Double-blind, randomized trial of a synthetic triacylglycerol in formula-fed term infants: effects on stool biochemistry, stool characteristics, and bone mineralization

Background: The low sn-2 palmitate content of infant formulas results in fo rmation of fatty acid calcium soaps in the stools and reduced calcium absor ption. Objective: Our objective was to test the hypotheses that increasing the pro portion of sn-2 palmitate in formula for term infants would result in great er skeletal mineral deposition and reduced stool hardness. Design: Healthy term neonates were randomly assigned to receive standard fo rmula (n = 103) or formula containing 50% sn-2 palmitate (high-sn-2 formula ; n = 100) for 12 wk. One hundred twenty breast-fed infants were also studi ed. The main outcome measures were 1) radial (single-photon absorptiometry) and whole-body (dual-energy X-ray absorptiometry) bone mineral content (WB BMC) at 12 wk and 2) stool frequency, volume, and consistency at 6 and 12 w k. Secondary outcome measures included stool fatty acid content. Results: Infants receiving high-sit-a formula had higher WBBMC (128.1 +/- 9 .7 compared with 122.7 +/- 10.1 g, adjusted for size and sex), softer stool s at 6 and 12 wk, and a lower proportion of stool soap fatty acids than did infants receiving the control formula. Breast-fed infants bad adjusted WBB MC values (128.3 +/- 9.1 g) similar to those of infants fed high-sn-2 formu la and significantly higher than those of infants fed the control formula. Conclusions: Changing the stereoisomeric structure of palmitate in infant f ormula resulted in higher WBBMC, reduced stool soap fatty acids, and softer stools more like those of breast-fed infants. The greater bone mass measur ed could be important if it persists beyond the trial period; this merits f urther investigation.