Calcium Carbonate BetterThan Calcium Citrate? 

Calcium Carbonate BetterThan Calcium Citrate? 

OMAHA, Neb.--In the June edition of the Journal of the American College of Nutrition (20, 3: 239-49, 2001) (www.am-coll-nutr.org), researchers found that three different calcium preparations offered the same bioavailability. In a randomized, three-way cross-over study, researchers led by Robert Heaney, M.D., from Creighton University, compared single doses (500 mg) of Philadelphia-based GlaxoSmithKline's Os-Cal^® (containing calcium carbonate) and San Antonio, Texas-based Mission Pharmacal's Citracal^® (containing calcium citrate), as well as an encapsulated calcium carbonate with no excipients, on 24 postmenopausal women. Based on multiple blood and urine samples taken during a 24-hour period, results showed that all three calcium supplements produced identical levels of serum calcium.

Researchers also compared the costs of two branded products, citing that Citracal (www.citracal.com) costs between 1.5 to 1.8 times more than Os-Cal (www.oscal.com) per gram of elemental calcium. They concluded that because the supplements "were equally absorbed and had equivalentbioavailability," it may be wiser to invest in the less expensive carbonate product. This study was sponsored byGlaxoSmithCline.

Mission Pharmacal, however, had only seen the study abstract by press time. Bennett Kennedy, Citracal product manager and director of nutritional health, said that the company would be unable to respond to this study's findings due to its limited knowledge of the study's contents. Nonetheless, the company stated that two previous studies conducted by Howard Heller, M.D., and published in the Journal of Clinical Pharmacology in 1999 and 2000 show calcium citrate to have better availability than calcium carbonate. "Although calcium carbonate supplements contain more elemental calcium per pill than calcium citrate, our studies found that calcium carbonate was not as readily available to the body when taken with a meal," Heller stated after conducting the studies.

Kennedy added that studies conducted by the National Institutes of Health (NIH) also corroborate this finding. The agency stated that calcium is more digestible when taken between meals; however, calcium carbonate must be taken with a meal because it is most effectively dissolved in an acidic environment (and will be absorbed with the stomach's digestive-inducing acids). "However, the majority of bone loss occurs at night, when your body is in a fasting state," Kennedy explained. "This is where calcium citrate may be the better choice."