Early Influences of Nutrition on Postnatal Growth

Health and nutrition modulate postnatal growth. The availability
ofamino acids and energy, and insulin and insulin-like growth
factor-I(IGF-I) regulates early growth through the mTOR pathway.
Amino acids andglucose also stimulate the secretion of IGF-I and
insulin. Postnatalgrowth induces lasting, programming effects on
later body size andadiposity in animals and in human observational
studies. Rapid weightgain in infancy and the first 2 years was
shown to predict increasedobesity risk in childhood and adulthood.
Breastfeeding leads to lesserhigh weight gain in infancy and
reduces obesity risk in later life byabout 20%, presumably partly
due to the lower protein supply with humanmilk than conventional
infant formula. In a large randomized clinicaltrial, we tested the
hypothesis that reduced infant formula proteincontents lower
insulin-releasing amino acid concentrations and therebydecrease
circulating insulin and IGF-I levels, resulting in lesser
earlyweight gain and reduced later obesity risk (the ‘Early
ProteinHypothesis’). The results demonstrate that lowered protein
in infantformula induces similar - but not equal - metabolic and
endocrineresponses and normalizes weight and BMI relative to
breastfed controlsat the age of 2 years. The results available
should lead to enhancedefforts to actively promote, protect and
support breastfeeding. Forinfants that are not breastfed or not
fully breastfed, the use of infantformulas with lower protein
contents but high protein quality appearspreferable. Cows’ milk as
a drink provides high protein intake andshould be avoided in
infancy.