Dietary Iron Intake and Risk of Gastric Cancer

Abstract

Background. Iron is one of the essential elements for human life. Prior studies provided inconclusive results regarding the association between dietary iron intake and gastric cancer risk. We determined the association between dietary iron intake and risk of gastric cancer in a case-control study of 1,182 incident gastric cancer cases and 2,965 controls in Vietnam. Methods. We used a validated, semi-quantitative food frequency questionnaire to obtain dietary information, including dietary iron intake. Unconditional regression model was used to calculate odds ratio (OR) and 95% confidence intervals (95% CI) of gastric cancer in relation to dietary iron intake, adjusted for potential confounders. Results. We observed a U-shaped association between dietary iron intake and gastric cancer risk. Compared to category 2 (reference group), the ORs and 95% CIs of category 1 (lowest intake) and categories 3, 4, 5 and 6 were 1.64 (1.27-2.12), 1.17 (0.90-1.53), 1.35 (1.01-1.82), 1.65 (1.18-2.31) and 2.00 (1.36-2.95) (Ptrend<0.001). This U-shaped association was also observed in both sexes, all types of dietary iron intake (i.e., heme- and non-heme) and among individuals with non-cardia gastric cancer. This pattern was more apparent among individuals with BMI<23 kg/m2 (Pheterogeneity=0.02), never smokers (Pheterogeneity=0.02), without family history of cancer (Pheterogeneity=0.99), blood group O (Pheterogeneity=0.98); however, showed up in both alcohol-and coffee drinkers. Conclusion. We found a U-shaped association between dietary iron intake and gastric cancer risk. Impact. Results from our study also provide evidence for tailored dietary intervention program that would benefit most to specific populations and those living in similar settings.