Consumption of onions and a reduced risk of stomach carcinoma.

BACKGROUND & AIMS Results from case-control studies and laboratory tests indicate that consumption of allium vegetables may considerably reduce the risk of stomach cancer. The association between onion and leek consumption, garlic supplement use, and the incidence of stomach carcinoma was studied. METHODS The association was investigated in the Netherlands Cohort Study on diet and cancer, which started in 1986 with 120,852 men and women ranging in age from 55 to 69 years. Dietary data were available for 139 stomach carcinoma cases diagnosed during 3.3 years of follow-up and for 3123 subjects of the randomly selected subcohort. RESULTS The rate ratio for stomach carcinoma in the highest onion consumption category (> or = 0.5 onions/day) was 0.50 (95% confidence interval, 0.26-0.95) compared with the lowest category (0 onions/day) after adjustment for other risk factors. The reduction in risk was restricted to carcinoma in the noncardia part of the stomach (P = 0.002) and was also found among subjects without a history of stomach disorders (P = 0.01). The consumption of leeks and the use of garlic supplements were not associated with stomach carcinoma risk. CONCLUSIONS The Netherlands Cohort Study provides evidence for a strong inverse association between onion consumption and stomach carcinoma incidence.