Dietary intake of vegetables, fruit, and antioxidants and risk of ulcerative colitis: A case-control study in Japan

Objectives: Oxidative stress is considered one of the etiologic factors involved in ulcerative colitis (UC), yet there is limited epidemiologic information regarding the relationship between antioxidant intake and the risk of UC. The aim of the present case-control study in Japan was to examine the association between intake of green and yellow vegetables, other vegetables, fruit, vitamin C, vitamin E, retinol, alpha-carotene, beta-carotene, and cryptoxanthin and UC risk. Methods: A total of 384 cases within 4 y of diagnosis with UC and 665 controls were included in the study. Data on dietary intake and confounders were obtained using a self-reported questionnaire. Information on dietary factors was collected using a 169-item semiquantitative food-frequency questionnaire. Adjustment was made for sex, age, pack-y of smoking, alcohol consumption, history of appendicitis, family history of UC, education level, and body mass index. Results: Higher intake levels of other vegetables, vitamin C, and retinol were independently associated with a reduced risk of UC. The adjusted odds ratio between extreme quartiles was 0.51 (95% confidence interval [CI], 0.34−0.76; P for trend ≤ 0.001) for other vegetables, 0.45 (95% CI, 0.30−0.69, P for trend ≤ 0.001) for vitamin C, and 0.64 (95% CI, 0.43−0.95, P for trend = 0.04) for retinol. There were no associations between intake of green and yellow vegetables, fruit, vitamin E, alpha-carotene, beta-carotene, or cryptoxanthin and UC risk (P for trend = 0.29, 0.56, 0.89, 0.20, 0.69, and 0.22, respectively). Conclusions: Intake of other vegetables, vitamin C, and retinol was inversely associated with UC risk.