The Utilization of the Iron of Protein Foods by the Albino Rat

Abstract

Two series of experiments were conducted to ascertain: 1.—the relative values of beef muscle, beef liver, beef kidney, peanuts, eggs, pecans and English walnuts, as sources of iron, when each food served as a source of protein supplementary to milk powder, and 2.—the relative values of milk powder, beef muscle, beef liver, beef kidney, beef brain, eggs and peanuts as sources of iron, when each served in the diet as the sole source of protein and iron. The experimental subjects were albino rats which were fed individually for fifteen weeks. The best growth resulted from the diet in which the sources of protein were milk powder and pecans, though excellent growth also resulted from the diet in which milk powder was the sole source of protein. Milk powder as a source of protein, when supplemented with beef muscle, eggs, peanuts and English walnuts afforded good growth, while somewhat inferior performance resulted from milk powder and liver, and milk powder and kidney. When serving as the sole source of protein in the diet, beef muscle, beef kidney, beef liver and eggs, all supported good growth, but were excelled in this respect by milk powder. Poor growth resulted from diets deriving their protein from beef brain, beans and peanuts. The values of protein foods fed supplementary to milk powder, as sources of iron, were stated on the basis of absolute quantities stored, and on the basis of the contents of iron in the bodies of the rats on the fresh, the dry, and the fat-free dry basis. On the absolute basis beef muscle, beef liver, and pecans were superior sources of iron; kidney, eggs, and peanuts were of moderate value; while English walnuts and milk powder were the poorest sources of this nutrient. On the fresh and the fat-free dry bases beef muscle, beef liver, and beef kidney were superior sources of iron; eggs and peanuts were of moderate value; while pecans, walnuts and milk appeared to be the poorest sources of iron. The dry body weight of the rat appeared not to be a significant basis of reference for iron contents. As sole sources of iron, reckoned on the basis of the fresh body weights, beef muscle, beef liver, beef kidney, and eggs were superior sources of iron, while milk as usual rated poorest in this regard, the status of brain, beans, and peanuts appearing in an unfavorable light but being questionable because of the poor or irregular growth of the rats.