The consumption of beans as a major food-crop in populations suffering from Fe-deficiency is relatively-high. OBJECTIVES: Determine whether a biofortified-variety of cream-seeded-carioca-bean (Phaseolus-vulgaris-L.) could provide more bioavailable-Fe than a standard-variety using in-vivo and in-vitro models.
Studies were designed to mimic the actual-human feeding-protocol. Two carioca-beans, a standard (G4825/58µg-Fe/g) and a biofortified (SMC/106µg-Fe/g), were utilized. Diets formulated to meet the nutrient requirements of Gallus-gallus except for Fe (33.7 and 48.7µg-Fe/g, standard/biofortified-diets, respectively).
In-vitro observations indicated that more bioavailable-Fe was present in the biofortified-beans and diet (P<0.05). In-vivo, improvements in Fe-status were observed in the biofortified-bean-treatment, as indicated by the increased Hemoglobin-Fe, and hepatic-Fe-concentration (P<0.05). DMT-1-expression was increased in the standard-bean-treatment (P<0.05), indicating an absorption upregulation (compensate for less-bioavailable-Fe). Results demonstrate that the biofortified-beans provided more bioavailable-Fe; however, in-vitro, ferritin-formation values were relatively-low. Such-observations are indicative of the presence of high-levels of polyphenols/phytate that inhibit-Fe-absorption. We identified higher-levels of phytate and quercetin-3-glucoside in the Fe-biofortified-bean-variety. Overall, the biofortified-beans moderately improved Fe-status, and that concurrent increase in the concentration of phytate/polyphenols in beans may limit the benefit of increased Fe-concentration. Specific targeting of such compounds during the breeding-process may yield improved dietary-Fe-bioavailability. Also, cecal-contents analysis indicated that Fe-status had altered the composition of the intestinal-microbiome.
Our findings agree with the human-efficacy-trial that demonstrated that the biofortified-carioca-beans improved the Fe-status of Rwandan-women. We suggest the utilization of these in-vitro and in-vivo screening-tools to guide studies aimed to develop and evaluate biofortified staple-food-crops. This approach has the potential to more effectively utilize research-funds and provides a means to monitor the nutritional-quality of the Fe-biofortified-crops.