Speakers
Description
Introduction: The long-term benefits or consequences of implementing multiple vitamin A (VA) interventions in the same countries on VA status is currently unknown. Many countries are fortifying multiple foods with preformed VA during processing, including cooking oil, sugar, flour, and snacks.
Methods and Results: African countries now have stable retinol isotope dilution (RID) methods available to assist in monitoring total body stores of VA. In Zambia, in addition to having diets high in provitamin A carotenoids in some areas, multiple VA interventions have been successfully implemented. These include administration of high-dose supplements to children <5 years, mandating sugar fortification, and promoting biofortified orange maize enhanced with -carotene. In one district in Zambia, children (5-7 years) had an alarming prevalence of 59% hypervitaminosis A (>1.0 mol VA/g liver) with high serum provitamin A carotenoid concentrations, and during mango season many children experienced hypercarotenodermia. At baseline, 16% of these children had >5% serum retinol as retinyl esters, a measure of intoxication. Figure 1 shows projections that were made with sugar fortification on total liver reserves in children in Nicaragua. The Zambian children actually show a parallel increase in total liver VA reserves over time. In South Africa, some areas have adequate intake of VA through the consumption of sheep liver. In addition, wheat and maize flours are fortified, and high-dose VA supplements are still mandated to be given to children under the age of 5 years. In one area of South Africa, elevated serum retinyl esters were discovered. In a follow-up study in the same area, 63.6% of children were diagnosed with hypervitaminosis A by RID and it was directly related to the number of VA supplements that they had received during their lifetime. On the other hand, young children in Tanzania would likely benefit from more intensive efforts to improve VA status. However, they need to know which interventions will work best and how to continue to monitor status if they choose to adopt fortified foods. In Burkina Faso, by the time the children had reached school they had an adequate VA status. This was determined by RID before the launch of widespread oil fortification. In the United States, a high prevalence of VA deficiency and hypervitaminosis was discovered in a small group of adults using autopsy samples. Serum retinyl esters were not elevated in those with hypervitaminosis (>1.0 mol/g liver) before toxicity occurred (>3 mol/g liver).
Conclusions: VA deficiency and excess are occurring in the same population groups and causing a double burden with unknown ramifications. RID methods need to be more widely available to be able to diagnose hypervitaminosis A before toxicity occurs. Rising evidence suggests that bone health is affected with excessive VA intakes. This may occur in cases of hypervitaminosis A before toxicity manifests. Population monitoring of VA status is important so that programs can be appropriately targeted or scaled back when adequate status has occurred.
| Institution | University of Wisconsin-Madison |
|---|---|
| Country | USA |
