Sex Differences in the Relationship Between Nutrient Intake and Mortality Results of the Shika Cohort Study

Background/Objectives: Macronutrients (protein, fat, and carbohydrate) provide sources of energy and play crucial roles in various physiological functions. However, sex differences in the relationships between protein, fat, and carbohydrate intakes and all-cause mortality remain unclear. The present study investigated sex differences in the relationships between protein, fat, and carbohydrate intakes and all-cause mortality using longitudinal epidemiological data. Methods: A total of 3743 healthy residents (1666 men and 2077 women) aged 40 years or older were followed up (men: 6.64 ± 1.51 years, women: 6.76 ± 1.28 years from 2013) in Shika Town, Ishikawa Prefecture, Japan. Nutrient intake was assessed at the baseline survey using the Brief Self-Administered Dietary History Questionnaire. The prospective relationship between baseline nutrient intake and all-cause mortality during the follow-up period, stratified by sex, was evaluated using two-way analysis of covariance and multiple logistic regression analysis, adjusted for age and BMI. Results: We documented 330 deaths (179 men and 151 women) during the 10-year follow-up period. Significant interactions between death and sex were observed for the intake of total protein (p < 0.001), animal protein (p < 0.001), vegetable protein (p = 0.033), total fat (p = 0.012), and animal fat (p = 0.024). Multiple logistic regression analysis demonstrated that total protein (p = 0.004), and animal protein (p = 0.010) decreased the all-cause mortality and increased carbohydrates (p = 0.046) in women. In men, total fat (p = 0.017) decreased the all-cause mortality. Conclusions: The present study revealed distinct sex differences in the effects of total protein, animal protein, and carbohydrate intakes on all-cause mortality. This sex difference may be due to the sex differences in nutrients intake themselves.