Infant feeding mode affects early growth and body composition

Background. Differences in the growth pattern of breastfed (BF) and formula -fed (FF) infants are well-recognized and have been attributed to differenc es in nutrient intake. However, the impact of qualitative and quantitative differences in nutrient intake on the body composition of BF and FF infants has been unclear. Furthermore, it is unknown whether putative differences in body composition persist beyond weaning. Design. Prospective cohort study. Methods. Repeated anthropometric and body composition measurements were per formed on 40 BF and 36 FF infants at 0.5, 3, 6, 9, 12, 18, and 24 months of age. A multicomponent body composition model based on total body water by deuterium dilution, total body potassium by whole body counting, and bone m ineral content by dual-energy x-ray absorptiometry was used to estimate fat -free mass (FFM) and fat mass (FM). Independent measurements of FFM and FM were made using total body electrical conductivity and dual-energy x-ray ab sorptiometry. By design, infants were either exclusively BF or FF from birt h to 4 months of age; thereafter, the feeding mode was at the discretion of the parents. Infant food intake was measured at 3, 6, 12, and 24 months of age using 3-day weighed-intake records. Data were analyzed by repeated mea sures analysis of variance. Results. Weight velocity was higher in FF than BF infants age 3 to 6 months , and higher in FF than BF girls 6 to 9 months of age. Adjusted for gender and baseline values, BF infants had lower total body water at 3 months, low er total body potassium at 3 to 24 months, and lower bone mineral content a t 12 months. The multicomponent model indicated that FFM was lower in BF th an FF infants at 3 months, and FM and %FM were higher in BF than FF infants at 3 and 6 months (boys only). Total body electric conductivity confirmed lower FFM in BF than FF infants at 3 months, as well as at 6 and 9 months; FM and %FM were higher in BF than FF at 3 and 6 months, and 9 months (boys only). Intakes of energy, protein, fat, and carbohydrate were lower in BF t han FF infants at 3 and 6 months, and were positively correlated with weigh t gain and FFM gain, but not FM gain. No differences in nutrient intakes we re observed at 12 or 24 months. Conclusion. Infant feeding mode is associated with differences in body comp osition in early infancy which do not persist into the second year of life.