Longitudinal Association Between Sodium and Potassium Intake and Physical Performance in Older Adults.

Background: Aging is associated with a progressive difficulty to maintain ion regulation, which might impair the capacity for muscle contraction. Thus, the aim of this study was to examine the association between 5-year changes in dietary intake of sodium and potassium and changes in physical performance among older adults.
Methods: We performed a prospective study with 868 participants from the Seniors-ENRICA cohort. Diet was measured with a validated diet history and physical performance was measured with the Short Physical Performance Battery (SPPB), both in 2012 and 2017. Analyses were performed with linear regression models adjusted for sociodemographic variables, lifestyle, and morbidity, using changes in the intake of sodium and potassium and changes in the sodium/potassium ratio during follow-up as independent variables, and the continuous change in the SPPB score as the dependent variable.
Results: Over 5 years of follow-up, a 1 SD increase in sodium intake (ie, 0.73 g/d) was associated with a 0.13 (95% confidence interval [CI]: 0.26-0.01) points reduction in the SPPB score, while a 1 SD increase in potassium intake (ie, 0.70 g/d) was associated with a 0.19 (0.05-0.34) points increment in the score. In addition, a 1 SD increase in the sodium-to-potassium ratio (ie, 0.30) was associated with worse SPPB (-0.58 [-0.95 to -0.21]). Participants who adhered to dietary recommendations for minerals at baseline but became noncompliant during follow-up decreased their result in the SPPB.
Conclusion: An increase of dietary sodium intake, a decrease of potassium intake and the resulting increment in the sodium-to-potassium ratio were prospectively associated with worse physical performance in older adults.
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