Vitamin C inhibits the growth of a bacterial risk factor for gastric carcinoma: Helicobacter pylori.

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.