Calcium is the most commonly taken mineral supplement, and calcium supplements come in scores of different forms. But only one is actually a food extract and that is calcium hydroxyapatite. This is the form of calcium that naturally occurs in bone. Low temperature processing techniques are used to extract microcrystalline hydroxyapatite concentrate (MCHC) from raw bone?the best products utilize MCHC from free-range, pesticide-free New Zealand cattle. MCHC is a complex crystalline compound composed of calcium (about 24 percent), phosphorous, delicate organic factors (thus the importance of low-temperature processing), protein matrix and the full spectrum of minerals that naturally comprise healthy bone. Look for a calcium supplement in which the only source of calcium is MCHC. Many supplements say “MCHC” or “calcium hydroxyapatite” on the label, but when you read the ingredients carefully you discover that a secondary source of calcium, typically dicalcium phosphate?an inexpensive, poorly absorbed form of calcium?contributes an unstated percentage of the calcium to the supplement.
Many calcium formulas include magnesium; well-absorbed forms include magnesium aspartate, magnesium glycinate and magnesium oxide. Many other minerals may be complexed as aspartates or picolinates, which generally provide excellent absorption.