Circulating Branched Chain Amino Acids are Associated with Body Composition and Physical Function in Older Adults

Identification of mechanisms underlying age‐related alterations in body composition and decreases in physical function will be important for addressing the growing challenge of providing health care to the rapidly expanding aging population. The goal of the current study was to use mass spectrometry‐based metabolic profiling in combination with principal components analysis (PCA) and multivariable‐adjusted linear regression to provide insight into biologic mechanisms that may underlie body composition and physical function in older adults (N=73). Branched chain amino acids (BCAA: leucine, isoleucine, valine) or their related degradation products were negatively associated with total fat mass, positively associated with thigh muscle cross sectional area (CSA) and the fat‐free mass index (total lean mass/height 2 ), but were both positively and negatively associated with mobility (400 meter gait speed; 400‐m). Collectively these data suggest a role for BCAA metabolism in mechanisms related to body composition and physical function in older adults. Future studies aimed at validation of these results in a larger cohort, and, that test the causative role of these associations are of interest.Component Loadings β ± SE p‐valueTotal FatAA Factor 5: Valine, Leucine, Isoleucine 0.80, 0.77, 0.76 ‐1.5 ± 0.4 0.001Muscle CSAAA Factor 2: 4‐methyl‐2‐oxopentanoate, 3‐methyl‐2‐oxovalerate, 3‐methyl‐2‐oxobutyrate 0.87, 0.83, 0.83 6.2 ± 2.0 0.003 AA Factor 5: Valine, Leucine, Isoleucine 0.80, 0.77, 0.76 6.9 ± 1.9 0.0004FFMIAA Factor 5: Valine, Leucine, Isoleucine 0.80, 0.77, 0.76 0.6 ± 0.2 0.0002400‐mAA Factor 4: α‐hydroxyisovalerate, 2‐hydroxy‐3‐methylvalerate, α‐hydroxyisocaproate 0.87, 0.78, 0.78 0.1 ± 0.0 0.02 AA Factor 5: Valine, Leucine, Isoleucine 0.80, 0.77, 0.76 ‐0.0 ± 0.0 0.04