Cereals and Rickets

The effect of decreasing acidity on the solubility of calcium, magnesium and phosphorus in bran and certain pure salt solutions

“…Few experiments have been carried out in which phosphorus was known to exist entirely as phosphate, and in which the Ca:P ratio was high. However, Krieger & Steenbock (1940) found that a high-calcium lowphosphate diet (6:1) fed to rats did not impair bone growth, which appears to contradict the in vitro evidence given above, but two points should be taken into account. First, the experiments with salt solutions have shown that when the concentrations of calcium and phosphorus were reduced and the Ca: P ratio was still high (205 mg. Ca: 32 mg. P), precipitation occurred over a high pH range.…”

“…In mixtures containing phosphorus as phytate and having a lower Ca: P ratio (220 mg. Ca: 115 mg. P) precipitation occurred at higher pH values than in the corresponding high-calcium series, but the quantity of phosphorus soluble at pH 5-0 was still very low, approximately 5 mg. Soluble calcium was 80 mg. at the same pH. Krieger & Steenbock (1940) fed rats on a phytate diet with a ratio of 1:1 and obtained fairly good calcification, but when the ratio was 2:1 calcification was less satisfactory. The figures quoted above indicate that the 2:1 ratio was unsatisfactory because of the early precipitation of phytate and the consequent low hydrolysis of phytate.…”

“…There was a large amount of calcium soluble in these mixtures even at pH 6-5. Diets with high Ca:P ratios and a large proportion of the total phosphorus present as phytate have been shown to give severe rickets in rats (Bruce & Callow, 1934;Lowe & Steenbock, 1936;Krieger & Steenbock, 1940), and it is probable that this was due to the early precipitation of phosphorus as calcium phytate. Mellanby (1949) found that by adding calcium to a phytate diet for puppies the amount of phytate appearing in the faeces was increased, indicating that phytate was more readily precipitated by the extra calcium and this prevented phytase activity.…”

“…In discussing the possible relations between these in vitro results and absorption from the digestive tract the effect of vitamin D cannot be taken into account. This is important since apart from its direct effect on calcium absorption it reduces the inhibitory effect of phytate (Krieger & Steenbock, 1940;Mellanby, 1949).…”

European Conference of the Nutrition Society

“…Recent studies have shown that phytate phosphorus, which is not highly available under certain conditions, is utilized much better when the vitamin D content of the diet is liberal (Krieger and Steenbock, 1940).…”