Food-based approaches for ensuring adequate vitamin A nutrition

Efforts to improve vitamin A (VA) status globally have included supplementation and food fortification. Periodic supplementation results in a cyclic pattern of changing liver VA reserves. Fortification causes a gradual increase in VA liver reserves, but the potential for hypervitaminosis A is present because it is delivered as the preformed vitamin. Programmatically, food-based approaches to improve VA status are often over looked. In part, this is due to perceived poor bioavailability of provitamin A carotenoids from fruits and vegetables and to costs associated with program implementation. However, the bioconversion rate of beta-carotene to VA decreases when liver reserves are adequate, mitigating the potential for hypervitaminosis A with food-based approaches. Biofortification of staple crops with beta-carotene is an emerging strategy to improve VA status in groups at risk of deficiency. Extrapolations from published human and animal studies estimated the potential of biofortified sweet potato and maize to improve VA status of a model boy and adolescent girl compared with supplementation or fortification. A male child (age 0.5 to 4 y) at the 50th percentile of weight-for-age and an adolescent girl (age 13 to 19 y, body weight 35 to 45 kg) were used to calculate liver size and VA accumulation in response to an intervention. In these simulations, a daily sweet potato portion results in a higher relative increase in liver VA concentrations of infants than daily supplements. Biofortified maize consumption caused a steady increase in VA liver concentrations in both model children. In conclusion, provitamin A sources from multiple foods can improve VA status without the potential for hypervitaminosis A.