I'm aware of a product being sold on the Internet said to be a new type of calcium with a higher absorption rate. However, I have seen no scientific studies to support this claim or any of the others made for the product: that it works better to build bone density and thus lowers the risk of osteoporosis more effectively than other forms of calcium, and that it also works better than anything else for heel spurs, fibromyalgia and osteoarthritis.
The manufacturers of calcium aspartate anhydrous say it is better than coral calcium, a product I do not recommend. I've seen no scientific research supporting any of the many health claims made for coral calcium.
I do recommend calcium citrate, because it is more easily assimilated than other forms. Calcium carbonate is easier to find and less expensive but not as well absorbed. It is OK to use calcium supplements containing vitamin D. In fact, I recommend that all people take 2,000 IU of vitamin D to insure proper absorption and use of calcium (as well as to prevent multiple sclerosis and many forms of cancer). To prevent osteoporosis, adequate vitamin D intake may be even more important than calcium supplementation. The reason for taking magnesium with calcium (in a 1 to 2 ratio) is to counteract calcium's constipating effect.
Bear in mind that should a new and better form of calcium come along that has made it past rigorous scientific scrutiny, you'll read about it on this site and hear about it from the mainstream media. When checking out new products that sound too good to be true, look for some independent documentation. Are scientific studies cited by name on the Web site? Will you find those studies if you look them up in the medical literature? You can search the huge MEDLINE database of medical journals at http://www.ncbi.nlm.nih.gov/pubmed. If you don't find any relevant studies, there probably aren't any.
Andrew Weil, M.D.