No preventive effect of dietary fiber against colon cancer in the Japanese population: A cross-sectional analysis

The report of Fuchs et al. in 1999 on the protective effects of dietary fiber (DF) against colon carcinogenesis has led many researchers to question the benefits of DF. We analyzed the relationship between dietary intake and mortality from colon cancer in Japan cross-sectionally. Dietary data were taken from the National Nutrition Survey. The standardized mortality ratio (SMR) was calculated using data from "Vital Statistics" and "the Population Census in Japan." Multiple regression analysis (stepwise variable selection method) was performed with the SMR of colon cancer as the objective variable and intake of DF, nutrients, and food groups in 1966 as the explanatory variables. The beta regression coefficient was significantly positive for intakes of fat, protein, and vitamin C and significantly negative for intakes of calcium and vitamin A to the SMR of colon cancer However, no significant correlation was observed for DF or for any of the various food groups analyzed. In conclusion, our data do not demonstrate any protective effect of DF on colon cancer in subjects with a low fat intake (Japanese subjects), which supports Fuchs' findings in subjects with high fat intake (U.S. subjects).