High dietary acid load increases the risk of disability in women aged 75 years and older: A community-based cohort study

Abstract

Background: Metabolic acidosis caused by acidogenic diets increases muscle catabolism. High acidogenic diets can increase muscle loss in older adults; however, their association with functional outcomes remains unclear.

Objectives: To investigate whether high acidogenic diets increase the incidence of disability.

Design: Longitudinal study.

Setting: Community-based.

Participants: We included 1,704 community-dwelling Japanese individuals aged ≥ 75 years without disabilities at baseline (52.2 % females).

Measurements: Baseline dietary acid load was assessed using potential renal acid load (PRAL) values, which reflect urinary acidity-with higher values indicating more acidogenic diets. The outcome measure was the one-year incidence of disability, defined as needing for long-term care or support based on certification by the Japanese long-term care insurance system. As the effects of PRAL are reportedly sex-specific, separate analyses were conducted for males and females. The participants were categorized into tertiles (T1-T3, with T1 as the reference) based on their PRAL values. Odds ratios (ORs) and 95 % confidence intervals (CIs) for outcome were calculated using multiple logistic regression analysis after adjusting for age, body mass index, living status, smoking status, hypertension, diabetes, dyslipidemia, energy intake, and alcohol intake.

Results: The PRAL ranges in groups T1, T2, and T3 were: -64.51 to 0.21, 0.27 to 11.34, and 11.41 to 61.00, respectively, in males, and -61.22 to -3.84, -3.75 to 5.89, and 5.90 to 38.68, respectively, in females. Disabilities occurred in 44 (5.7 %) males and 71 (8.7 %) females. ORs (95 % CIs) for disability in T2 and T3 were 0.79 (0.35-1.76) and 0.81 (0.37-1.79), respectively, in males and 1.10 (0.57-2.13) and 1.96 (1.06-3.61), respectively, in females.

Conclusions: A high dietary acid load increased the incidence of disability in older females. Therefore, managing an acidogenic diet may help maintain daily living functions in older females. Future studies should investigate whether sex is an effect modifier.

Keywords: Asian; Epidemiology; Feeding behavior; Functional decline; Older adults.