The Effect of Dietary Protein Source on Manganese Bioavailability to the Rat

Abstract

Abstract

Rats were fed diets containing 20% protein from casein, beef, chicken, tuna, or soybean. All diets contained 15% fat and were supplemented with limiting amino acids as necessary to meet National Research Council requirements. In Experiment 1, the manganese content of all diets was the same; manganese content was 5 mg/kg. In Experiment 2, a basal (adequate) level of minerals was provided in each diet but total mineral content varied depending on the contribution of the protein source; manganese was added to achieve a concentration of 5 mg/kg. In both experiments, ⁵⁴Mn absorption was greatest from tuna (8.54% and 7.71%) and least from beef (4.57% and 4.14%) (P < 0.0001). In both experiments, biologic half-life of ⁵⁴Mn was longest in rats fed beef (18.5 and 26.9 days) and shortest in rats fed soy (14.5 and 16.2 days) (P < 0.0002). Except for beef, biologic half-life was similar for dietary groups between the two experiments. In Experiment 1, only kidney manganese concentration was significantly affected by diet and was highest in soy-fed animals. In Experiment 2, plasma, kidney, and liver manganese were all significantly affected by diet and were highest in soy-fed animals and lowest in beef-fed animals.