Nitrate intake relative to antioxidant vitamin intake affects gastric cancer risk: a case-control study in Korea

The objective of this study was to determine whether the intake of nitrate relative to antioxidant vitamin rather than absolute intake of nitrate affects the risk of gastric cancer (GC). In a case-control study in Korea using a food frequency questionnaire, trained dietitians interviewed 136 GC cases and an equal number of controls matched by sex and age. As an index of nitrate intake relative to antioxidant vitamins intake, we calculated the nitrate:antioxidant vitamin consumption ratio. The mean daily nitrate intake from foods was very high in our subjects. Higher absolute intake of nitrate was not associated with GC risk [odds ratios (OR) = 1.13; 95% confidence interval (CI) = 0.42-3.06]. However, the GC risk distinctly increased as the nitrate:antioxidant vitamin consumption ratio increased, particularly with higher nitrate:vitamin E (OR = 2.78; 95% CI = 1.01-7.67) and nitrate:folate ratios (OR = 3.37; 95% CI = 1.28-8.87). Therefore, GC risk was influenced by the intake of nitrate relative to antioxidant vitamins. Our results suggest that a decrease in the intake of nitrate relative to antioxidant vitamins is considerably more effective in reducing GC risk than either a lower absolute intake of nitrate or a higher intake of antioxidant vitamins alone.