The Role of Vitamin C in the Treatment of the Common Cold
Dr Harri Hemila MD PhD co author of the Cochrane Review article replies :
The Cochrane review was limited to placebo-controlled trials in which at least 0.2 g of vitamin C was used per day. Most of these trials examined vitamin C administration as regular supplementation and provided strong evidence that vitamin C shortens the duration of colds and alleviates its symptoms. Children benefited more than adults. The data also suggested that high doses of vitamin C are more beneficial than low doses.[2-6]
Stratification of the regular supplementation trials in children by vitamin C dosage shows a tendency for dose dependency. Four trials, using 0.20 to 0.75 g of vitamin C per day, found an average reduction of 7 percent in common cold duration (95% confidence interval [CI], -19 to 5). Six trials with 1 g of vitamin C per day found an average reduction of 18 percent (95% CI, -32 to -3), and two trials using 2 g of vitamin C per day found an average reduction of 25 percent (95% CI, -50 to 0.1). Therefore, the 13.6 percent estimate for common cold reduction we calculated in the Cochrane review , based on all 12 trials with children who received at least 0.2 g of vitamin C per day, may underestimate the effect of high doses.
Extracted from a letter published in The American Academy of Family Physicians Oct 15th 2007 View letter
1. Simasek M, Blandino DA. Treatment of the common cold. Am Fam Physician 2007;75:515-20.
2. Douglas RM, Hemilä H, D’Souza R, Chalker EB, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 2004;(4):CD000980.
3. Karlowski TR, Chalmers TC, Frenkel LD, Kapikian AZ, Lewis TL, Lynch JM. Ascorbic acid for the common cold. A prophylactic and therapeutic trial. JAMA 1975;231:1038-42.
4. Hemilä H. Vitamin C, the placebo effect, and the common cold: a case study of how preconceptions influence the analysis of results. J Clin Epidemiol 1996;49:1079-84.
5. Hemilä H. Vitamin C supplementation and common cold symptoms: factors affecting the magnitude of the benefit. Med Hypotheses 1999;52:171-8.
6. Hemilä H. Do vitamins C and E affect respiratory infections? [Academic Dissertation] University of Helsinki, Helsinki, Finland, January 2006:21-7, 36-45, 48-9, 62-3. Accessed August 6, 2007: view paper
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28th March 2015
This one day event is designed to explore some of the clinically relevant evolving events in microbiology, mucosal immunity and functional medicine as it relates to inflammation and health. The presenters are well known for their many years of work in research, analysis, practice and lecturing. They will present substantive evidence of these evolving trends and how they impact on clinical decisions, describing where evidence is preliminary, novel, or of greater substantiation. The day will have a strong clinical bias and provide a welcome opportunity for questions and answers.Click for further information
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