Postpartum folic acid supplementation of adolescents: impact on maternal folate and zinc status and milk composition.

The objectives of the present study were to assess the impact of lactation on the folate status of adolescents and determine the effect of ingestion of a low-dose postpartum (PP) folic acid supplement on maternal folate and zinc status and milk composition. Pregnant adolescents (aged 14-19 y; n = 71) were recruited; those who initiated breast-feeding on delivery were randomly assigned to a folic acid supplement lactating (SL; 300 micrograms/d, n = 14) group or to a placebo lactating (PL; n = 15) group. Subjects who initiated formula feeding were given a placebo (FF; n = 18). Dietary intakes (two 24-h recalls) were recorded and blood and milk samples were collected at 4, 8, and 12 wk PP. Of the adolescents, 71%, 48%, 67%, and 60% had folate, iron, vitamin B-12, and zinc intakes, respectively, below their predicted requirements. Despite this, most blood indexes were within normal ranges, probably reflecting the subjects' use of supplements during pregnancy. Red blood cell (r = -0.49, P < 0.05) and plasma (r = -0.42, P = 0.08) folate concentrations were negatively correlated with milk zinc concentrations. Mean red blood cell folate content declined between 4 and 12 wk PP among PL (31%) and FF (34%) subjects (P < 0.05) but not among SL subjects. Hence, 300 micrograms folic acid/d was sufficient to prevent a decline in blood folate values of these adolescents PP.