Branched chain amino acids and body composition in healthy, non-obese women

Background Branched chain amino acids (BCAAs, Valine, Leucine, and Isoleucine) are indispensable for skeletal muscle metabolism. However, the association between BCAA and body composition (lean and fat mass) have been seldom studied. Aims To assess the associations between BCAA levels and body composition as assessed by Dual Energy X-ray Absorption (DEXA) in a sample of healthy, non-obese women. Methods Cross-sectional study using data from the OsteoLaus study in our city. Whole body, gynoid, android and appendicular lean and fat mass and percentages were assessed. Results Data from 388 women (mean age 58.4±6.4 years, BMI 23.4±2.9 kg/m2) were analysed. After multivariable analysis, the strongest associations were found for all BCAAs with the android %fat/gynoid %fat ratio (beta coefficient=0.263, 0.228 and 0.219 for Valine, Leucine and Isoleucine, respectively) and the trunk fat mass/limb fat mass ratio (beta coefficient=0.257, 0.254 and 0.249 for Valine, Leucine and Isoleucine, respectively), and between Valine with android fat mass and visceral fat mass (table). Stepwise linear regression identified the android %fat/gynoid %fat ratio as the body composition marker most associated with valine levels, and the trunk fat mass/limb fat mass ratio as the body composition marker most associated with leucine and isoleucine. Conclusion In healthy middle-age woman, blood BCAAs levels were mainly associated with fat mass and not with lean mass, suggesting that BCAAs might be more related to fat than to muscle metabolism.