A Method for the Study of Calcium Absorption by the Human Gut Using a Standard Dose of Calcium Labeled with Calcium47

THE process of calcium absorption by the human gut and the factors that affect it in health and in disease are still poorly understood. Workers in this field have been hindered by the lack of convenient methods.1 2 3 4 This aspect of calcium metabolism has been studied chiefly by the metabolic-balance technic, which is not only protracted and difficult but also inherently limited in scope — for example, the net calcium absorption, calculated as a difference between the mean daily ingested and fecal calcium, ignores the part of the fecal calcium contributed by gastrointestinal secretions. Once a suitable isotope such as calcium . . .