High Dietary Acid Load Score Is Associated with Increased Risk of Type 2 Diabetes in Japanese Men: The Japan Public Health Center-based Prospective Study

Background: Diet-induced metabolic acidosis has been linked to cardiometabolic abnormalities in Westerners, but the evidence on this issue is scarce in Asians. Objective: The present study prospectively examined the association between dietary acid load and type 2 diabetes (T2D) in Japanese adults. Methods: Study participants were 27,809 men and 36,851 women, aged 45-75 y, who completed a dietary questionnaire of the second survey of the Japan Public Health Center based Prospective Study and had no previous history of T2D. Dietary intake was assessed by using a validated 147-item food-frequency questionnaire. Potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores were derived from the nutrient intake. A multilevel logistic regression model was used to estimate ORs and 95% Cis of self-reported, physician-diagnosed T2D over 5 y, with adjustment for potential confounding variables. Results: A total of 1191 cases of newly diagnosed T2D were reported. PRAL score was positively associated with T2D in men; the multivariable-adjusted ORs (95% CIs) for the lowest through the highest quartiles of PRAL were 1.00, 1.09 (0.87, 1.36), 1.10 (0.88, 1.37), and 1.25 (1.01, 1.55) (P-trend = 0.047). Further adjustment for dietary intake strengthened the association. NEAP score was not associated with the risk of T2D (P-trend = 0.20). In stratified analyses, the positive association between PRAL and T2D was confined to younger men (age <50 y; P-trend = 0.046). There was no association between dietary acid load score and T2D in women. Conclusion: A high dietary acid load score is associated with an increased risk of T2D in Japanese men.