Early life nutrition and bone development in children.

Fetal and early life may be a critical period for the development and/or programming of metabolic systems, including the skeleton. There are increasing human data from cohort studies on the association between early life nutrition and bone development in children. Breastfed children initially have lower bone mass than bottle-fed children, but longer-term studies suggest that they have higher bone mass (size adjusted) by age 8 years, especially in children born at term. By the time of peak bone mass, both preterm and term children have higher bone mass indicating a different bone accrual trajectory curve. These children also have lower fracture risk. Diet in utero has also been associated with subsequent bone mass from ages 6 to 16 years (but not fracture). Positive associations include milk, phosphorus, magnesium, potassium, protein, folate, calcium and vitamin D, while fat intake is negative. Smoking also interferes with bone mineralization possibly due to impaired placental function, but this deleterious effect on bone mass appears to diminish over time. All of these associations are statistically significant and independent of important confounders and later environmental exposures, suggesting that osteoporosis prevention programs need to start very early in the life cycle.