Blood lipid concentrations of docosahexaenoic and arachidonic acids at birth determine their relative postnatal changes in term infants fed breast milk or formula

Background: Factors other than dietary fatty acids could be involved in the variability observed in blood docosahexaenoate (22:6n-3) and arachidonate (20:4n-6) status in formula-fed infants. Objective: We considered the 22:6n-3 and 20:4n-6 status at birth to be one of these factors and studied its influence on post natal changes in term in fants fed 4 different diets. Design: The blood phospholipid composition was determined at birth and on d ay 42 of feeding in 83 term infants fed breast milk, nonsupplemented formul a, or 2 different 22:6n-3-supplemented formulas. Relations between 22:6n-3 and 20:4n-6 status at birth and their relative postnatal changes, calculate d by the difference between status at the end of the feeding period (6 wk o f age) and at birth, were assessed. Results: Postnatal changes in the plasma and erythrocyte phospholipids 22:6 n-3 and 20:4n-6 were negatively related to their respective concentrations at birth (P < 0.01) and the slopes of the regression lines were not signifi cantly affected by the type of mill;ingested. Adjusted mean values for phos pholipid 22:6n-3 in nonsupplemented-formula-fed infants and for 20:4n-6 in formula-fed infants decreased significantly more than they did in the other infant groups (P < 0.02). The status at birth and the type of milk ingeste d explained 33-64% and 7-47%, respectively, of the variability in postnatal changes. Conclusions: The status of 22:6n-3 and 20:4n-6 at birth in term infants is one of the major determinants of postnatal changes in these fatty acids. Th is finding indicates that research is required to characterize environmenta l, genetic, or both factors, which, in addition to maternal diet, could inf luence fatty acid status at birth.