Although calcium may not be the most exciting supplement sitting on your shelf, with sales of nearly $263 million last year according to Information Resources Inc. data, it is by far the best-selling mineral you stock.
And with consumers getting the message from The National Institutes of Health, the surgeon general and the Institute of Medicine that they need more calcium— the recommend daily calcium intake is between 1,000 and 1,500 milligrams— sales are poised to grow.
Manufacturers are responding by putting research dollars into the mineral and introducing innovative calcium and bone-health products.
New calcium forms boost bioavailability more than the old standby calcium carbonate. Other nutrients are being added that also help boost calcium absorption, including magnesium, phosphorus, vitamin D and prebiotic fibers like inulin. And new research is leading to the successful introduction of vitamin K2 (sometimes seen on labels as menaquinone-7 or MenaQ-7) as an ingredient not just good for your bones but also for your heart.
Are simple calcium-only supplements a thing of the past? "The stand-alone calcium supplement can still be useful to those who are getting enough of the other bone-building nutrients elsewhere, like vitamins D and K, magnesium and trace minerals," says Kevin Connolly, Ph.D., director of scientific affairs and product development at Jarrow Formulas, based in Los Angeles. "The differences in cost, ease of formulation and physical attributes, like solubility and net yield, still make certain forms of calcium more advantageous than others for certain applications."
Rainbow Light takes a different tack with its Food-Based Calcium, a top 10 seller in natural products stores. The formula starts with calcium carbonate, which has a lower molecular weight that allows for higher potency per tablet (and is cheaper to source— another reasonmanufacturers love it). Then it's mixed with calcium citrate and amino acid chelate, forms of calcium considered to be more bioavailable than carbonate. This formula reflects the traditional ratio of 2 milligram of calcium for every 1 milligram of magnesium.
"Approximately 50 percent of all the magnesium in the body is found in the bones," says Marci Clow, R.D., senior director of product research for Rainbow Light Nutritional Systems, based in Santa Cruz, Calif. Surprisingly, there is very little research aimed at determining the optimal ratio of calcium to magnesium in the diet."
Importance of magnesium
If there is but one lesson to learn about calcium supplements, it is that they must also contain magnesium.
"The hidden cause of calcium deficiency is the fact that available calcium is not being assimilated by the body due to a lack of magnesium," says Ken Whitman, vice president of marketing at Burbank,Calif.-based Peter Gillham's Natural Vitality. "Without a proper balance of these two minerals, magnesium gets depleted, which will result in the negative effects associated with lack of magnesium and a buildup of unassimilated calcium."
Much of the calcium research focuses on absorption of the mineral.
A 2001 study found no difference in absorption between calcium carbonate or citrate (Journal of the American College of Nutrition, 2001). But a 2002 study by researchers at the University of Texas Southwestern Medical Center found calcium citrate was much better absorbed than calcium carbonate by postmenopausal women who were not on estrogen therapy or who had low vitamin D stores. When they compared bioavailability of the two calcium forms on women who were taking estrogen, however, the results were the same.
Those same researchers in a different study found calcium citrate was better absorbed than calcium carbonate— but only when taken with meals.
"The general recommendation is that calcium be taken with meals, so the small difference between citrate and carbonate under fasting conditions is not pertinent," says a leader in calcium research, Dr. Robert Heaney, at the University of Nebraska.
In a 2007 study in the American Journal of Clinical Nutrition, researchers from the Division of Bone and Mineral Diseases at Washington University School of Medicine in St. Louis found calcium from dietary sources was better absorbed than supplemental calcium, possibly because of the vitamin D content in dairy sources.
This finding was not a big surprise since vitamin D has always been recognized to be necessary for efficient calcium absorption. For the postmenopausal set, calcium and vitamin D together have been shown to prevent bone loss and decrease bone breaks. And both nutrients influence those calcium-regulating hormones.
Inulin is increasingly being used to boost calcium absorption, especially in dairy foods. "Inulin has been shown to improve calcium absorption in some studies, though not in others," Heaney says. "The effect is relatively small, and whether it's worth the extra cost is a matter of judgment. The cheapest way to absorb more calcium is to take more calcium."
To add to the debate, a new calcium form, calcium formate, is being researched. A 2005 study comparing it to carbonate and citrate found it superior in terms of getting into the blood faster, lingering longer and, significantly, decreasing parathyroid hormone, which promotes bone breakdown. It has yet to make it into product formulations, it is indicative of the continuing research and development aimed at improving calcium content and bone health of consumers.
Todd Runestad is science editor of Functional Ingredients magazine.
Natural Foods Merchandiser volume XXVIII/number 6/p. 54