Circulating insulin-like growth factor-1 is positively associated with growth and cognition in 6- to 9-year-old schoolchildren from Ghana

Abstract

There is increasing evidence that dairy milk positively affects linear growth, weight and body composition in children, particularly in low- and middle-income countries (1)(2). This effect of milk on growth has been proposed to be mediated by IGF-I (2), (3). The aim of this double-blinded, controlled trial was to evaluate the effect of milk supplements on circulating IGF-I and to assess IGF-I as a correlate of growth and cognition in children. The study enrolled 261 healthy children (median age 6–9 years) from 13 schools in Ghana. They were divided into 3 groups on the basis of milk intake (Milk8 = 8.8 g milk protein; Milk/Rice = 4.4 g milk + 4.4 g rice protein; Milk4 = 4.4 g milk protein) and control children who received a powder containing multiple micronutrients. Auxology, body composition (assessed by bioelectric impedance analysis), IGF-I and free amino acids (analyzed by dried blood spots at 3.5 and 8.5 months) and cognitive function (Cambridge Neuropsychological Test Automated Battery-CANTAB) were measured. Only Milk8 group showed a statistically significant increase in IGF-I compared to control subjects (+15.3; 95% CI: 9.4, 31.2). During the intervention, IGF-I increased more in girls than in boys. The change in IGF-I levels was positively associated with changes in amino acids (valine, leucine, Amino-butyric acid, Threonine, Trytophan), height, weight, fat free mass and 4 of 5 CANTAB domains.