Association of whole blood amino acid and acylcarnitine metabolome with anthropometry and IGF1 serum levels in healthy children and adolescents

Background: Physiological changes of blood amino acids and acylcarnitines during healthy child development are not well studied. The LIFE Child study offers a platform with a large cohort of healthy children to investigate these dynamics. We aimed to assess the intra-person variability of these blood metabolites and associations with anthropometric parameters related to excess body fat and IGF1 serum levels. Methods: Concentrations of 23 amino acids, 5 acylcarnitines and free carnitine of 2213 children aged between 3 months and 19 years were analyzed using liquid chromatography/tandem mass spectrometry. Standard deviation score values were used to account for physiological sex- and age-related differences. The stability of metabolites was assessed through the coefficient of determination. Associations with parameters for body composition and IGF1 serum levels were determined by Pearson correlation and linear regression. Results: Our research reveals substantial fluctuations in metabolite concentrations in the same person during childhood and adolescence. Most metabolites had a positive correlation with parameters of body composition with notable influence of sex, pubertal status and weight group specific differences. Glycine exhibited negative associations with parameters of body fat distribution especially in normal weight girls, overweight/obese boys and during puberty. Conclusions: The observed alterations in metabolite concentrations contribute to our knowledge on the complex interplay between blood amino acid and acylcarnitine levels and metabolic health in children and adolescents.