title: Effects of calcium carbonate and hydroxyapatite on zinc and iron retention in postmenopausal women.
abstract: We measured the effect of calcium carbonate and hydroxyapatite on whole-body retention of zinc-65 in 11 and iron-59 in 13 healthy, postmenopausal women. In a single-blind, controlled, crossover study, each subject, on three occasions, ingested a standard test meal supplemented with iron-59 or zinc-65 and capsules containing placebo or 500 mg elemental calcium as calcium carbonate or hydroxyapatite. Whole-body countings were performed prior to, 30 min after, and 2 wk after each meal. Mean (SEM) zinc retention was 18.1 +/- 1.0% with placebo (control) and did not vary significantly with calcium carbonate (110.0 +/- 8.6% of control) or hydroxyapatite (106.0 +/- 7.9% of control). Iron retention, 6.3 +/- 2.0% with placebo, was significantly reduced with both calcium carbonate (43.3 +/- 8.8% of control, p = 0.002) and hydroxyapatite (45.9 +/- 10.0% of control, p = 0.003). Iron absorption may be significantly reduced when calcium supplements are taken with meals.
mesh_terms: D000368:Aged; D002119:Calcium Carbonate / Q000494:pharmacology*; D017886:Durapatite; D005260:Female; D005502:Food; D006801:Humans; D006882:Hydroxyapatites / Q000494:pharmacology*; D007408:Intestinal Absorption; D007501:Iron / Q000378:metabolism*; D007504:Iron Radioisotopes; D008593:Menopause; D008875:Middle Aged; D011897:Random Allocation; D014915:Whole-Body Counting; D015032:Zinc / Q000378:metabolism*; D015037:Zinc Radioisotopes
chemical_list: D006882:Hydroxyapatites; D007504:Iron Radioisotopes; D015037:Zinc Radioisotopes; D017886:Durapatite; D007501:Iron; D002119:Calcium Carbonate; D015032:Zinc