Search

The requirement of calcium and phosphorus to avoid bone diseases such as rickets in infants born prematurely cannot be met by human milk or low solute formula. Formulas can be supplemented with calcium and phosphorus, but excess calcium can lead to problems with the mineralization of bone, absorption of fats, and the metabolism of other minerals, such as magnesium. Absorption and retention of magnesium were examined in two groups of premature infants who were fed a low solute formula supplemented with calcium, phosphorus, and magnesium. The first group of babies were of very low birth weight, weighing less than 1,500 grams (3.3 pounds), and were less than 32 weeks of gestational age. They were fed three-day mineral balances begun at days 10, 20 30 and 40 after birth. The second group of infants were of low birth rate, at 32 to 34 weeks gestational age, and were fed a single three-day balance at day 10. The dietary intake of calcium and phosphorus was found to affect the levels of magnesium retained by the body. When the calcium or phosphorus intakes were low or when magnesium intake was high, the absorption and retention of magnesium was increased. A greater increase of magnesium absorption and retention was seen as the babies grew older. Supplementation with calcium and phosphorus reduced the absorption and retention of magnesium in babies with very low birth weights. However, supplementation with magnesium improved the absorption and retention of magnesium. The intake of magnesium did not affect the calcium balance but caused the retention of phosphorus from day 20 on, in both very low and low birth weight groups. Therefore, magnesium deficits can still occur at recommended levels of magnesium intake (10 mg/kg/day) for babies born with very low birth weight that are given supplements of calcium and phosphorus. However, if babies are given double the dosage (20 mg/kg/day), magnesium is not lost. (Consumer Summary produced by Reliance Medical Information, Inc.)