RESUMO
BACKGROUND: Preterm newborns have low vitamin A reserves at birth, which increases their risk of morbidity and mortality. In the absence of supplementation, breast milk is the only source of this nutrient for exclusively breastfed infants. AIMS: To assess retinol concentration in preterm milk and the relationship between this retinol concentration and lactation phase, degree of prematurity, and maternal serum retinol level. STUDY DESIGN: Longitudinal study. SUBJECTS: Fifty-eight preterm mothers. OUTCOME MEASURES: Colostrum (1-3d), transitional (7-15d), and mature human milk (30-55d) samples were collected. Maternal blood was collected once at postpartum. Retinol level was measured using high-performance liquid chromatography. RESULTS: Milk retinol concentration was statistically different between lactation phases (p<0.001): 2.84±1.05µmol/L in colostrum (58), 3.47±1.28µmol/L in transitional (58), and 2.03±0.61µmol/L in mature milk (30). No difference was found in milk retinol levels between groups with different degrees of prematurity (p>0.05). Maternal serum retinol (1.82±0.50µmol/L) did not correlate with milk levels (p>0.05). CONCLUSIONS: Retinol level in preterm milk seems to be independent of the degree of prematurity and maternal serum status. A significant increase in micronutrient levels in transitional milk was observed, which is likely to contribute to reserves in the premature liver.