(P10-012-24) Daily Multiple Micronutrient Supplements Increased Human Milk Iodine and Vitamin A Levels, but Not Vitamin B12 or Folate, Among Lactating Women in Rural Pakistan: RCT Substudy

Objectives: Using human milk (HM) obtained at 3-months postpartum from mothers of term-born infants enrolled in the MaPPS Trial in rural Pakistan (ClinicalTrials.gov: NCT04451395), we aimed to determine whether the concentration of iodine, vitamins A and B12, and folate differed between mothers randomized to receive multiple micronutrient supplements (MMS; UNIMMAP composition) from preconception through to lactation compared to the standard of care (no MMS).

Methods: HM samples (n=186 [intervention=97; control=89]) were collected from a complete breast expression between August 2020 and April 2021 (10 AM-noon); mothers were asked not to feed infants prior to the collection. Only infants fed HM exclusively or predominantly (i.e. water and/or non-nutritive feeds only) were eligible, and mothers receiving MMS had to report ≥50% postpartum MMS adherence. HM iodine concentration was assessed using ICP-MS; vitamin A using HPLC; vitamin B12 using chemiluminescent immunoassay; and folate using microbiological assay. As HM micronutrient data were not normally distributed, arms were compared using the Wilcoxon rank-sum test.

Results: Findings (median [IQR] MMS vs no MMS) showed that MMS improved human milk concentrations of iodine (111 [35,444] vs 79 [48,130] μg/L; P < 0.001) and vitamin A (7.9 [5.2,11.0] vs 6.2 [4.2,8.9] μg/g fat; P < 0.05), but not vitamin B12 (72 [53,106] vs 73 [44,113] pmol/L; P=0.57) or folate (61.7 [47.8,76.6] vs 53.1 [44.7,71.4] nmol/L; P=0.06). HM vitamin A and B12 concentrations were associated with those in maternal serum (P < 0.001 and P < 0.05, respectively). Importantly, few human milk samples in either arm were above existing cut-offs suggested to provide an Adequate Intake of the respective micronutrient to support optimal infant growth and development.

Conclusions: In a population with highly prevalent maternal micronutrient deficiencies, providing a maternal MMS daily from conception through lactation may not produce human milk values above cut-offs. Further research is needed to understand the clinical implications, if any, of these low micronutrient values in human milk.

Funding Sources: Centre for Global Child Health Catalyst Grant, Canadian Institutes of Health Research, Bill and Melinda Gates Foundation