The relationship between bioactive components in breast milk and bone mass in infants.

Human breast milk (HBM) contains numerous bioactive components, recently shown to be associated with growth and body composition in breastfed offspring. Reciprocity in adipogenic and osteogenic pathways suggests bone mass may also be influenced by these components. The association between bioactive components found in HBM and bone mineral content (BMC), to our knowledge, is unknown. The purpose of this proof-of-principle study was to evaluate the association between specific bioactive components in HBM in exclusively breastfed infants and skeletal health in the first 6 months of life and examine potential gender differences in these associations. Thirty-five mother-infant dyads were followed from 1 to 6 months. The contents of a single breast expression were used for analyses of bioactive components (insulin, glucose, leptin, interleukin-6 and tumor necrosis factor-α (TNFα), whereas BMC was evaluated by dual-energy X-ray absorptiometry. In the total sample, there was a positive association between TNFα and BMC at 1 (P=0.004) and 6 months (P=0.007). When stratified by sex, females exhibited a positive association between BMC and glucose and an inverse relationship between BMC and TNF-α at 1 month with TNF-α strengthening (P=0.006) at 6 months. In males, at 6 months a positive relationship between BMC and HBM glucose and an inverse relationship with HBM leptin were observed with no associations observed at 1 month. Although preliminary, the associations between bioactive components in HBM highlight the importance HBM has on bone accretion. It is critically important to identify factors in HBM that contribute to optimal bone health.