Iron Bioavailability from Multiple Biofortified Foods Using an in Vitro Digestion, Caco-2 Assay for Optimizing a Cyclic Menu for a Randomized Efficacy Trial (P10-029-19)

Abstract

ObjectivesA multiple biofortified food crop trial targeting iron, zinc, and vitamin A deficiencies among young children and their breastfeeding mothers is planned in India. We sought to determine iron bioavailability from biofortified and conventional crop mixes representative of planned meal components. MethodsA 24-meal menu was developed based on pearl millet, sweet potato, and lentils targeted for a feeding trial. Crops were procured from India, cooked, and freeze-dried before two rounds of an established in vitro digestion/Caco-2 iron bioavailability assay. Samples used a fixed weight adjusted for sweet potato water content. Representative crop proportions were determined using k-means clustering, combined such that samples included either all biofortified or all control crop varieties, and analyzed in triplicate. Outcomes were Caco-2 iron uptake and uptake normalized to iron per sample for fractional bioavailability. Data were analyzed with generalized linear models in SAS accounting for crop proportions and variety. ResultsAcross both experiments, biofortified pearl millet alone demonstrated higher iron uptake than conventional varieties (5.01 ± 1.66 vs. 2.17 ± 0.96 ng ferritin/mg protein, P ≤ 0.036). Addition of sweet potato to pearl millet did not change iron uptake for biofortified varieties (P ≥0.13), but increased control iron uptake for all amounts of sweet potato (P ≤ 0.006), which did not differ from biofortified varieties (P ≥ 0.08). Lentil proportion increased iron uptake (β = 4.6 ± 2.2, P = 0.009), with no effect of variety or a lentil by variety interaction (P ≥ 0.56). The overall effect estimate of biofortified vs. control was (β = 1.79 ± 0.91, P = 0.08). Iron uptake normalized to iron per sample was higher for control crops (P ≤ 0.02), and enhanced by sweet potato, while inhibited by pearl millet (both P < 0.001). ConclusionsA Caco-2 assay predicts that biofortified pearl millet alone has greater iron bioavailability than control pearl millet. The addition of sweet potato and lentils increased overall and relative iron bioavailability, while reducing differences between biofortified and control varieties. Matrix effects, processing, and promoters/inhibitors of iron absorption should be considered in addition to total iron concentration when optimizing iron bioavailability. Funding SourcesThis work was supported by HarvestPlus and the USDA. Supporting Tables, Images and/or Graphs▪