INTESTINAL CALCIUM-ABSORPTION FROM MINERAL-WATER

Little is known about the bioavailability of calcium in water and vari ous beverages. Some mineral waters contain large amounts of calcium th at could compensate for Insufficient consumption of dairy products. Th e fractional intestinal absorption of calcium (FCA) was measured in 12 healthy adult volunteers, using a trace dose of radiocalcium and 200 mg of calcium carrier, part of which was calcium contained in mineral water. Measurements were performed in fasting subjects consuming a sta ndard breakfast. In all the subjects, three mineral waters with a calc ium concentration of 10.4, 78, and 467 mg/l, respectively, were tested . Calcium absorption occurred with the same kinetics for each of the m ineral waters tested, and within 2 h of the oral dose, equilibrium was reached between absorbed calcium and calcium remaining in the gastroi ntestinal tract, which resulted in a constant FCA, value. This Level c omprising between 34.1 and 37.0% was independent of the daily calcium consumption and the chemical content of the mineral water. In conclusi on, calcium contained in mineral waters is available for intestinal ab sorption. In a given normal subject, the only rate-limiting factor for FCA is the amount of total calcium given with foods and drinks. Miner al wafers containing calcium are recommended as a supplemental source of calcium to achieve optimal calcium requirements, especially in aged people with lactose intolerance.