The bioavailability of dietary calcium

This update focuses on the bioavailability of dietary calcium for humans. F undamentals of calcium metabolism, intestinal absorption, urinary excretion and balance are recalled. Dietary factors, especially lactose and other mi lk components, influencing calcium bioavailability at intestinal and renal levels are reviewed. A critical examination of all the methods used for eva luating calcium bioavailability is made. This includes in vitro assays, cla ssical and isotopic balances, urinary excretion, isotope labeling in the ur ine, plasma and bones, long term evaluation of bone mineralization and the use of biological bone markers. Importance and advantages of animal models are discussed. The state of the art in the comparative bioavailability of c alcium in foods is derailed including a comparison of sources of calcium (d airy products and calcium salts) in human studies and in some animal studie s, casein phosphopeptides, proteins, lactose and lactase and their relation with calcium bioavailability tin humans and rats). An update on the consum ption of dairy products and bone mass is presented. Emphasis on peculiariti es and advantages of calcium in milk and dairy products is given.