Estado Nutricional em vitaminas e de mães e crianças pré-termo e termo do nascimento aos 3 meses pós-parto

Abstract

Vitamin E is a fat-soluble antioxidant micronutrient extremely important for preterm newborns (< 37 weeks gestation) since it protects the central nervous system and prevents hemolytic anemia and bronchopulmonary dysplasia. Due to its limited placental transfer, the provision of vitamin E to the infant through breast milk is essential to ensure an adequate supply and to prevent/correct deficiencies. There is limited data on the vitamin E recovery in infants through the lactation period and the composition of alpha-tocopherol in preterm breast milk. This study aimed to evaluate the differences in the vitamin E nutritional status of women, preterm and term infants from birth to 3 months postnatal, their relationships and the concentration of alpha-tocopherol in breast milk. A prospective study was initially conducted with 235 postpartum women and infants attending two public maternities in Rio Grande do Norte, Brazil, 124 allocated in the preterm group and 111 in the term group (≥ 37 weeks), being followed up until 90 days after delivery. Colostrum, maternal blood and umbilical cord were collected up to 48 hours after delivery. Breast milk and dietary data were collected at 7, 30 and 90 days postpartum, as well as maternal and children’s blood at day 90. Alpha-tocopherol was analyzed by High Performance Liquid Chromatography. Vitamin E dietary intake of women and the vitamin supply to the infant were assessed according to consumption recommendations for the age group. The concentration of maternal serum alphatocopherol was not different between the groups, and an increase in vitamin E deficiency was found (< 517 µg/dL) through lactation (from 8.6% to 22.2%), reaching 789.6 (313.1) µg/dL in the preterm group and 875.3 (341.6) µg/dL in the term group (p = 0.197). All women presented inadequate vitamin E intake during lactation (<16mg/day). Over 90% of infants presented low alpha-tocopherol levels at birth (<500µg/dL), and at day 90 the mean concentration of serum alpha-tocoferol was 583.3 (209.4) µg/dL in the preterm group and 884.4 (458.8) µg/dL in the term group (p < 0.007), evidencing higher percentages of inadequacy in the infants from the preterm group. There was a positive association in serum alpha-tocopherol levels between the mother and the infant, and the premature delivery negatively influenced the infant's serum levels. In the preterm group, alpha-tocopherol levels were lower in colostrum, yet higher in transitional and mature milk (day 30), in comparison to the term group (p < 0.0001). Only mature milk did not provide the vitamin E amount recommended for infants (4 mg/day). Thus, it was found a high inadequacy of vitamin E at 3 months postpartum in both women and preterm children, differences in preterm milk composition and a possible supply of small amounts of vitamin E by mature milk, highlighting the need of greater nutritional assistance during lactation, especially due to vitamin E deficiency and its effects on children's cognitive development.