The November 2013 issue of the American Journal of Clinical Nutrition reports a protective effect for higher plasma vitamin C levels against gastric adenocarcinoma in Chinese men and women.
The current study involved follow-up participants in the Linxian General Population Nutrition Intervention Trial, which concluded in 1991. Blood samples collected between 1999 and 2000 were analyzed for plasma vitamin C levels. Four hundred sixty-seven men and women diagnosed with gastric adenocarcinoma and 618 subjects with esophageal squamous cell carcinoma were compared with 948 subjects who did not have the diseases.
A lower risk of gastric cancer was observed in association with higher plasma vitamin C levels. Participants with normal vitamin C levels, defined as greater than 28 micromoles per liter, had a 27% lower risk of gastric cancer in comparison with those whose levels were low at 28 micromoles per liter or less. A meta-analysis that included the current study and two other cohort studies resulted in similar findings. No association for vitamin C levels with esophageal squamous cell carcinoma was determined.
Authors Tram Kim Lam and colleagues remark that vitamin D may help protect the cells from oxidative DNA damage and other adverse effects of H. pylori infection, which is a common cause of gastric cancer. They note that H. pylori is not believed to increase the risk of esophageal squamous cell cancer, which could explain the lack of protective effect for vitamin C against this type of cancer that was observed in this study.
“This study was the largest prospective cohort study on the association between circulating vitamin C and gastric adenocarcinoma risk to date and the first prospective evaluation of the relation with esophageal squamous cell carcinoma,” they announce. “Results based on our meta-analysis of prospective cohort studies suggest that plasma vitamin C is inversely associated with gastric adenocarcinoma incidence.”