Objectives: Incidence rates for
colorectal cancer are universally high in western countries while values in the orient are very variable. Japan is one of the oriental countries with a high incidence but any association with food components remains to be clarified. To explore specific nutrient effects on risk of
colorectal cancer in Japan, we here conducted a correlation analysis between change in the diet and incidence rates. Methods: Incidence data for 1976-1996 and national values for per capita daily food nutrient intake in 1956-1995 were used. We first analyzed chronological changes of food nutrients and
colorectal cancer, and then calculated correlation coefficients with time lags of 5, 10, 15 or 20 years. To adjust for the confounding effects of total energy, we also performed a partial correlation analysis. Results: Incidences of
colorectal cancer gradually increased during 1976-1996 with the highest incidence rates for colon and
rectal cancers, 25.31 and 13.75 per 100,000, respectively, in 1996. Food nutrient intake also demonstrated major variation during 1956-1995, total
fats and
oils increasing most, followed by animal
protein and animal
fats. Incidences of
colorectal cancer were positively associated with fat and oil intake, of both plant and animal types; a positive link was noted with animal
protein but the association with
plant protein consumption was inverse, as was also the case for
carbohydrate and cereals; no simple association was evident with total energy intake. Conclusions: Food nutrients play roles in risk of colon and
rectal cancers. Lower animal
protein and fat intake, and higher
carbohydrate and cereal consumption might reduce the risk of colon and
rectal cancers.