Breast milk immune factors in Bangladeshi women supplemented postpartum with retinol or beta-carotene

Background: Vitamin A supplementation of mothers postpartum may improve inf ant health, not only by increasing vitamin A delivery to the infant through breast milk but also by increasing delivery of milk immune factors. Our hy pothesis was that postpartum supplementation with vitamin A increases milk concentrations of certain soluble immune factors. Design: In a double-blind trial conducted in Matlab, Bangladesh, women at 1 -3 wk postpartum were randomly assigned to receive until 9 mo postpartum 1) a single dose of 60 mg retinol as retinyl palmitate followed by daily plac ebos (n = 69), 2) daily doses of 7.6 mg p-carotene (n = 72), or 3) daily pl acebos (n = 71). Milk samples collected at baseline and 3 mo postpartum wer e analyzed by enzyme-linked immunosorbent assay for secretory immunoglobuli n A, lactoferrin, lysozyme, and interleukin 8; by HPLC for total retinol; a nd by atomic absorption spectroscopy for sodium and potassium. Results: After mammary epithelial permeability (defined as an elevated Na:K ) and baseline immune factor concentrations were controlled for, there were no significant treatment effects on immune factors at 3 mo. Increased mamm ary permeability was common (25% of women at baseline and 12% at 3 mo) and was associated with higher concentrations of milk immune factors. Low body vitamin A stores at baseline, as assessed by the modified-relative-dose-res ponse test, were associated with a higher Na:K, but neither retinol nor bet a-carotene supplementation affected the prevalence of increased mammary per meability. Conclusions: Postpartum vitamin A supplementation does not increase milk co ncentrations of immune factors, The causes of increased mammary epithelial permeability in this population require further study.