Figure 1. Chronological change in dietary intake and incidence of IBD in Japan. The daily intake per capita of rice, animal protein, and animal fat is shown in the upper panel based on the data for 35 years from 1965 to 2000 obtained by the National Nutritional Survey (35). The incidence of IBD every 5 years (Table 1) is shown in the lower panel.
Figure 2. Correlation between Crohn’s disease and ulcerative colitis in the annual numbers of new cases (A) and the annual numbers of cases (B). In Japan, national registration of ulcerative colitis and Crohn’s disease started in 1975 and 1976, respectively. A scattergram was generated based on the data for 24 years from 1977 to 2000 (29), (30), (31). The linear regression formula and correlation coefficient are shown.
Figure 3. Correlation coefficient between increase in new cases of inflammatory bowel disease and food groups, nutrients, or energy. Data from 1965 to 2000 were used. Foods, nutrients, or energy with a p value less than 0.0001 are shown in this figure, except for dietary fiber for ulcerative colitis (p < 0.001) (Table 2). The white column shows ulcerative colitis, and the black column shows Crohn’s disease.
Figure 4. Factor analysis of inflammatory bowel disease (IBD) and intake of nutrients and energy. Trends of variables are similar in both ulcerative colitis (A) and Crohn’s disease (B) (Table 4). Fat, animal protein, and animal fat were identified as promoting factors for IBD; in contrast, carbohydrates, dietary fiber, and energy were identified as prophylactic factors against IBD.