Vitamins and Stomach Cancer: A Hospital Based Case-Control Study in Iran

Background: This study investigated the association between vitamins intakes and risk of gastric cancer (GC) among Iranian population. Methods: In this hospital-based case-control study, 178 pathologically confirmed GC patients and 276 healthy controls were interviewed to answer a valid diet history questionnaire. Unconditional logistic regression, in which potential confounders were taken into account, was applied to determine the association of vitamin intakes and odds of GC in total population and in stratums of body mass index (BMI), helicobacter pylori (H-pylori) infection, and smoking. Results: GC was directly associated with vitamin D (OR 1.59; CI 95% 1.07, 2.36) and cobalamin (OR 1.25; CI 95% 1.08, 1.44). Thiamin (OR 0.50; 95%CI 0.30, 0.83), pantothenic acid (OR 0.71; 95%CI 0.58, 0.87), folate (OR 0.99; 95%CI 0.99, 0.99) and vitamin E (OR 0.98; 95%CI 0.96, 0.99) were inversely associated with GC. In 231 H-pylori infected participants, consumption of thiamin (OR 0.3; 95% CI 0.59, 0.86), pyridoxine (OR 0.52; 95%CI 0.31, 0.85), and folate (OR 0.99; 95%CI 0.99, 0.99) reduced GC risk. In H-pylori negative participants, only vitamin­ E (OR 0.96; 95%CI 0.93, 0.99) reduced the risk and vitamin D (OR 1.99; 95%CI 1.18, 3.36), riboflavin (OR 1.91; 95%CI 1.37, 2.66), pantothenic acid (OR 1.34; 95%CI 1.13, 1.64), biotin (OR 1.03; 95%CI 1.01, 1.05), and cobalamin (OR 1.36; 95%CI 1.13, 1.64) increased the risk. In BMI stratums, only vitamin D (OR 1.81; 95%CI 1.07, 3.08) was associated with the risk of GC among normal weight participants. Vitamin E was associated with lower risk of GC in ever smokers (OR 0.97; 95%CI 0.95, 0.99) and thiamin (OR 0.41; 95%CI 0.19, 0.86) and niacin (OR 0.93; 95%CI 0.87, 0.99) were associated with lower risk in never smokers. Positive associations were observed by increasing vitamin D (OR 2.08; 95%CI 1.12, 3.85) and cobalamin (OR 1.33; 95%CI 1.08, 1.65) in never smokers. Conclusion: This study provided support for a possible protective effect of vitamin E, thiamin, pantothenic acid, and folate on GC risk. Vitamin D and cobalamin intake increased the risk.