Background/objectives: Gastric cancer is one of the leading malignancies worldwide. B vitamins play important roles in DNA synthesis and methylation because they are considered co-enzymes in one-carbon metabolism. There is inconclusive evidence regarding the associations between dietary vitamins B1, B2, and B6 with the risk of gastric cancer in different epidemiologic studies. We, therefore, investigated such associations in a hospital-based case-control study comprising 1182 incident cases of gastric cancer and 2995 controls in Vietnam.
Methods: Dietary vitamins B1, B2, and B6 were derived from a semi-quantitative validated food frequency questionnaire. An unconditional logistic regression model was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for the risk of gastric cancer in relation to dietary intake of vitamins B1, B2, and B6.
Results: Overall, dietary vitamins B1 (ORper-SD increment = 0.83; 95% CI: 0.78-0.89; Ptrend < 0.001) and B6 (ORper-SD increment = 0.88; 95% CI: 0.81-0.94; Ptrend < 0.001) were associated with a reduced risk of gastric cancer. Compared with the lowest quintile, the ORs (95% CIs) of gastric cancer for quintiles 2, 3, 4, and 5 of the vitamin B1 intake were 0.64 (0.51-0.79), 0.54 (0.43-0.69), 0.57 (0.44-0.74), and 0.42 (0.31-0.55), respectively; for vitamin B6 intake, quintiles 2, 3, 4, and 5 were 0.53 (0.42-0.66), 0.54 (0.42-0.70), 0.61 (0.46-0.81), and 0.46 (0.33-0.63), respectively. This inverse association was not different across sex, BMI, and smoking statuses. No association was found between dietary vitamin B2 and gastric cancer risk.
Conclusions: Dietary vitamins B1 and B6 were associated with a reduced risk of gastric cancer in the Vietnamese population. Future studies are warranted to replicate our findings, which also have great implications for gastric cancer prevention and control programs in low- and middle-income countries.
Keywords: Vietnam; case-control study; dietary intake; gastric cancer; risk factor; vitamin B2; vitamin B6; vitamins B1.