Calcium bioavailability from a calcium-rich mineral water, with some observations on method

Goals: The study was designed to determine whether high-calcium mineral water is an efficient additional source of dietary calcium, optimizing a method for calcium determination never used for mineral waters. Background: It is generally agreed that an adequate calcium intake is necessary for the acquisition of an ideal peak bone mass and for the maintenance of the bone mineral density in adults, in postmenopausal women, and in the elderly. Mineral waters are calorie free, and some, with high calcium levels, might be significant sources of calcium. Study: The availability of the calcium contained in a high-calcium mineral water was measured in 27 healthy subjects. In 8 subjects the calcium availability of the water was compared with the calcium availability ingested with milk at the same calcium load. Milk and water were labeled extrinsically with 30 mg Ca-44. Fractional absorption from the oral dose was determined from plasma samples using ICP-MS technique. Results: At an ingested calcium load of 3.18 mmol, percentage of absorption for water averaged 22.53 +/- 2.53 (mean +/- SD) for men, 22.57 +/- 2.10 (mean +/- SD) for premenopausal women and 21.62 +/- 3.12 (mean +/- SD) for postmenopausal women. Percentage absorption from milk was 23.15 +/- 4.06 (mean +/- SD). Discussion: The calcium from the mineral water is thus highly bioavailable, at least as bioavailable as milk calcium, and ICP-MS appears to represent a reliable and reproducible method for calcium absorption from alimentary sources.