in his meta-analysis was a study in which only 0.025-0.05 g/day of vitamin C was administered to the test subjects. For some studies Chalmers used values that are inconsistent with the original published results. Using data from the same studies, we calculated that vitamin C (1-6 g/day) decreased the duration of the cold episodes by 0.93 +/- 0.22 (SE) days; the relative decrease in the episode duration was 21%. The current notion that vitamin C has no effect on the common cold seems to be based in large part on a faulty review written two decades ago.

• Authors: H Hemilä, Z S Herman
• Journal: Journal of the American College of Nutrition (J Am Coll Nutr) Vol. 14 Issue 2 Pg. 116-23 (Apr 1995) ISSN: 0731-5724 [Print] United States
• PMID: 7790685 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Placebos
• Ascorbic Acid

Topics

• Ascorbic Acid (administration & dosage, therapeutic use)
• Common Cold (drug therapy, prevention & control)
• Controlled Clinical Trials as Topic
• Humans
• Meta-Analysis as Topic
• Placebos