Stunting is widespread in low-income settings due to inferior quality diets and infections, which down-regulate serum concentration of insulin-like growth factor-1 (serum IGF-1). Associations between plasma concentrations of amino acids (plasma AA), serum IGF-1 and growth remain underexplored in humans. To assess the role of plasma AA as correlates of serum IGF-1, linear growth and fat-free mass (FFM) among stunted children. In a cross-sectional study nested in a nutrition intervention trial among 750 Ugandan children, aged 12-59 months, with stunting, we assessed anthropometry, recent intake of animal-source foods (ASF), fasting time and body composition. Serum IGF-1, serum concentrations of the inflammatory markers C-reactive protein and α 1 -acid glycoprotein and 21 plasma AA were measured. Mean (SD) age and height-for-age z-score (HAZ) were 32.0 (11.7) months and -3.02 (0.74). Plasma AA data were available for 711-730 (95-97%) children. For 18 AA plasma concentrations were lower among children with elevated inflammatory markers. ASF intake within 24 hours was associated with few AA; meat intake was associated with higher plasma methionine, while cow’s milk and egg intake were not associated with plasma concentration of any EAA. Nearly all plasma AA, including all EAA, were positively associated with serum IGF-1, after adjusting for fasting and markers of inflammation. Only a few plasma AA, including methionine, threonine, and valine, were associated with FFM or FFM index. Only plasma tyrosine and taurine were associated with HAZ. Among stunted children most plasma AA were positive correlates of serum IGF-1 but few correlated with HAZ or FFM. Further research is needed to clarify the role of plasma AA in the complex mechanisms underlying growth faltering in malnourished children.
Larnkjær et al. (Wed,) studied this question.