Absorbability and cost effectiveness in calcium supplementation.
BACKGROUND
Cost-effectiveness of calcium supplementation depends not only on the cost of the product but on the efficiency of its absorption. Published cost-benefit analyses assume equal bioavailability for all calcium sources. Some published studies have suggested that there are differences in both the bioavailability and cost of the major calcium supplements.


METHODS
Randomized four period, three-way cross-over comparing single doses of off-the-shelf commercial calcium supplements containing either calcium carbonate or calcium citrate compared with a no-load blank and with encapsulated calcium carbonate devoid of other ingredients; subjects rendered fully vitamin D-replete with 10 microg/day 25(OH)D by mouth, starting one week prior to the first test.


METHODS
24 postmenopausal women


METHODS
Pharmacokinetic analysis of the increment in serum total and ionized calcium and the decrement in serum iPTH induced by an oral calcium load, based upon multiple blood samples over a 24-hour period; measurement of the rise in urine calcium excretion. Data analyzed by repeated measures ANOVA. Cost calculations based on average retail prices of marketed products used in this study from April through October, 2000.


RESULTS
All three calcium sources (marketed calcium carbonate, encapsulated calcium carbonate and marketed calcium citrate) produced identical 24-hour time courses for the increment in total serum calcium. Thus, these were equally absorbed and had equivalent bioavailability. Urine calcium rose slightly more with the citrate than with the carbonate preparations. but the difference was not significant. Serum iPTH showed the expected depression accompanying the rise in serum calcium, and there were no significant differences between products.


CONCLUSIONS
Given the equivalent bioavailability of the two marketed products, the cost benefit analysis favors the less expensive carbonate product.
Heaney
R P
RP
Creighton University, Osteoporosis Research Center, Omaha, Nebraska 68131, USA. rheaney@creighton.edu
Dowell
M S
MS
Bierman
J
J
Hale
C A
CA
Bendich
A
A
D019540:Area Under Curve; D001682:Biological Availability; D002118:Calcium / Q000032:analysis*; D002119:Calcium Carbonate / Q000008:administration & dosage / Q000191:economics / Q000493:pharmacokinetics; D019355:Calcium Citrate / Q000008:administration & dosage / Q000191:economics / Q000493:pharmacokinetics; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000191:economics* / Q000493:pharmacokinetics*; D003362:Cost-Benefit Analysis; D018592:Cross-Over Studies; D019587:Dietary Supplements / Q000191:economics*; D005260:Female; D050723:Fractures, Bone / Q000517:prevention & control; D006801:Humans; D007408:Intestinal Absorption; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000517:prevention & control; D017698:Postmenopause
D002136:Calcium, Dietary; D002119:Calcium Carbonate; D019355:Calcium Citrate; D002118:Calcium