Calcium carbonate and magnesium oxide have both been shown to be poorly absorbed. Calcium carbonate is the cheapest calcium available in the marketplace today and is dependent on stomach acid for absorption. The problem is that as we age we tend to make less and less acid and therefore absorb less and less calcium from calcium carbonate. Some studies have even shown that you only absorb approximately 50 percent of the calcium from calcium carbonate.
Magnesium oxide is even worse, especially considering the very well done studies that show that you only absorb approximately 10 percent of the magnesium from magnesium oxide. Since the major concern for increased adverse health conditions while taking calcium supplements is the result of taking calcium supplements alone or unbalanced, it is critical to be sure that your calcium and magnesium supplements contain highly absorbable calcium and magnesium. We recommend taking Magnical-D because it is based on recent cutting-edge research and it contains the highest absorbable forms of both calcium and magnesium.