Vitamin C and SARS coronavirus

Harri Hemilä*

Department of Public Health, University of Helsinki, Helsinki, FIN-00014 Finland

Keywords: ascorbic acid, pneumonia, severe acute respiratory syndrome

Sir,

Recently, a new coronavirus was identified as the cause of the severe acute respiratory syndrome (SARS).1 In the absence of a specific treatment for SARS, the possibility that vitamin C may show non-specific effects on severe viral respiratory tract infections should be considered. There are numerous reports indicating that vitamin C may affect the immune system,2,3 for example the function of phagocytes, transformation of T lymphocytes and production of interferon. In particular, vitamin C increased the resistance of chick embryo tracheal organ cultures to infection caused by an avian coronavirus.4 Studies in animals found that vitamin C modifies susceptibility to various bacterial and viral infections,3 for example protecting broiler chicks against an avian coronavirus.5 Placebo-controlled trials have shown quite consistently that the duration and severity of common cold episodes are reduced in the vitamin C groups,3 indicating that viral respiratory infections in humans are affected by vitamin C levels. There is also evidence indicating that vitamin C may affect pneumonia.3 In particular, three controlled trials with human subjects reported a significantly lower incidence of pneumonia in vitamin C-supplemented groups,6 suggesting that vitamin C may affect susceptibility to lower respiratory tract infections under certain conditions. The possibility that vitamin C affects severe viral respiratory tract infections would seem to warrant further study, especially in light of the recent SARS epidemic.

Footnotes

* Tel: +359-0-191-27573; Fax: +358-0-191-27570; E-mail: harri.hemila{at}helsinki.fi Back

References

1 . Holmes, K. V. (2003). SARS-associated coronavirus. New England Journal of Medicine 348, 1948–51.[Free Full Text]

2 . Leibovitz, B. & Siegel, B. V. (1981). Ascorbic acid and the immune response. Advances in Experimental Medicine and Biology 135, 1–25.[ISI][Medline]

3 . Hemilä, H. & Douglas, R. M. (1999). Vitamin C and acute respiratory infections. International Journal of Tuberculosis and Lung Diseases 3, 756–61.

4 . Atherton, J. G., Kratzing, C. C. & Fisher, A. (1978). The effect of ascorbic acid on infection of chick-embryo ciliated tracheal organ cultures by coronavirus. Archives of Virology 56, 195–9.[ISI][Medline]

5 . Davelaar, F. G. & Bos, J. (1992). Ascorbic acid and infectious bronchitis infections in broilers. Avian Pathology 21, 581–9.[ISI]

6 . Hemilä, H. (1997). Vitamin C intake and susceptibility to pneumonia. Pediatric Infectious Diseases Journal 16, 836–7.[CrossRef][ISI][Medline]