A study of five calcium supplements: estimation of calcium absorption and sodium content

Calcium absorption from five proprietary calcium supplements (Calcium-Sandoz, Cal-Sup, Effercal, Oscal and Oscal Chewable) was examined in 12 healthy female volunteers. Supplements providing 1 g of elemental calcium were studied in random order at weekly intervals. Using increments in urinary calcium excretion as an index of absorption, Calcium-Sandoz was absorbed best and Oscal the least. However, interindividual variation of calcium absorption appeared at least as significant as variation between the supplements themselves. Sodium content of the supplements was insignificant for all except Calcium-Sandoz which included 0.4 g of sodium/g of calcium (equivalent to 1 g of NaCl). This amount represents a substantial proportion of the recommended daily intake for those on a sodium-limited diet.