Concentrações de vitamina A no leite humano e características socioeconômicas e nutricionais maternas: resultados de estudos brasileiros

Retinol status and associated factors in mother-newborn pairs

BACKGROUND

Vitamin A deficiency is still considered to be a nutritional problem during pregnancy, lactation and early childhood. The present study aimed to assess the vitamin A status of women and their newborns in the Brazilian Northeast and to determine the association between retinol in the maternal serum, umbilical cord blood and colostrum.

METHODS

Vitamin A status in 65 pairs of women and newborns was assessed from samples of the mother's serum, umbilical cord serum and colostrum using high-performance liquid chromatography. The inadequacy of the vitamin A status of mothers and infants was identified if the retinol values were <0.7 µmol L^- 1 in maternal serum or umbilical cord blood or <1.05 µmol L^-1 in colostrum.

RESULTS

The prevalence of inadequate maternal vitamin A status was 21.5% (95% CI: 11.5%-31.5%) and 13.8% [95% confidence interval (CI) = 5.4%-22.2%] based on maternal serum and colostrum, respectively. Among newborns, 41.5% (95% CI = 29.3%-53.5%) presented a low status of vitamin A based on cord serum. Multiple linear regression analysis identified that maternal serum retinol is a predictor of umbilical cord retinol (P = 0.005). Retinol in maternal serum was lower in mothers who were less educated (P = 0.04) and colostrum retinol was higher in older (P = 0.04) and multiparous (P = 0.002) mothers.

CONCLUSIONS

Vitamin A deficiency is a common problem among mothers attended in public hospitals in Northeast Brazil and maternal retinol concentrations are associated with retinol status in newborns. Maternal age, parity and educational level were related to the maternal vitamin A status.

Efect of vitamin A suplementation: a systematic review

To evaluate the effect of vitamin A supplementation in postpartum infants and women on serum retinol levels and breast milk. The databases Medline, PubMed, Lilacs and SciELO were consulted. The descriptors used were vitamin A, dietary supplement, child, postpartum period, infant and nutrition programs policies. Search found 7432 articles. After elimination of duplicity and application of eligibility criteria, 8 studies remained. All evaluated the effect of vitamin A supplementation on immediate postpartum, five studies used retinyl palmitate supplementation, one with retinyl palmitate and two did not specify the form of supplementation. Six studies evaluated colostrum and two included supplementation of children. It was found that supplementation in the puerperium increases the concentrations of serum retinol and breast milk, however, this result was in the short term and was relevant when the previous concentrations of the mother were low. When maternal serum concentrations are adequate, the retinol content in milk does not change, with little relevance for children. Further studies should be performed to evaluate the effect of megadoses supplementation on serum concentrations of children.

Estado nutricional em vitamina A de puérperas adolescentes e adultas assistidas em maternidade pública

RESUMO Objetivo Avaliar o estado nutricional em vitamina A de puérperas adolescentes e adultas em relação à ingestão alimentar, retinol no soro e colostro e o suprimento desta vitamina para o recém-nascido. Métodos Estudo transversal, incluindo 136 puérperas, sendo 68 adolescentes e 68 adultas, atendidas em uma maternidade pública. A ingestão dietética de vitamina A foi estimada por um questionário de frequência do consumo alimentar. Foram coletados sangue e colostro em condição de jejum para análise dos níveis de retinol. As amostras foram analisadas por cromatografia líquida de alta eficiência. A estimativa da ingestão de vitamina A pelo recém-nascido foi calculada pelo volume ingerido de leite e a média da concentração de retinol no colostro materno. Resultados A estimativa de consumo foi 681,2±535 µgRAE/dia, para as adolescentes, e 891,8±831,5 µgRAE/dia, para as adultas (p>0,05). As médias de retinol sérico foram 40,6±9,7 µg/dL, no grupo das adolescentes, e 44,9±10,9 µg/dL, no das adultas (p<0,05). No colostro, as adolescentes apresentaram concentração de retinol de 83,1±26,5 µg/dL e as adultas de 81,8±29,8 µg/dL (p>0,05). O volume médio ingerido pelos lactentes provenientes de puérperas adolescentes foi de 435,1+140,7 µgRAE/dia e de 409,7+150,8 µgRAE/dia pelos recém-nascidos das adultas. Na análise individual, 42,6% (n=29) das adolescentes e 52,9% (n=36) das mães adultas não supriram adequadamente a recomendação diária do lactente. Conclusão As adolescentes apresentaram ingestão inadequada de vitamina A. Ambos os grupos apresentaram percentuais de inadequação no soro e colostro e, consequentemente, no fornecimento da vitamina A aos recém-nascidos.