Iron from Gastrointestinal Sources Excreted in the Feces of Human Subjects

Abstract

Young women were given diets, the mean content of which was 1.03, 2.15 and 3.22 mg of iron during three 8-day periods respectively. The iron in the food and feces and the nitrogen in the food, feces and urine were determined. The amount of iron in the feces from gastrointestinal sources was calculated by two methods. (1) A regression of the values for fecal-iron on food-iron was extended to zero. The calculated value for fecal-iron at zero intake was 0.17 mg. (2) The percentage absorption at which the gastrointestinal iron in the feces appeared to be the most constant for the three levels of intake was determined. By this calculation, the absorption for the three intakes lay between 18 and 25% and the value for gastrointestinal iron lay between 0.12 and 0.27 mg. By either method of calculation, the mean value for daily gastrointestinal iron in the feces approximated 0.2 mg. To determine the relationship between the dry weight and the iron content of the feces, a correlation between dry fecal-weight and fecal-iron was calculated for each subject. The correlations were highly significant except for two subjects who had been given mineral oil and whose fecal excretions were delayed more than for the other subjects. The amount of nitrogen retained by each subject on the three diets was determined to aid in the evaluation of the adequacy of the diet. The mean protein intake for the three periods was 59, 74 and 81 gm respectively. Although most of the protein was from milk, some subjects did not retain nitrogen during the first two periods. The amount of nitrogen retained by an individual reflected the protein intake of that person previous to the experimental period.