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BACKGROUND: Helicobacter pylori infection is a risk factor for gastric carcinogenesis. High dietary vitamin C intake appears to protect against gastric carcinoma. It has been suggested that vitamin C exerts the protective effect by scavenging free radicals that may be enhanced by H. pylori. However, vitamin C has not been investigated in relation to the direct action on H. pylori. In this study, the authors attempted to clarify this possibility both in vitro and in vivo. METHODS: Susceptibility testing of H. pylori (64 strains) was performed by the agar dilution method. Bactericidal actions were determined by a broth cultivation technique. The effect of vitamin C on in vivo H. pylori colonization was evaluated by using the Mongolian gerbil model. RESULTS: At concentrations of 2048, 512, and 128 microg/mL (minimum inhibitory concentrations MICs), vitamin C could inhibit the growth of 90% of the bacterial stains incubated at pH values of 7.4, 6.0, and 5.5, respectively. The broth cultures exposed to the MICs of vitamin C displayed a 1.57 approximately 2.5-log decrease in the number of viable bacteria, and the loss of viability was observed in 24 hours at concentrations 8-fold higher than the MICs. In an in vivo experiment, H. pylori colonies decreased significantly in animals treated with vitamin C after oral administration of vitamin C (10 mg/head/day) for 7 days. CONCLUSIONS: High doses of vitamin C inhibit the growth of H. pylori in vitro as well as in vivo.
Zhang et al. (Sat,) studied this question.