title: Bioavailability of calcium supplements and the effect of Vitamin D: comparisons between milk, calcium carbonate, and calcium carbonate plus vitamin D.
abstract: Our aim was to examine a regimen for calcium supplementation because various factors seem to be important for its bioavailability, and to examine the effect of adding vitamin D to the supplement. The participants were 20 healthy women aged 28-59 y (chi: 38 y). During the 3-d periods and 1 d before, the participants were consuming a calcium and energy-balanced diet as similar to their usual daily diet as possible. The study was designed as a randomized, placebo-controlled, partly blinded crossover study divided into four periods of 3 d each: 1) three tablets containing 1000 mg CaCO3/d, 2) three tablets containing 1000 mg CaCO3 plus 5 micrograms (200 IU) vitamin D/d, 3)1 L more milk than in the usual daily diet, and 4) three placebo tablets daily. Bioavailability of the different calcium-supplement regimens were evaluated by changes in 24-h urinary excretion of calcium, phosphate, and magnesium. A significant increase in urinary calcium excretion was found during all periods of supplementation compared with the placebo period (P<0.01). Excretion of calcium in the calcium carbonate period was not significantly higher that that in the milk period, but calcium carbonate plus vitamin D resulted in significantly higher calcium excretion compared with that in the milk period. We conclude that the examined calcium carbonate regimen is at least as good a calcium supplement as milk, and that addition of 600 IU vitamin D/d promptly resulted in an increase in urinary calcium excretion after an increase in calcium absorption, even in healthy women.
authors.affiliation: Aarhus Bone and Mineral Research Group, Department of Endocrinology and Metabolism, Aarhus University Hospital, Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Mortensen
authors.forename: P
authors.initials: P
authors.lastname: Charles
mesh_terms: D000328:Adult; D000818:Animals; D001682:Biological Availability; D002118:Calcium / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000652:urine; D002119:Calcium Carbonate / Q000008:administration & dosage / Q000493:pharmacokinetics*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008274:Magnesium / Q000097:blood; D008875:Middle Aged; D008892:Milk; D010710:Phosphates / Q000652:urine; D010919:Placebos; D014807:Vitamin D / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D010710:Phosphates; D010919:Placebos; D014807:Vitamin D; D002119:Calcium Carbonate; D008274:Magnesium; D002118:Calcium