Dietary and other risk factors of ulcerative colitis. A case-control study in Japan. Epidemiology Group of the Research Committee of Inflammatory Bowel Disease in Japan.

A multisite, hospital-based, case-control study examined the risk of ulcerative colitis in relation to dietary factors, smoking and drinking habits, past history of diseases, and childhood factors. Information was obtained from self-administered patient questionnaires. Study subjects included 101 ulcerative colitis patients who were 10-39 years old at the time of disease onset, which was within the previous 3 years, and 143 control subjects. Combined consumption of Western foods (bread for breakfast, butter, margarine, cheese, meats, and ham and sausage) was significantly related to an increased risk of ulcerative colitis (trend, p = 0.04). Margarine (as an individual Western food item) was positively associated with ulcerative colitis (trend, p = 0.005). There was also a tendency toward positive association of bread for breakfast with ulcerative colitis (trend, p = 0.07). The risk did not measurably vary with the consumption of typical Japanese foods, vegetables and fruits, confectioneries, or soft drinks. As compared with lifelong nonsmokers, current smokers tended to have a decreased risk of ulcerative colitis and former smokers had an increased risk. There was no association between breastfeeding in infancy and the risk of ulcerative colitis.