Body fat and bone mineral content of infants fed breast milk, cow's milk formula, or soy formula during the first year of life.

OBJECTIVE: To characterize growth, fat mass (FM), fat-free mass (FFM), and bone mineral content (BMC) longitudinally in healthy infants fed breast milk (BM), cow's milk formula (CMF), or soy formula (SF) during the first year of life. STUDY DESIGN: Infants were assessed at age 3, 6, 9, and 12 months. Growth was evaluated using standard anthropometric techniques, and body composition was assessed by dual-energy X-ray absorptiometry. Mixed-effects models with repeated measures were used, adjusting for race, socioeconomic status, gestational age, birth weight, birth length, sex, age, and diet history. RESULTS: Compared with infants fed formulas, infants fed BM had higher FM at age 3 months, and lower FFM at age 6-12 months (P < .001). Infants fed SF had greater FFM at age 6 months and 9 months compared with infants fed CMF (P < .001). BMC was higher in infants fed BM and lower in infants fed SF at age 3 months (P < .001), but by age 12 months, BMC was significantly higher in infants fed SF. CONCLUSION: Infants fed CMF and SF had significantly different fat and bone accretion trajectories, and all infants fed formula were significantly different from infants fed BM. Infants fed SF had a leaner body phenotype throughout the first year of life, lower bone mineralization by age 3 months, and greater bone mineral accretion during the first year of life compared with infants fed BM or CMF. Although the body composition profiles are strikingly different in these 3 diet groups, the implications for long-term health outcomes and bone health remain unclear.

Ultrasonographic patterns of reproductive organs in infants fed soy formula: comparisons to infants fed breast milk and milk formula.

OBJECTIVE: To determine if differences exist in hormone-sensitive organ size between infants who were fed soy formula (SF), milk formula (MF), or breast milk (BF). STUDY DESIGN: Breast buds, uterus, ovaries, prostate, and testicular volumes were assessed by ultrasonography in 40 BF, 41 MF, and 39 SF infants at age 4 months. RESULTS: There were no significant feeding group effects in anthropometric or body composition. Among girls, there were no feeding group differences in breast bud or uterine volume. MF infants had greater (P < .05) mean ovarian volume and greater (P < .01) numbers of ovarian cysts per ovary than did BF infants. Among boys, there were no feeding group differences in prostate or breast bud volumes. Mean testicular volume did not differ between SF and MF boys, but both formula-fed groups had lower volumes than BF infants. CONCLUSIONS: Our data do not support major diet-related differences in reproductive organ size as measured by ultrasound in infants at age 4 months, although there is some evidence that ovarian development may be advanced in MF-fed infants and that testicular development may be slower in both MF and SF infants as compared with BF. There was no evidence that feeding SF exerts any estrogenic effects on reproductive organs studied.