Effect of Obesity and Exercise Training on Plasma Amino Acids and Amino Metabolites in American Indian Adolescents

Context: Amino acids (AAs) and their metabolites are altered with obesity and may be predictive of future diabetes in adults, but there are fewer studies on AAs, as well as conflicting findings on how they vary with obesity, in adolescents. Objective: To determine whether plasma AAs vary with body composition and insulin sensitivity and are altered in response to exercise training. Design: Cross-sectional, and an exercise intervention. Setting: Tribal wellness center. Participants: American Indian boys and girls, 11 to 17 years of age with obesity (Ob, n = 58) or normal weight (NW, n = 36). Intervention: The Ob group completed 16 weeks of aerobic exercise training. Main Outcome Measure: A panel of 42 plasma AAs. Results: Compared with the NW group, the Ob group had lower aerobic fitness and insulin sensitivity (interactive homeostasis model assessment 2), 17 AAs that were higher, and 7 AAs that were lower. Branched-chain AAs (+10% to 16%), aromatic AAs (+15% to 32%), and glutamate were among the higher AAs; all were positively correlated with body fat and negatively correlated with insulin sensitivity. The lysine metabolite 2-aminoadipic acid (2-AAA) and the valine metabolite beta-aminoisobutyric acid (BAIBA) were 47% higher and 29% lower, respectively, in the Ob group, and were positively (2-AAA) and negatively (BAIBA) correlated with insulin sensitivity. Exercise training increased aerobic fitness by 10%, but body composition, insulin sensitivity, and AAs were not significantly changed. Conclusions: Several plasma AAs are altered in American Indian adolescents with obesity and are associated with insulin sensitivity, but they were not altered with this exercise intervention.