Effect of phytate reduction of sorghum on zinc availability as assessed by in vitro dialysability, Caco‐2 cell uptake, and suckling rat pups

Abstract

Improved zinc availability from sorghum will benefit many malnourished communities in the least developed countries in the world, having a high prevalence of zinc deficiency. We evaluated the effect of genetic phytate reduction on zinc accessibility and uptake measured by dialysability and Caco‐2 cell uptake assays and compared those results with those from zinc absorption measured by a suckling rat pup model. Phytate reduction (80–86%) in these sorghum samples significantly increased zinc uptake and absorption. The dialysability assay was not successful in estimating zinc absorption, probably due to the nature of zinc to get adsorbed to the dialysis membrane and to precipitate. The phytate reduction resulted in the phytate:zinc molar ratio being decreased from 21.8 – 27.0 to 3.0 – 5.1, well below the critical point for inhibition of zinc uptake (10 – 15), which supports the uptake and absorption results. Caco‐2 cells can be used to estimate the zinc absorption of genetically reduced phytate sorghum.We are grateful to the Bill and Melinda Gates Grand Challenges 9, Africa Biofortified Sorghum (ABS) Project through a sub‐grant from HarvestPlus for funding this research