Intestinal absorption of iron and calcium from soy and cow's milk-based infant formulas in weanling rats pups

Abstract

Objective This study aimed to compare the intestinal absorption of iron and calcium between soy-based and cow's milk- based infant formulas in weanling rats. Methods Twenty male Wistar rats, twenty-one days old on the first day of weaning, were used in this experiment, divided in two Groups, one Group was fed soy protein-based infant formula the other, cow's milk protein-based infant formula. During the study period (ten consecutive days) the animals received food and water ad libitum. Hematocrit and hemoglobin were evaluated on the first, fifth, and tenth days by the Wintrobe and cyanomethemoglobin methods. Feces and urine were collected, beginning on the fifth day, for three consecutive days. On the tenth day, hepatic iron content was also analyzed. Hepatic iron as well as fecal and urinary iron and calcium analyses were performed using an atomic absorption spectrophotometer. At thirty-one days of age, the animals were anesthetized with ketamine and xylazine and sacrificed by exsanguination via the vena cava. Results The final concentration of hemoglobin in the group soy-based infant formula and milk-based infant formula were: 10.3 +/- 1.3g/dL and 10.9 +/- 1.0g/dL (p=0.310). The apparent absorption of iron and calcium, in that order, were: 73.4 +/- 10.2% and 70.2 +/- 9.5%

97.2 +/- 0.7% and 97.6 +/- 1.0% (p=0.501

p=0.290). The apparent calcium retention was: 88.4%+/- 2.2 and 88.6 +/- 2.6%(p=0.848). Hepatic iron content was: 522.0 +/- 121.1mg/g and 527.8 +/- 80.5mg/g (p=0.907). Conclusion Intestinal iron and calcium absorption from soy-based infant formula is similar to that from milk-based infant formula in weanling rats.