Five minutes following the oral administration, each subject will be infused intravenously with 1.5 mg of CaCl2 labeled with 42Ca over 10 min. Over the following 24 h subjects will consume meals that will be selected by the Unit of Clinical Nutrition at Sourasky Medical Center nutritionist on the basis of their food diary and ALL urine excreted during this time should be collected in a designated urine container and returned to the Unit of Clinical Nutrition at Sourasky Medical Center for evaluation. The same protocol as in day 0 with a crossover oral treatment will be performed after 21 day washout period.