Dietary Calcium and pH of the Lower Intestine. ∗

Abstract

Shortly after weaning, litters of young rats were divided into 5 groups and fed the 5 following diets for 7 to 11 weeks, when they were killed and the pH at various levels of their intestinal tract was determined, using the B.D.H. capillator. The capillator was checked with a potentiometer and in the pH range of 5.5 to 7.5, they checked very well.

All the diets contained corn starch (60.5%-64%), casein (18%), Crisco (10%), dried brewer's yeast (6%), and cod liver oil (2%). This diet with no additions was the mineral deficient diet. In the second diet, 1% K₂CO₃ was added to the mineral deficient diet; in the third, 1% CaCO₃ was added; in the fourth, 1% K₂CO₃ and 1% CaCO₃ were added; and in the fifth, 3.5% of Hawk and Oser's 1 salt mixture was added and this contains approximately as much Ca and K as 1% CaCO₃ and 1% K₂CO₃. The fifth diet was known as the adequate diet.

The pH readings in the stomach, duodenum and jejunum were practically the same regardless of the diet fed. In the rats fed the diets low in calcium (that is, those fed the mineral deficient or the mineral deficient diet +1% K₂CO₃) there was a slightly more acid reaction (pH 6.5-6.6) in the lower ileum than in those fed the other diets, which were rich in calcium, where the pH was from 6.9-7.0. The former rats had abnormally large amounts of fecal material in their lower ileums. 2 The reactions in the cecums of the rats on the calcium poor diets varied from 5.9 to 6.1, as compared with 7.0 to 7.1 in the rats on the calcium rich diets.