Background: Although the short-term benefits of mineral supplementation in preterm infants has been established, the long-term benefits are less clear. The purpose of the study was to evaluate effects of early-life mineral, vitamin D, and breast milk intake on bone mineral status in children 9 to 11 years of age who were born prematurely.
Methods: Seventy preterm infants born 1985 through 1987 were randomized into four groups: to receive a vitamin D dose of 500 or 1000 IU/day and calcium- and phosphorus-supplemented or unsupplemented breast milk. At 3 months of age, radial bone mineral content was determined by single-photon absorptiometry and vitamin D metabolites were assessed. At 9 to 11 years of age, the bone mineral status of the radius and lumbar spine was assessed using dual energy x-ray absorptiometry.
Results: At the age of 3 months, the preterm infants with diets supplemented with minerals had 36% higher bone mineral content than the preterm infants whose diet was not supplemented with minerals. At the age of 9 to 11 years, in contrast, bone mineral status was comparable among the groups, irrespective of different mineral supplementation during the neonatal period. Interestingly, the lumbar bone mineral apparent density was positively related to lactation in mineral-supplemented children. There was neither short-term nor long-term benefit to bone mineral status of a vitamin D dose of 1000 IU/day compared with 500 IU/day.
Conclusions: The short-term benefit to bone mineral density in preterm infants of mineral supplementation of the early diet is obvious, but, in the long term, the effects seem to disappear. The results also imply that a relatively long period of breast-feeding may be needed to optimize long-term bone mineral acquisition in the lumbar spine.