ARS | Publication request: Biofortified red mottled beans (phaseolus vulgaris L.) in a maize and bean diet provide more bioavailable iron than standard red mottled beans: studies in poultry (Gallus gallus) and an in vitro digestion/Caco-2 model

Submitted to: Nutrition Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 14, 2011
Publication Date: October 14, 2011
Citation: Tako, E.N., Blair, M., Glahn, R.P. 2011. Biofortified red mottled beans (phaseolus vulgaris L.) in a maize and bean diet provide more bioavailable iron than standard red mottled beans: studies in poultry (Gallus gallus) and an in vitro digestion/Caco-2 model. Nutrition Journal. 10:113.

Interpretive Summary: The objective was to compare the capacities of biofortified and standard colored beans to deliver iron (Fe) for hemoglobin synthesis. Two isolines of large-seeded, red mottled Andean beans (Phaseolus valgaris L.), one standard (“Low FE”) and the other biofortified (“High Fe”) in Fe (49 and 71 ug Fe/g, respectively) were used. This commercial class of red mottled beans is the preferred varietal type for most of the Caribbean and Eastern and Southern Africa where almost three quarters of a million hectares are grown. Therefore it is important to know the affect of biofortification of these beans on diets that simulate human feeding studies. For that, Maize-based diets containing the beans were formulated to meet the nutrient requirements for broiler except for Fe (Fe concentrations in the 2 diets were 42.9+/-1.2 and 54.6+/-0.9 mg/kg). One day old chicks (Gallus gallus) were allocated to the experimental diets (n=12). For 4 wk, hemoglobin, feed-consumption and body-weights were measured. Results indicated that Hemoglobin maintenance efficiencies (HME) (means +/-SEM) were different between groups on days 14 and 21 of the experiment (P<0.05). Final total body hemoglobin Fe contents were different between the standard (12.58 +/- 1.0 mg {+/-0.228+/-0.01 umol}) and high Fe (15.04 +/- 0.65 mg {0.273+/-0.01 umol}) bean groups (P <0.05). At the end of the experiment, tissue samples were collected from the intestinal duodenum and liver for further analyses. Divalent-metal-transporter-1, duodenal-cytochrome-B, and ferroportin expressions were higher and liver ferritin was lower (P<0.05) in the standard group vs. the biofortified group. In-vitro analysis showed lower iron bioavailability in cells exposed to standard (“Low Fe”) bean based diet. We conclude that the in-vivo results support the in-vitro observations; biofortified colored beans contain more bioavailable-iron than standard colored beans. In addition, biofortified beans seem to be a promising vehicle for increasing intakes of bioavailable Fe in human populations that consume these beans as a dietary staple. This justifies further work on the large-seeded Andean beans which are the staple of a large-region of Arica where iron-deficiency anemia is a primary cause of infant death and poor health status.

Technical Abstract: The objective was to compare the capacities of biofortified and standard colored beans to deliver iron (Fe) for hemoglobin synthesis. Two isolines of large-seeded, red mottled Andean beans (Phaseolus valgaris L.), one standard (“Low FE”) and the other biofortified (“High Fe”) in Fe (49 and 71 ug Fe/g, respectively) were used. This commercial class of red mottled beans is the preferred varietal type for most of the Caribbean and Eastern and Southern Africa where almost three quarters of a million hectares are grown. Therefore it is important to know the affect of biofortification of these beans on diets that simulate human feeding studies. For that, Maize-based diets containing the beans were formulated to meet the nutrient requirements for broiler except for Fe (Fe concentrations in the 2 diets were 42.9+/-1.2 and 54.6+/-0.9 mg/kg). One day old chicks (Gallus gallus) were allocated to the experimental diets (n=12). For 4 wk, hemoglobin, feed-consumption and body-weights were measured. Results indicated that Hemoglobin maintenance efficiencies (HME) (means+/-SEM) were different between groups on days 14 and 21 of the experiment (P<0.05). Final total body hemoglobin Fe contents were different between the standard (12.58+/-1.0 mg {+/-0.228+/-0.01 umol}) and high Fe (15.04+/-0.65 mg {0.273+/-0.01 umol}) bean groups (P <0.05). At the end of the experiment, tissue samples were collected from the intestinal duodenum and liver for further analyses. Divalent-metal-transporter-1, duodenal-cytochrome-B, and ferroportin expressions were higher and liver ferritin was lower (P<0.05) in the standard group vs. the biofortified group. In-vitro analysis showed lower iron bioavailability in cells exposed to standard (“Low Fe”) bean based diet. We conclude that the in-vivo results support the in-vitro observations; biofortified colored beans contain more bioavailable-iron than standard colored beans. In addition, biofortified beans seem to be a promising vehicle for increasing intakes of bioavailable Fe in human populations that consume these beans as a dietary staple. This justifies further work on the large-seeded Andean beans which are the staple of a large-region of Arica where iron-deficiency anemia is a primary cause of infant death and poor health status.