Narrow Scope of Vitamin C Review
http://www.100md.com
《科学公立图书馆医学》
1 Knowledge of Health San Dimas, California, United States of America
Covering 60 years of research without mentioning a paper that highlights flaws in the literature, in a review, should negate any conclusion. In the Cochrane review by Douglas et al. [1], which is referenced in the Best Practice article by Douglas and Hemil [2], there was no mention of the revealing paper published last year by Padayatty et al. [3], which shows that three-times greater blood concentration can be achieved with an oral dose of vitamin C than previously thought possible. Since viruses increase the demand for ascorbic acid, the oral doses used in the reviewed studies appear trivial, and would not be expected to produce any positive effect. Compare human oral dose studies to what animals synthesize throughout the day. It is obvious that a single dose of a water-soluble vitamin, regardless of the number of milligrams consumed, will not elevate blood plasma levels enough to produce a preventive or therapeutic effect.
References
Douglas RM, Hemil H, D'Souza R, Chalker EB, Treacy B (2004) Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 4:CD000980 pub2.
Douglas RM, Hemil H (2005) Vitamin C for preventing and treating the common cold. PLoS Med 2:e168 DOI: 10.1371/journal.pmed.0020168.
Padayatty SJ, Sun H, Wang Y, Riordan HD, Hewitt SM, et al. (2004) Vitamin C pharmacokinetics: Implications for oral and intravenous use. Ann Intern Med 140:533–537.(William Sardi)
Covering 60 years of research without mentioning a paper that highlights flaws in the literature, in a review, should negate any conclusion. In the Cochrane review by Douglas et al. [1], which is referenced in the Best Practice article by Douglas and Hemil [2], there was no mention of the revealing paper published last year by Padayatty et al. [3], which shows that three-times greater blood concentration can be achieved with an oral dose of vitamin C than previously thought possible. Since viruses increase the demand for ascorbic acid, the oral doses used in the reviewed studies appear trivial, and would not be expected to produce any positive effect. Compare human oral dose studies to what animals synthesize throughout the day. It is obvious that a single dose of a water-soluble vitamin, regardless of the number of milligrams consumed, will not elevate blood plasma levels enough to produce a preventive or therapeutic effect.
References
Douglas RM, Hemil H, D'Souza R, Chalker EB, Treacy B (2004) Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 4:CD000980 pub2.
Douglas RM, Hemil H (2005) Vitamin C for preventing and treating the common cold. PLoS Med 2:e168 DOI: 10.1371/journal.pmed.0020168.
Padayatty SJ, Sun H, Wang Y, Riordan HD, Hewitt SM, et al. (2004) Vitamin C pharmacokinetics: Implications for oral and intravenous use. Ann Intern Med 140:533–537.(William Sardi)