Breast milk folic acid and zinc concentrations of lactating, low socio-economic, Amazonian women and the effect of age and parity on the same two nutrients

Abstract

The levels of folic acid and zinc in breast milk of about 25 women in their first trimester of lactation from each of eight towns in the Brazilian Amazon basin were determined. In order to compare the effects of age and parity on the breast milk folate and zinc levels, the results were analysed together. Thirty-one (60 per cent) of the women in their first month of lactation and 35 (51.5 per cent) in their second month had milk total folate levels below the calculated lower limit of adequacy; only 21 (47 per cent) of the women in their third month of lactation had milk total folate concentrations below the same limit. The breast milk zinc levels, however, were worse, with 35 (95 per cent) and 61 (97 per cent) of the women in their first and second months of lactation and all the women in their third month of lactation having values below the calculated lower limit of adequacy. Both in the case of total folate and zinc, the calculated lower limits of adequacy were obtained from the respective Recommended Dietary Allowances (RDAs) of a 0-6 month old infant and the average milk production of lactating women. While the mean breast milk folate levels (both total and free) showed no significant changes during the months of lactation, the average milk zinc levels showed a significant decrease between the first and second and first and third months of lactation. The age of the women did not significantly influence either the breast milk folate or zinc levels. However, the milk folate concentrations showed a significant decrease (P < 0.05) amongst the multigravidae compared with the primigravidae. The breast milk zinc levels, on the other hand, were not influenced by the parity of the women.