Effect of environment on growth: auxological and hormonal parameters in African and Italian children

Genetic factors are the most important determinant of final height in developed countries, while in underprivileged countries food intake is crucial. Nutrients, in turn, may importantly affect IGF-IGFBP system which is a critical regulator of growth. The aim of this study was to evaluate the influence of nutrition on IGF system components, as well as on growth by comparing these variables in two selected populations of children living either in poor or in privileged environmental conditions.

Height and weight were recorded in 38 normal African children, living in a Catholique Mission in Ivory Coast, and in 93 normal Italian children. IGF-I, IGF-II, IGFBP-3 and ALS were evaluated in all subjects.

A normal height in spite of markedly reduced IGF-I, IGFBP-3, ALS and BMI was observed in African children, while the ratio IGF-I/IGFBP-3 was comparable in the two populations. IGF-II was slightly but significantly higher in Africans than in Italians.

In Africans a suboptimal nutritional condition may produce a dramatic reduction of IGF-I, ALS and IGFBP-3, although the final height results minimally affected. This suggests that only a small fraction of the circulating IGF-I is sufficient for growth and confirms what has been reported on liver IGF-I-deficient and ALS knock-out mice. The secular statural trend observed in developed countries is probably due to the increase of IGF-I consequent to the improved nutritional conditions.