Biofortified black beans in a maize and bean diet provide more bioavailable iron to piglets than standard black beans.

Our objective was to compare the capacities of biofortified and standard black beans (Phaseolus vulgaris L.) to deliver iron (Fe) for hemoglobin (Hb) synthesis. Two lines of black beans, one standard and the other biofortified (high) in Fe (71 and 106 microg Fe/g, respectively), were used. Maize-based diets containing the beans were formulated to meet the nutrient requirements for swine except for Fe (Fe concentrations in the 2 diets were 42.9 +/- 1.2 and 54.6 +/- 0.9 mg/kg). At birth, pigs were injected with 50 mg of Fe as Fe dextran. At age 28 d, pigs were allocated to the experimental diets (n = 10). They were fed 2 times per day for 5 wk and given free access to water at all times. Body weights and Hb concentrations were measured weekly. Hb repletion efficiencies (means +/- SEM) did not differ between groups and, after 5 wk, were 20.8 +/- 2.1% for the standard Fe group and 20.9 +/- 2.1% for the high Fe group. Final total body Hb Fe contents did not differ between the standard [539 +/- 39 mg (9.7 +/- 0.7 micromol)] and high Fe [592 +/- 28 mg (10.6 +/- 0.5 micromol)] bean groups (P = 0.15). The increase in total body Hb Fe over the 5-wk feeding period was greater in the high Fe bean group [429 +/- 24 mg (7.7 +/- 0.4 micromol)] than in the standard Fe bean group [361 +/- 23 mg (6.4 +/- 0.4 micromol)] (P = 0.034). We conclude that the biofortified beans are a promising vehicle for increasing intakes of bioavailable Fe in human populations that consume beans as a dietary staple.