Effect of Lactose on Calcium Metabolism in Man

1 The effect of lactose on the absorption and excretion of calcium was studied in three patients under controlled dietary conditions in the Metabolic Research Ward. Simultaneous Ca45 and Sr85 absorption studies were carried out in one of the patients. 2 Lactose given in amounts up to 50 gm/day did not decrease the urinary excretion of calcium nor did it improve the calcium balance. No consistent effect on phosphorus or nitrogen metabolism was noted. 3 The radioisotope studies carried out in a single patient indicate that the absorption of Ca45 and Sr85 was improved slightly in the lactose phase.