Association of B Vitamins and Methionine Intake with the Risk of Gastric Cancer: The Japan Public Health Center-based Prospective Study

Dietary intake of B vitamins and methionine might associate with carcinogenesis due to their role in DNA synthesis and methylation. Owing to the previous inconsistent findings on gastric cancer risk, we aimed to examine the associations between dietary intakes of B vitamins and methionine and the risk of gastric cancer, according to sodium intake. We included 86,820 Japanese individuals who completed a validated food frequency questionnaire with 138 food items in the Japan Public Health Center-based Prospective Study. Cox proportional hazards regression was used to obtain HRs and 95% confidence intervals (CI) of gastric cancer according to separate intakes of folate, vitamin B6, vitamin B12, and methionine after adjusting for confounding factors, including Helicobacter pylori and atrophic gastritis in the subgroup analysis. We identified 2,269 gastric cancer cases within a median of 15.4 years of follow-up. We found no association between any of the dietary intakes of folate, vitamin B6, vitamin B12, or methionine with the risk of gastric cancer. In the stratified analysis by sodium intake, we observed a positive association between folate intake and risk of gastric cancer among participants with a high sodium intake (≥4.5 g/day) [HR ¼ 1.28 (95% CI, 1.06-1.56), Ptrend ¼ 0.001; Pinteraction ¼ 0.02]. Meanwhile, there was no association between folate intake and risk of gastric cancer among participants with low sodium intake (<4.5 g/day) [HR ¼ 0.94 (95% CI, 0.73-1.21), Ptrend ¼ 0.49]. In conclusion, we found no association between any dietary intakes of folate, vitamin B6, vitamin B12, and methionine with the risk of gastric cancer. Prevention Relevance: The increased intake of B vitamins and methionine in populations with adequate dietary intake of these nutrients showed no association with the risk of gastric cancer. © 2021 American Association for Cancer Research