MINERAL BALANCE AND WHOLE-BODY BONE-MINERAL CONTENT IN VERY-LOW-BIRTH-WEIGHT INFANTS

Fat and mineral metabolic balance studies were performed in 25 normal very low-birth-weight infants (less than or equal to 1500 g at birth) fed either pooled pasteurized human milk supplemented with calcium, ph osphorus and magnesium, or a preterm formula. Calcium, phosphorus and magnesium intake were similar in both groups and averaged 100 mg/kg/da y, 72 mg/kg/day and 8 mg/kg/day, respectively. Calcium and phosphorus retention was higher in the subjects fed fortified human milk than in those receiving a preterm formula (65+/-14 and 62+/-9 mg/kg/day versus 55+/-12 and 47+/-7 mg/kg/day respectively). The difference was only s ignificant for phosphorus. Magnesium retention was similar in the two groups and averaged 3 mg/kg/day. Fat intake and absorption was signifi cantly higher in the preterm formula fed group than in the one fed for tified human milk (5.5+/-0.4 g/kg/day and 88+/-4% versus 4.2+/-1 g/kg/ day, 79+/-6% respectively). Assessment of the whole body bone mineral content by dual energy X-ray absorptiometry was performed at 3 and 6 m onths of age in another group of 25 low-birth-weight infants fed eithe r fortified human milk or a preterm formula. Whole body bone mineral c ontent (BMCt) was low (43.3+/-30.8 g of hydroxyapatite) at 3 months of age (theoretical term) compared to normal full-term newborns at birth . There was no significant influence of the diet. At 6 months of age, BMCt reached 168.6+/-36.6 g, a value similar to that of full-term newb orns, with no significant difference between the two regimen groups. T he deficit in the 12 subjects who had a BMCt under 30 g at 3 months of age had been corrected at age 6 months. Premature babies fed a pooled pasteurized human milk enriched with calcium, phosphorus and magnesiu m favored a better retention of calcium and phosphorus. However, no si gnificant influence of the two diets studied was observed on the gain in BMCt over the first 6 months of life.