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Dietary risk factors for inflammatory bowel disease A Multicenter Case-Control Study in Japan


  • Members of the working group involved in this study were as follows: Khozho Imai and Yojiro Niitsu (Sapporo Medical University); Akihiro Munakata (Hirosaki University School of Medicine); Nobuo Hiwatashi (Sendai Red Cross Hospital); Masakazu Takazoe (Social Insurance Central General Hospital); Shingo Kameoka (Tokyo Women's Medical University); Toshio Sawada (Gunma Prefectural Cancer Center); Yasuo Suzuki (Chiba University School of Medicine); Tadao Bamba (Shiga University of Medical Science); Kazuya Makiyama (Nagasaki University School of Medicine); Norio Morita (Takano Hospital); Hirohito Tubouti (Miyazaki Medical College); and Fukunori Kinjo (University of the Ryukyus School of Medicine.


To evaluate the role of dietary factors in the etiology of inflammatory bowel disease (IBD), we conducted a multicenter hospital-based case-control study in a Japanese population. Cases were IBD patients aged 15 to 34 years [ulcerative colitis (UC) 111 patients; Crohn's disease (CD) 128 patients] within 3 years after diagnosis in 13 hospitals. One control subject was recruited for each case who was matched for sex, age, and hospital. A semiquantitative food frequency questionnaire was used to estimate preillness intakes of food groups and nutrients. All the available control subjects (n = 219) were pooled, and unconditional logistic models were applied to calculate odds ratios (ORs). In the food groups, a higher consumption of sweets was positively associated with UC risk [OR for the highest versus lowest quartile, 2.86; 95% confidence interval (CI), 1.24 to 6.57], whereas the consumption of sugars and sweeteners (OR, 2.12; 95% CI, 1.08 to 4.17), sweets (OR, 2.83; 95% CI, 1.38 to 5.83), fats and oils (OR, 2.64; 95% CI, 1.29 to 5.39), and fish and shellfish (OR, 2.41; 95% CI, 1.18-4.89) were positively associated with CD risk. In respect to nutrients, the intake of vitamin C (OR, 0.45; 95% CI, 0.21 to 0.99) was negatively related to UC risk, while the intake of total fat (OR, 2.86; 95% CI, 1.39 to 5.90), monounsaturated fatty acids (OR, 2.49; 95% CI, 1.23 to 5.03) and polyunsaturated fatty acids (OR, 2.31; 95% CI, 1.12 to 4.79), vitamin E (OR, 3.23; 95% CI, 1.45 to 7.17), and n-3 (OR, 3.24; 95% CI, 1.52 to 6.88) and n-6 fatty acids (OR, 2.57; 95% CI, 1.24 to 5.32) was positively associated with CD risk. Although this study suffers from the shortcoming of recall bias, which is inherent in most retrospective studies (prospective studies are warranted to confirm the associations between diet and IBD risk), the present findings suggest the importance of dietary factors for IBD prevention.