Interaction between dietary nutrients related to one-carbon metabolism intakes and AHCY rs819173 polymorphism in the risk of gastric cancer: a case-control study in Korea.

B vitamin and methionine intake may influence cancer development, but their link to gastric cancer (GC) risk is unclear. Nutrients related to one-carbon metabolism (OCM) have been shown to be associated with S-adenosylhomocysteine hydrolase (AHCY), one of the most crucial enzymes in OCM, which is regulated by the AHCY gene. Thus, we hypothesised that a higher intake of total nutrients related to OCM may reduce the risk of GC, and this preventative effect may interact with the AHCY rs819173 polymorphism. We conducted a case–control study at the National Cancer Center in Korea, involving 371 cases and 738 controls, aiming to determine the interaction between the AHCY rs819173 polymorphism and nutrients related to OCM intakes in GC risk. Dietary vitamin B and methionine intakes were collected using semi-quantitative FFQ (SQFFQ). The OR and 95 % CI were calculated using unconditional logistic regression models. Higher intake of total nutrients related to OCM was found to be inversely associated with GC risk (adjusted OR (aOR) = 0·57, 95 % CI 0·37, 0·86, P_{for trend} = 0·009). No significant association between the AHCY rs819173 polymorphism and GC risk was found. In the dominant model of AHCY rs819173, participants with major homozygous (TT) and higher intake of nutrients related to OCM had a lower GC risk than those with lower intake (aOR = 0·49, 95 % CI 0·30, 0·81, P interaction = 0·015). Higher intakes of total vitamin B and methionine were proposed as potential protective nutrients against GC. Moreover, this association might be influenced by the presence of the AHCY rs819173 polymorphism.