Chelated Calcium Supplements
Chelated calcium is one of three broad classifications of calcium supplements. The other two are naturally-derived calcium and refined calcium carbonate. Chelated calcium are synthetic calcium compounds, The most popular chelated calcium is calcium citrate.
According to Whole Foods Magazine:
“Naturally-derived calcium, also known as unrefined calcium carbonate, appears in dietary supplements as bone meal, oyster shell, limestone, and dolomite (clay). Although these forms are typically less expensive than other forms of supplemental calcium, these supplements may also contain significant amounts of lead, a toxic metal that affects the brain, kidney, and red blood cells. Refined calcium carbonate is the most commonly used form of calcium in supplements. It is relatively inexpensive compared to chelated forms of calcium, but has been shown to be less well-absorbed than other forms. To improve absorption, calcium carbonate should be taken with meals, as the presence of food in the stomach causes the secretion of hydrochloric (stomach) acid, a compound that breaks down calcium carbonate.
Chelated calcium is calcium bound to an organic acid, such as citrate, malate, lactate, or gluconate; or to an amino acid, such as aspartate. [Some r]esearch indicates that calcium chelates, especially calcium citrate, are more bioavailable than calcium carbonate.”
Research suggests that calcium chelates mimic the function of food during digestion, keeping the calcium soluble in the intestine. The chelated calcium advantage over calcium carbonate, however, is negated when the latter is taken with food. There is little difference in absorption between calcium chelates and calcium carbonate when food is present.
According to calciuminfo.com:
“A recent study in the Journal of the American College of Nutrition compared the absorption and cost-effectiveness of single doses (500 mg) of commercially-available Os-Cal® calcium carbonate and Citracal® calcium citrate in 24 postmenopausal women. The researchers, led by Dr. Robert P. Heaney, found that both calcium supplements were absorbed equally.”
Heaney et al also noted from the study that calcium citrate with vitamin D reported higher rates of absorption than the same calcium without vitamin D. This is also consistent with calcium carbonate research.
As with any special form calcium, one should examine the research on a calcium chelate for bone density and fracture risk benefits. Some chelated calcium forms have little to no published research available. Calcium citrate and gluconate are two exceptions. You can compare their peformance with that of AdvaCAL, a patented calcium oxide and calcium hyrdroxide combination from Japan. AdvaCAL is not one of the chelated calciums but is created by superheating oyster shell, changing its chemical composition to calcium oxide and hydroxide. In published research, AdvaCAL has shown signficant bone density increases in postmenopausal women and men as well as in elderly women. In some of those same studies, calcium carbonate, even when taken with meals, showed no bone density or fracture risk benefit. Click here to review an independent bone density meta analysis, comparing 32 calcium studies, including AdvaCAL, calcium carbonate and certain forms of chelated calcium.