Dietary Carbohydrate and Fat Intakes and Risk of Mortality in the Japanese Population: the Japan Multi-Institutional Collaborative Cohort Study

Background: Previous cohort studies have yielded contradictory findings regarding the associations of dietary carbohydrate and fat intakes with risks of mortality. Objectives: We examined long-term associations of carbohydrate and fat intakes with mortality.Methods: In this cohort study, 34,893 men and 46,440 women aged 35-69 y (mean body mass index of 23.7 and 22.2 kg/m2, respectively) were followed up from the baseline survey (2004-2014) to the end of 2017 or 2018. Intakes of carbohydrate, fat, and total energy were estimated using a food frequency questionnaire. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated for all-cause and cause-specific mortality according to percentage of energy intakes of carbohydrate and fat.Results: During a mean 8.9-y follow-up, we identified 2783 deaths (1838 men and 945 women). Compared with men who consumed 50% to <55% of energy from carbohydrate, those who consumed <40% carbohydrate energy experienced a significantly higher risk of all-cause mortality (the multivariable-adjusted HR: 1.59; 95% CI: 1.19-2.12; P-trend = 0.002). Among women with 5 y or longer of follow-up, women with high -carbohydrate intake recorded a higher risk of all-cause mortality; the multivariable-adjusted HR (95% CI) was 1.71 (0.93-3.13) for = 65% of energy from carbohydrate compared with that for 50% to <55% (P-trend = 0.005). Men with high fat intake had a higher risk of cancer-related mortality; the multivariable-adjusted HR (95% CI) for = 35% was 1.79 (1.11-2.90) compared with that for 20% to <25%. Fat intake was marginally inversely associated with risk of all-cause and cancer-related mortality in women (P-trend = 0.054 and 0.058, respectively).Conclusions: An unfavorable association with mortality is observed for low-carbohydrate intake in men and for high-carbohydrate intake in women. High fat intake can be associated with a lower mortality risk in women among Japanese adults with a relatively high-carbohydrate intake.

Automated summary

This study aimed to examine the associations between carbohydrate and fat intakes and mortality risk. The results showed that low carbohydrate intake was associated with increased all-cause mortality risk in men, while high carbohydrate intake was associated with increased all-cause mortality risk in women. Additionally, high fat intake was potentially associated with lower mortality risk in women with relatively high carbohydrate intake.