Dietary acid load and mortality:  Results from the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study

Purpose: The impact of diet on the body acid-base balance may be related to the risk of various chronic diseases. This prospective cohort study examined the relationships between the dietary acid load and all-cause and cause-specific mortalities in a large Japanese population. Methods: The data of 74,360 subjects (aged 35-69 years in the baseline survey) in the Japan Multi-Institutional Collaborative Cohort Study were analyzed. The dietary acid load was estimated using the net endogenous acid production (NEAP) score. Cox proportional hazards regression analyses were performed to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortalities according to the quartiles of the energy-adjusted NEAP score after adjustments for potential confounders. Results: During a mean follow-up of 11.6 years, 3,761 deaths were identified. A higher NEAP score was associated with higher all-cause (HR 1.16, 95% CI 1.04-1.28) and cerebrovascular disease mortality (HR 1.69, 95% CI 1.08-2.65). Sex-stratified analyses showed that the NEAP score was associated with all-cause and cause-specific mortalities, including cerebrovascular disease mortality in male subjects, but not in female subjects. Conclusion: This study suggest that the dietary acid load is associated with all-cause and cause-specific mortalities, including cerebrovascular disease mortality, in Japanese male adults.