Neurocognitive Benefits of Maternal Thiamine Supplementation for Breastfed Cambodian Infants

Abstract Objectives Women reliant on rice-heavy diets can have inadequate thiamine intakes, placing breastfed infants at risk of thiamine deficiency and, in turn, neurocognitive impairments. We investigated the impact of maternal thiamine supplementation doses on infants’ cognitive, motor, and language development across the first year. Methods In this double-blind, four-parallel arm, randomized controlled trial, healthy mothers of exclusively breastfed newborn infants were recruited in Kampong Thom, Cambodia. At 2-weeks postnatal, women (n = 335) were randomized to one of four treatment groups to consume one capsule/day with varying amounts of thiamine for 22 weeks: 0 mg, 1.2 mg, 2.4 mg, and 10 mg. At 2-, 12-, 24- and 52-weeks of age, infants were assessed with the Mullen Scales of Early Learning (MSEL). Results Mixed effects modeling suggest that by 6 months of age, the highest maternal thiamine dose (10 mg/day) held significant benefits for infants’ language development, F's (3,659) > 33.2, P's < 0.001, but generally not for motor or visual reception development. Despite having achieved standardized scores on the MSEL that approximated US norms by 6 months, infants showed a significant drop in all cognitive domains following trial completion, indicating that nutritional interventions beyond 6 months may be necessary. Conclusions Findings provide the first experimental evidence that thiamine supplementation among lactating mothers at risk of thiamine deficiency protects their infants’ neurocognitive development, with particular benefit to developing language capacities. Results are consistent with studies that report a widening gap in cognitive test scores over time between children from high vs. low-risk contexts. Important questions remain, particularly with respect to the appropriate duration of thiamine supplementation and/or alternate interventions such as mandatory fortification, with potential to build protective stores of thiamine in preconception or pregnancy. Funding Sources Bill & Melinda Gates Foundation and the New York Academy of Sciences (Opportunity ID OPP1176128).