Bioavailability of Heme-Iron Preparations Derived from Bovine Red Blood Cells

Abstract

In the past, milk has been fortified with inorganic iron compounds. The bioavailability of these compounds for absorption is altered according to the properties of the vehicle. The purpose of this work was to study the possibility of fortifying whole milk with organic iron obtained from fresh bovine red blood cells. The organic iron preparations used in this study were: 1) hemoglobin with stroma, 2) hemoglobin without stroma, 3) hemin. These compounds are soluble in milk and water (with the exception of hemin), do not alter the flavor of the milk, and give the milk a chocolate color. The absorption of these preparations was studied using both whole milk and aqueous solutions as vehicles by a double isotope technique. Seventy healthy infants from 6–18 months old were distributed into five groups: 1) hemoglobin with stroma in whole milk, 2) hemoglobin without stroma in whole milk, 3) hemin in whole milk, 4) hemoglobin with stroma in water, 5) hemin in water. On day 1 each group was given 150 ml milk or water to which were added 2 mg Fe in the form of the heme-iron being studied (hemoglobin with stroma, hemoglobin without stroma, or hemin) and the same product prepared from calf red blood cells that were biologically marked with 55Fe (0.5 μCi/kg). On day 2, the infants received 50 ml of a ferrous-ascorbate solution that contained 2 mg iron (FeSO4) marked with 59Fe (0.1 μCi/kg). Absorption was calculated 14 days later according to circulating radioactivity. The heme-iron preparations in milk showed a geometric mean absorption of 20%. The ratios among the formulas of day 1 in milk and day 2 did not show statistically significant differences. No difference between the absorption of hemoglobin in milk or in aqueous solution was observed; however, the hemin showed a lower absorption value (P < 0.01) in aqueous solution. It can be concluded that fortification of whole milk with hemoglobin preparations is feasible. The addition of hemoglobin preparations to milk appears to be an excellent combination because of the organoleptic characteristics and high bioavailability of iron.