Calcium and Zinc Absorption from Human Milk, Soy Formula and Dephytinized Soy Formula

Abstract

Dietary calcium (Ca) is essential for regulation of calcium and phosphorus homeostasis and for normal growth and bone development in infants. Some clinical disturbances in the postnatal period may be due to a low bioavailability of Ca from infant diets. Therefore, an adequate supply of Ca is necessary. Little information is available on the absorption of Ca from human milk, soy formula and dephytinized soy formula. To investigate this we used 14 day old rat pups as a model to measure the absorption of Ca. As a comparison, and to verify our model, we also studied the absorption of zinc (Zn). The major objectives of this study were (1) to investigate if a certain level of dephytinization of soy formula leads to a beneficial_ effect on Ca and Zn absorption; and (2) to investigate the influence of various diets on the uptake of Ca by passive diffusion. At this age it is possible to study the latter process, since the vitamin D-regulated active transport of Ca does not occur until rats are about 20 days old (1).