Vitamins, carotenoids, dietary fiber, and the risk of gastric carcinoma: results from a prospective study after 6.3 years of follow-up.

BACKGROUND Numerous components of fruit and vegetables are considered to decrease the risk of gastric carcinoma. In the current prospective study, the authors examined the association between the intake of vitamins, carotenoids, and dietary fiber and vitamin supplement use and the incidence rate of gastric carcinoma. METHODS The Netherlands Cohort Study began in 1986 with 120,852 men and women ages 55-69 years. Data regarding diet and other covariates were collected by means of a self-administered questionnaire. After 6.3 years of follow-up, data regarding 282 incident cases of gastric carcinoma and 3123 subcohort members were available for case-cohort analyses. RESULTS In analyses adjusted for age, gender, smoking history, education, stomach disorders, and family history of gastric carcinoma, an inverse association with vitamin C intake (relative risk [RR] for highest vs. lowest intake category, 0.7; 95% confidence interval [95% CI], 0.5-1.0) was observed, with a borderline significant trend across three intake categories (P = 0. 06). After the exclusion of cases diagnosed in the first and second follow-up years, the RR was 0.9 (95% CI, 0.6-1.2; P trend = 0.44). Intake of retinol and beta-carotene were associated positively with gastric carcinoma risk with highest versus lowest quintile RRs of 1. 6 (95% CI, 1.0-2.5; P trend = 0.02) and 1.6 (95% CI, 1.0-2.6; P trend = 0.13), respectively, after the exclusion of first-year and second-year cases. Intake of folate, vitamin E, alpha-carotene, lutein plus zeaxanthin, beta-cryptoxanthin, lycopene, and dietary fiber was not associated with gastric carcinoma. Patients who used vitamin A-containing supplements had a lower risk of gastric carcinoma than nonusers (RR = 0.4; 95% CI, 0.2-0.9). CONCLUSIONS No clear inverse associations were found between the intake of vitamins, carotenoids, and dietary fiber and the risk of gastric carcinoma after adjustment for confounding variables and the exclusion of first-year and second-year cases.