Dietary Iron Levels Research Articles

Effect of Na EDTA in Diets of Different Iron Levels on Utilization of Calcium, Phosphorus and Iron by Rats

One hundred seventy growing rats were utilized in 2 experiments (Initial weight 150 and 60 gm.) to evaluate the effect of Na2EDTA in diets ranging to 4510 ppm of iron on calcium and phosphorus balance, bone and blood values. The higher levels of iron reduced gain; gain-feed ratio; bone ash, calcium and phosphorus and serum calcium, but increased serum phosphorus and liver iron. In balance studies urinary phosphorus and percent iron retained were reduced while urinary calcium and iron and fecal phosphorus and iron increased as dietary iron increased. Addition of ethylenediaminetetraacetic acid (Na2EDTA) to the diet increased weight gain and bone ash in the diets containing the high iron levels when calcium was fed at 1.02% (Experiment 1) of the diet, but had little effect when dietary calcium was reduced to 0.59% (Experiment 2). The excretion of fecal phosphorus and fecal ash was reduced and the absorption and retention of phosphorus were increased when Na2EDTA was included in the diet. The increasing urinary excretion of iron and the increased iron retention as evidenced in part by higher liver iron levels indicated that the “mucosal block” was only partially effective in limiting iron absorption. This was further substantiated by the increased iron retention at the highest level of dietary iron.

Effects of Dietary Iron Level on Gut Iron Levels and Iron Absorption in the Rat

The proposal that the iron content of the intestine is of critical importance in determining the rate of iron absorption was examined in Sprague-Dawley rats. The iron content of the rat gut was found to vary with the iron content of the diet but the relationship was not a linear one. The more proximal sections of the gut were more sensitive to dietary iron level than the distal portions. Rats fed stock ration had much lower proximal gut iron levels than rats fed purified diets of lower iron content. The iron content of the gut appeared to influence, within limits, the absorption of 59Fe from an isolated gut loop. When rats were transferred from a high iron diet to a low iron diet, a steady depletion of iron from the gut was accompanied by an increase of iron absorption which was maximum on the third to fifth day after the change of diet. In the reverse experiment, iron absorption was almost immediately depressed concomitant with the elevation of the gut iron level. The iron content of the mucosa did not appear to influence the entrance of the test dose of iron into the mucosa. Rather, the major point of mucosal regulation appeared to be the transfer of iron from the mucosa to the blood supply. The failure of a large dose of iron placed in the jejunum to influence immediately the absorption of 59Fe from a duodenal loop indicates that extra-mucosal (hormonal?) control of iron absorption is minimal or lacking.

The effect of different levels of dietary iron and calcium upon the iron content of the femur and incisor of the rat

Weanling rats were maintained for eleven weeks on purified diets containing normal (0.025 per cent) and high (0.16 per cent) iron. These levels of iron were associated with either normal (0.56 per cent) or low (0.03 per cent) dietary calcium. The femora and incisors of each animal were examined for ash content and the iron content of femur, dentine and enamel estimated polarographically. Excess dietary iron significantly depressed the ash content of bone and dentine at both levels of dietary calcium. Both calcium deficiency and iron excess produced an increase in iron content of the bone whereas iron excess alone increased the concentration of the element in dentine. Neither ash content nor iron concentration in enamel was affected by the variations in the diets.

A STUDY OF THE PROLONGED INTAKE OF SMALL AMOUNTS OF ETHYLENEDIAMINETETRAACETATE ON THE UTILIZATION OF LOW DIETARY LEVELS OF CALCIUM AND IRON BY THE RAT

Young rats were maintained for 84 days on a diet which supplied to each 0.15 mg of iron and 4.26 mg of calcium per day. The Ca:P ratio of the diet was 1.4. For some of the animals the dihydrate of disodium ethylenediaminetetraacetic acid (EDTA) was added at a level of 0.01%, which supplied 1 mg per rat per day. The molar ratio of EDTA:Ca:Fe was 1:37.9:1.The EDTA did not affect the growth of the rats. It did not affect the excretion of calcium, or its concentration in blood serum or femur. Since the faecal excretion was not affected, apparently the absorption was not impaired. The growth of the femur was not affected. EDTA was associated with generally higher levels of iron in the serum, but the average difference was not statistically significant. There was no effect upon the liver iron or the haemoglobin level in the blood.Small amounts of EDTA in the diet apparently did not interfere with the utilization of low and probably inadequate dietary levels of calcium and iron.

A STUDY OF THE PROLONGED INTAKE OF SMALL AMOUNTS OF ETHYLENEDIAMINETETRAACETATE ON THE UTILIZATION OF LOW DIETARY LEVELS OF CALCIUM AND IRON BY THE RAT

Young rats were maintained for 84 days on a diet which supplied to each 0.15 mg of iron and 4.26 mg of calcium per day. The Ca:P ratio of the diet was 1.4. For some of the animals the dihydrate of disodium ethylenediaminetetraacetic acid (EDTA) was added at a level of 0.01%, which supplied 1 mg per rat per day. The molar ratio of EDTA:Ca:Fe was 1:37.9:1.The EDTA did not affect the growth of the rats. It did not affect the excretion of calcium, or its concentration in blood serum or femur. Since the faecal excretion was not affected, apparently the absorption was not impaired. The growth of the femur was not affected. EDTA was associated with generally higher levels of iron in the serum, but the average difference was not statistically significant. There was no effect upon the liver iron or the haemoglobin level in the blood.Small amounts of EDTA in the diet apparently did not interfere with the utilization of low and probably inadequate dietary levels of calcium and iron.