Calcein's Quenching In Vitro Method for Assessing Dietary Iron Bioavailability

Abstract

Low iron bioavailability (IBA) is a major contributor of iron deficiency anemia, a most prevalent nutritional deficiency around the world. In vitro IBA is commonly measured using simulated gastrointestinal digestion, caco‐2 cell uptake and followed by ferritin response measurement. This method is cumbersome since it takes more than 24 hours and needs an expensive kit to measure ferritin concentrations. Hence, our objective was to develop a high throughput and cost effective method to assess IBA in large number of samples in a short period of time. In this new method, the quenching of calcein fluorescence in a caco‐2 cell model by food iron following in vitro digestion is used as an index of IBA. The meals we used were similar to the ones that were used in human studies. IBA assessed in this method was compared with published human absorption data and measured ferritin responses. Similar to human absorption data, IBA was enhanced by ascorbic acid, and was reduced by bran, phytate, and tea. A high correlation was found between published human absorption data and the IBA we tested (r=0.90; p=0.04). Our data was also highly correlated with the data obtained using traditional ferritin method (r=0.92; p<0.01). In conclusion, our method does not only reliably predict human iron absorption, but also is a more cost effective and faster one compared to the widely used ferritin method. However, future studies are needed for more comparisons with human studies.