Early Life Thiamine Study

Please see attached study protocol for full details.

Background:

Thiamine (vitamin B1) is an essential micronutrient crucial for normal physiological functioning and healthy child development. Thiamine requirements increase with carbohydrate-rich diets (e.g. white rice) and during periods of high metabolism (e.g. perinatal women, infancy). The limited data available show that the prevalence of thiamine deficiency is high in women of childbearing age and their infants in several low- and middle-income settings, notably in South and Southeast Asia, where white rice is the dietary staple, but also in several African countries. Thiamine-deficient pregnant and lactating women produce breastmilk low in thiamine, putting their breastfed infants at risk of deficiency, and potentially fatal beriberi. In addition, recent evidence suggests that sub-clinical thiamine deficiency may be conferred prenatally, placing millions of infants at risk of neurocognitive deficits, undercutting life-long well-being and productivity.

Preliminary Data:

In coordination with the Cambodian Ministry of Health, study investigators undertook a four-parallel-arm, randomized, controlled trial (NCT03616288) in rural Cambodia to estimate the dose of maternal thiamine required postpartum to optimize breastmilk thiamine concentrations; secondary exploratory outcomes included neurocognitive assessments. Mothers were randomized to consume 0, 1.2, 2.4, or 10 mg daily thiamine from 2 weeks through 6 months postnatal. While milk thiamine concentrations were significantly higher in all thiamine groups compared to placebo, critically, at 6 months postnatal, only infants in the 10 mg/d group showed robust neurocognitive benefits. Additionally, infants whose mothers had higher milk thiamine concentrations at our pre-supplementation baseline (2 weeks postpartum) showed significantly improved neurocognitive outcomes at 6 months postnatal, suggesting that infants' prenatal access to adequate thiamine may have critical benefits for neurocognitive development.

Research Gap:

The prior trial indicated that 10 mg/d maternal thiamine supplementation, higher than current recommendations, was needed to support infant neurocognitive development in several domains. However, supplementation started at 2 weeks postpartum. Given how much foundational neurodevelopment occurs from conception through infancy, earlier and longer thiamine supplementation -- starting in pregnancy and maintained through 18 months postnatal -- is likely to further support neurocognitive development.

Design:

This will be a two parallel-arm, double-blind randomized controlled trial to compare the standard dose of thiamine in multiple micronutrient supplements throughout the perinatal and early childhood periods to a higher thiamine dose. Our primary outcome is infant neurocognitive development (Mullen Scales of Early Learning Early Learning Composite, MSEL-ELC) at 18 months postnatal. Secondary neurocognitive outcomes include the MSEL sub-scales, Global Scales of Early Development (GSED), and Visual Paired-Comparison Task (VPC), at 18 months postnatal.

Sample Size:

To detect a mean difference in 3 points in MSEL scores with 90% power (d=0.16, two-tailed α=0.05), and accounting for 20% losses, this study will require N=1,972 participants, 986 per group, to detect the main effect on the primary outcome, MSEL-ELC, at 18 months postnatal.

Statistical Analysis for Primary Outcome:

Scores on MSEL-ELC at 18 months will be compared between groups using a linear-regression model, with adjustment for health center, gestational age at enrolment, and birth anthropometry, and using generalized estimating equations with an independence working-correlation structure to account for multiple births. The effect of treatment will be described as a mean difference with a 95% CI. In all analyses, missing outcome data will be addressed using multiple imputation, performed separately by randomized group using chained equations. Outcomes will be analyzed on an intention-to-treat basis.

This community-based trial will take place in villages throughout Kampong Thom province, Cambodia. Using convenience sampling, pregnant women (either primi- or multi-gravida) will be recruited from antenatal care programs within local health centers in Kampong Thom province.

Inclusion criteria

• women aged 18-45 years
• 12(+0) to 15(+6) weeks pregnant, based on last menstrual period
• planning to breastfeed for at least 6 months

Exclusion criteria

• consumed thiamine-containing supplements in the preceding 3 months
• planning on moving out of province in the next year