Effect of calcium and phosphorus salts on the utilization of iron by anaemic rats

In a previous paper, Chapman & Campbell (1957) reported that the addition of relatively large amounts of bone meal to bread diets low in iron retarded haemoglobin regeneration in anaemic rats.In view of the contradictory reports in the literature, mentioned by these authors, about the effect of calcium and phosphorus on the utilization of iron, it was considered desirable to extend this work to determine what effect other calcium salts might have on the utilization of iron when added to bread diets and also to determine the effect of two sodium phosphates.By so doing it was thought that it might be possible to determine whether the calcium or the phosphate portion of the bone meal had caused interference with the utilization of iron. EXPERIMENTAL Plan of experiment.The analytical methods, basal diet, and type of rats used in this study were similar to those already described (Chapman & Campbell, 1957).The project was carried out in two experiments.In Exp.I, bone meal, calcium carbonate, disodium phosphate and commercial sodium hexametaphosphate were used as additives; in Exp. 2, calcium lactate and calcium chloride were used as sources of calcium.The levels of calcium added to these diets were similar to the highest levels used in the earlier work, i.e. equivalent to 7.5 g bone meal/lb.flour (Chapman & Campbell, 1957).Two levels of added ferrous sulphate were employed, o and 10 mg/lb.flour.The two phosphates were added in amounts sufficient to provide the same level of phosphorus as was contributed by the bone meal.Ten rats, five male and five female, were used on each treatment. RESULTSThe iron, calcium and phosphorus content of the diets, the ratios calcium : phosphorus and calcium: iron, the amount of diet consumed per rat in the ro-week period as well as the amounts of iron and calcium consumed per rat are shown in Table I.It can be seen from the analyses of the diets that the flour used in Exp.I contained considerably more iron than that used in Exp. 2. The addition of calcium carbonate and calcium chloride to the diets resulted in a significant decrease in the amount of food consumed; addition of the other salts did not.This reduction in the amount of food consumed has