Location: Plant, Soil and Nutrition ResearchTitle: Studies of cream seeded carioca beans (phaseolus vulgaris L.) from a Rwandan efficacy trial: in vitro and in vivo screening tools reflect human studies and predict beneficial results from iron biofortified beans
|REED, SPENSER - Cornell University - New York|
|ANANDARAMAN, AMRUTHA - Cornell University - New York|
|BEEBE, STEVE - International Center For Tropical Agriculture (CIAT)|
Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2015
Publication Date: 9/18/2015
Citation: Tako, E.N., Reed, S.M., Anandaraman, A., Hart, J.J., Beebe, S.E., Glahn, R.P. 2015. Studies of cream seeded carioca beans (phaseolus vulgaris L.) from a Rwandan efficacy trial: in vitro and in vivo screening tools reflect human studies and predict beneficial results from iron biofortified beans. PLoS One. DOI: 10.1371/journal.pone.0138479.
Interpretive Summary: Dietary iron (Fe) deficiency is a health concern caused by a lack of absorbable Fe, mostly in developing countries. Consumption of beans as a food crop in some populations suffering from Fe deficiency is high. Our objective was to determine whether a biofortified variety of carioca bean could provide more absorbable Fe than a standard bean variety, and by using animal (broiler chicken) and cellular (intestinal cells) models. Results indicated that the biofortified bean line was able to moderately improve Fe status, and that concurrent increase in the concentration Fe absorption inhibitors in beans may limit the benefit of increased Fe concentration. Targeting of inhibitors during the bean breeding process may yield improved dietary Fe bioavailability. Our findings have the potential to the means to monitor the nutritional quality of the Fe-biofortified crops once released to farmers.
Technical Abstract: Iron (Fe) deficiency is a highly prevalent micronutrient insufficiency predominantly caused by a lack of bioavailable Fe from the diet. The consumption of beans as a major food crop in some populations suffering from Fe deficiency is relatively high. Therefore, our objective was to 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 (broiler chicken, Gallus gallus) and in vitro (Caco-2 cell) models. Moreover, we conducted these studies under conditions designed to mimic the actual human feeding protocol as closely as possible. Two carioca beans, a standard (G4825; 58ug Fe/g) and a biofortified (SMC; 106ug Fe/g), were utilized, and diets were formulated to meet the nutrient requirements for the broiler except for Fe (dietary Fe concentrations were 33.7 and 48.7 ug/g for the standard and biofortified diets, respectively). In vitro observations indicated that more bioavailable Fe was present in the biofortified beans and in the biofortified bean-based diet. In vivo, improvements in Fe status were observed in the biofortified bean treatment group, as indicated by a significant increase in total body Hb-Fe between days 28–42, and increased hepatic Fe concentration at the study conclusion. Also, mRNA gene expression analysis revealed a significant increase in the expression of DMT–1 in the animals consuming the standard bean diet, indicating an upregulation of absorption to compensate for less bioavailable Fe. Overall, these results demonstrate that the biofortified beans provided more bioavailable Fe; however, it is important to note that the Caco-2 cell results revealed that ferritin formation values were relatively low. As previously shown, such observations are indicative of the presence of high levels of polyphenolic compounds and phytic acid that are known to inhibit Fe absorption. Indeed, we identified higher levels of phytic acid and an increased concentration of the inhibitory flavonoid quercetin 3–glucoside in the Fe biofortified bean variety. Taken together, our results indicate that the biofortified bean line was able to moderately improve Fe status, and that concurrent increase in the concentration of phytate and polyphenols in beans may limit the benefit of increased Fe concentration. Therefore, specific targeting and manipulation of such compounds during the bean breeding process may yield improved dietary Fe bioavailability. In addition, our findings are in agreement with the recent human efficacy trial that demonstrated that the biofortified carioca beans improved the Fe status of Rwandan women. Therefore, we suggest the utilization of these in vitro and in vivo screening tools to guide future 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 once released to farmers.