Association between Japanese diet and the risk of cancer incidence: data from the Ohsaki Cohort Study

The effect of the Japanese diet on cancer incidence remains unclear. The purpose of this study was to examine the association between the Japanese diet and the risk of all-cause and site-specific cancer. We analysed 14-year follow-up data from the Osaki Cohort study of 25 570 Japanese men and women aged 40–79 years. The Japanese diet was evaluated using a thirty-nine-item FFQ at baseline. Based on a previous study, we used eight food items to calculate the Japanese Diet Index score: rice, miso soup, seaweed, pickles, green and yellow vegetables, seafood, green tea and beef and pork. The participants were divided into quartiles based on their Japanese Diet Index scores. The Cox proportional hazards model was used to estimate the hazard ratios and 95 % CI of cancer incidence. During the mean 10·4 years of follow-up, we identified 3161 incident cases of all-cause cancer. Multivariable analysis showed that the Japanese Diet Index score was not associated with cancer incidence. In comparison with Q1 (the lowest), the multivariable hazard ratios and 95 % CI were 1·01 (0·92, 1·12) for Q2, 0·94 (0·85, 1·04) for Q3 and 1·06 (0·95, 1·18) for Q4 (the highest). Furthermore, separate analyses of nine common cancer sites demonstrated no association with the Japanese Diet Index score. The results were consistent even after a sensitivity analysis using multiple imputation. This prospective study showed that the Japanese diet was not associated with cancer incidence. The results suggest that the Japanese diet could contribute to a person’s overall health and well-being without increasing cancer risk.