(OR04-03-25) Correlates of Total Vitamin A Liver Reserves Estimated by Retinol Isotope Dilution Among School-Aged Children in the Philippines

Objectives: To characterize correlates of liver vitamin A (VA) stores, assessed through retinol isotope dilution (RID), among school-aged children in an underserved area of the Philippines.

Methods: We conducted a cross-sectional assessment among school-aged children 5-10 years old (n=169) in Sorsogon Province from October to December 2023. We collected information on household sociodemographic characteristics and food security, and children’s dietary intake (past 7-day food frequency intake of preformed VA and proVA-rich foods and 24-hour recalls). Children received a 7 µmol dose of [2H6]-retinyl acetate, followed one week later by a venous blood draw and measurement of weight and height. We measured retinol specific activity by LC/MS/MS and used a published RID equation to estimate total body stores. We calculated liver reserves using body surface area to estimate liver weight and assuming 80% of stores were in the liver.

Results: Food insecurity (69.8%), stunting (30.1%), and thinness (11.5%) were prevalent in the study area. Mean liver stores were 1.00 ± 0.45 μmol/g. Nearly half (48.6%) of the children had stores above the cut-off for hypervitaminosis A ( >1 μmol/g), while no children had deficient stores ( < 0.1 μmol/g), 29.9% had adequate liver stores (0.1-0.7 μmol/g), and 21.5% had high stores (0.7-1.0 μmol/g). Child’s age was the strongest correlate of liver stores (β=-0.19; p< 0.001). Liver stores were higher among children with increasing frequency of intake of milk (β=0.038; p=0.001) and organ meat (β=0.199; p< 0.001) in the past 7 days, but there were no associations between liver reserves and intake of eggs, fortified foods, VA-containing supplements, or proVA-rich foods. Liver stores were positively associated with maternal education (β=0.13; p=0.008). They were not associated with food insecurity or sanitation.

Conclusions: Despite high levels of food insecurity, no children had deficient VA liver reserves, and many children had high liver stores, which were positively correlated with intake of preformed VA. Further research is needed to explore the determinants of high liver stores in this setting, and to investigate potential risks of hypervitaminosis A in settings with high intake of preformed VA, even in the presence of food insecurity.

Funding Sources: This research was funded by the Bill & Melinda Gates Foundation.