Optimized protein intakes in term infants support physiological growth and promote long-term health.

Breastfeeding is associated with a reduced later obesity risk, relative to feeding convention infant formula. Breastfeeding induces less weight gain during the first two years of life, which predicts less obesity up to adulthood. We tested the hypothesis that a high infant protein supply promotes weight gain and obesity risk, mediated by increased plasma amino acids and growth factors, insulin and insulin like growth factor 1 (IGF-1). A large multi-centre double blind trial randomized formula-fed infants to conventional bottle milk with a high protein content, or an intervention formula with a reduced protein content more similar to levels provided with human milk. Protein-reduced formula normalized weight, body mass index and body fatness up to 6 years, relative to a breastfed reference group, and reduced the adjusted odds for obesity 2.6-fold. Available data indicate potential underlying mechanisms. We conclude that infant feeding has very marked long-term programming effects on later BMI, obesity and adiposity, with major public health implications. Breastfeeding lowers the risk for later obesity and adiposity. This provides additional motivation for proactively and enthusiastically promoting, protecting and supporting breastfeeding. A high milk protein intake in infancy increases the long-term risk for obesity and adiposity. Infants not or not fully breastfed should receive infant formula delivering protein in amounts more similar to human milk contents, with high protein quality. Other sources of very high infant protein intakes, particular drinking unmodified cows' milk, should be avoided in infancy.