Water Intake, Dietary Acid Load, and Body Composition in Aging Females

Background/Objectives: Aging is a natural, gradual, and irreversible process associated with disruptions in homeostasis, causing several unfavorable changes, including changes in body composition. Some studies show that higher water intake can be related to a healthier body composition, but studies in older adults are rare. The aim of this study is to assess the relationship between water intake, dietary acid load, and body composition, and also to assess the interrelationship of these two factors with body composition in older women. Methods: This cross-sectional study involved 195 independently living women aged 65–84. Body composition was assessed using fan-beamed dual-energy X-ray absorptiometry (DXA). Potential renal acid load (PRAL) and water intake were evaluated using the 3-day food record method. Results: Higher water intake was associated with significantly lower android (p = 0.004), gynoid (p < 0.001), and total body fat mass (p = 0.005), as well as higher lean body mass (p = 0.021). Among the assessed anthropometric indicators, only for the appendicular lean mass (ALM) was there a significant difference between the “low-PRAL diet” compared to the “high-PRAL diet” (6.2 ± 0.8 vs. 6.0 ± 0.9 kg/m2; p = 0.045). A “low-PRAL diet” was characterized by a significantly lower energy value, lower protein intake, and a higher plant-to-animal protein ratio than a “high-PRAL diet”. Conclusions: A more acidifying diet pattern appeared to have an adverse effect on lean body mass in older women. The ratio of plant to animal protein may be crucial in this relationship.