White common beans (Phaseolus vulgaris) have higher in vitro iron bioavailability than colored seed coat varieties

Abstract

The common bean is an important source of iron in developing countries and there is need to improve their iron bioavailability. This study aimed at screening 21 bean varieties (16 varieties from Uganda and 5 from Columbia) for iron bioavailability with an overall objective of modeling it with respect to key influencing factors; protein, polyphenol, phytate, bean ferritin and iron content. A Caco‐2 cell culture model was used to determine iron uptake from in vitro digested bean samples. Protein content ranged from 25.7–31.6 %; polyphenols, 0.07–0.37 mg/100g; phytates, 0.91–2.17 g/100g; iron, 128.5–154.5 μg/g; bean ferritin, 206–497 μg/g, and relative iron bioavailability (based on 100% bioavailability of ferrous sulfate) was 9.1–52.1%. The two white bean varieties had the highest bioavailability (38–52%) and were significantly different from colored seed coat varieties (9–18%). A fixed effects multiple regression model showed negative effects of polyphenols and phytates and positive effects of iron content. In conclusion, iron bioavailability in common beans is influenced by iron, polyphenol and phytate contents.Source of support: US‐AID under the Dry Grain Pulses CRSP