Studies on the Sulfur Metabolism in Infants Part 2. The Sulfur Metabolism in Infants under Breast Feeding and in Infants under Artifical Feeding

By the new method as described in Part I the author studied the sulfur and nitrogen metabolism in infants under breast feeding and in infants under artificial feeding, and obtained the following results. 1. In the infants under breast feeding at the age of 1-2 months, 3-4 months, and 5-6 months old the average sulfur retention at each period has bead 25.7, 33.7, and -0.53 per cent respectively. Similarly in the infants under artificial feeding at the same age range the average retenrion has beed 35.1, 48.6 and 40.4 per cent respectively. 2. In the case of the infants under breat feeding at the age of 5-6 months old the quantity of sulfur retained gives a negative value, but this seems to be due to an increased urinary excretion of sulfur in the process of the conversion of cartilage to bone. 3. The nitrogen retention rate shows no difference due to feeding methods. 4. Nitrogen-sulufr ratio (N/S) of the retention differs according to the method of feeding. Namely, the ratio N/S in infants under breast feeding is 25.2 while that in infants under artificial feeding is 18.8. 5. N/S values of the retention in infants under breast feeding are higher than those in infants under artificial feeding. This fact indicates that sulfur in breast milk is more effective than that in cow's milk for increasing the quantity of nitrogen to be retained, and this in turn seems to be due to the action of cystine-sulfur contained in breast milk