Dietary Iron Intake and Risk of Gastric Cancer

BACKGROUND: Iron is one of the essential elements for human life. Prior studies provided inconclusive results about the association between dietary iron intake and gastric cancer risk. We determined the association between dietary iron intake and the 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, semiquantitative food frequency questionnaire to obtain dietary information, including dietary iron intake. An unconditional regression model was used to calculate 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 with 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), respectively. This U-shaped association was also observed in both sexes, in all types of dietary iron intake (i.e., heme and nonheme), and among individuals with noncardia gastric cancer. This pattern was more apparent among individuals with a body mass index < 23 kg/m2 (Pheterogeneity = 0.02), never smokers (Pheterogeneity = 0.02), those without a family history of cancer (Pheterogeneity = 0.99), and individuals with blood group O (Pheterogeneity = 0.98) but showed up in both alcohol and coffee drinkers. CONCLUSIONS: We found a U-shaped association between dietary iron intake and gastric cancer risk. IMPACT: Results from our study also provide evidence for a tailored dietary intervention program that would benefit specific populations and those living in similar settings.