Chronic Dietary Exposure to Aflatoxin and Stunting in Children Under Five in South West Nigeria: A Biomarker-Based Study

Aflatoxin, a potent mycotoxin produced by Aspergillus species in improperly stored staple crops, has emerged as a potential independent contributor to stunting in sub-Saharan African children through mechanisms including growth hormone disruption, immune suppression, and nutrient malabsorption. However, biomarker-based longitudinal evidence linking chronic aflatoxin exposure to growth faltering in Nigerian children is absent. This study examines the association between biomarker-confirmed chronic aflatoxin exposure and stunting in a prospective birth cohort in Ogun and Ondo States, South West Nigeria. Six hundred pregnant women were enrolled at second trimester and their children followed from birth to 24 months of age with assessments at birth, three, six, twelve, eighteen, and twenty-four months. Aflatoxin B1 lysine adduct in blood, a validated biomarker of chronic dietary exposure, was measured at each child follow-up time point using enzyme-linked immunosorbent assay. Dietary aflatoxin exposure was complemented by sampling and analysis of household staple foods for total aflatoxin content. Linear growth was measured at each assessment, and stunting was defined as height-for-age z-score below negative two. Generalised estimating equations modelled the time-varying association between aflatoxin adduct concentration and growth velocity, adjusting for dietary diversity, breastfeeding, illness burden, socioeconomic status, and maternal height. Effect modification by protein intake was tested given biological interaction hypotheses. Findings will provide the first prospective biomarker-based evidence on aflatoxin-stunting relationships in a Nigerian birth cohort, contributing to the prevention evidence base for food safety as a nutrition intervention. Keywords: aflatoxin, stunting, biomarker, birth cohort, South West Nigeria.