Abstract

Circulating amino acids are potential markers of body composition. Previous studies are mainly limited to middle age and focus on either fat or lean mass, thereby ignoring overall body composition. We investigated the associations of fat and lean body mass with circulating amino acids in older men and women. We studied 594 women and 476 men from the Helsinki Birth Cohort Study (age 62–74 years). Bioelectrical impedance analysis was used to indicate two main body compartments by fat (fat mass/height²) and lean mass indices (lean mass/height²), dichotomized based on sex-specific medians. Eight serum amino acids were quantified using nuclear magnetic resonance spectroscopy. General linear models were adjusted for age, smoking, and fasting glucose. Higher lean mass index (LMI) was associated with higher concentrations of branched-chain amino acids in both sexes (p ≤ .001). In men, LMI was also positively associated with tyrosine (p = .006) and inversely with glycine (p < .001). Higher fat mass index was associated with higher concentrations of all branched-chain amino acids, aromatic amino acids (phenylalanine and tyrosine), and alanine in both sexes (p ≤ .008). Associations between body composition and amino acids are largely similar in older men and women. The associations are largely similar to those previously observed in younger adults.