Re: Rheumatoid Arthritis and Osteoporosis Treatment

Calcium malate (CCM) definitely has superior absorption although some research suggests that calcium bisglycinate and calcium formate have even higher absorption rates.

Please link this research.  Not sales sites, not vague references but links to the actual research.  I did some searches on Medline and a few other sources and could not find any studies verifying the claim that calcium bisglycinate is better absorbed.

I did find a study discussing the absorption of calcium formate, which was higher.  Although, other factors have to be kept in mind such as the fact that calcium formate contains less calcium than calcium carbonate, but more than calcium citrate.  The calcium carbonate used in the test contained 40% calcium.  The calcium formate had 30.8% calcium and the calcium citrate 24.1% calcium.  All the calcium used in the test were tablets from commercial manufacturers with different binders, which again will affect absorbability.  Test subjects were given 2 tablets calcium carbonate, 6 tablets of calcium formate or 6 tablets of calcium citrate each to equal 1200mg calcium.  Another big variable though is the amount of not only stomach acid present but also the amount of flora since these also affect the rate of absorption of calcium compounds.  There are other factors still such as the presence of vitamin D, silica or some food acids that help in the absorption of calcium or the presence of compounds such as proteins, phytates or oxalates that block the absorption of calcium.

These forms of calcium are found in leafy green vegetables and some food based supplements. Absorption rates are as follows:

• Calcium Citrate/Malate (CCM): 40%
  
• Calcium Carbonate: 26%
• Calcium Citrate: 22%

Again, there are many variables so it is impossible to truly calculate actual calcium absorption rates.

Absorption rates for calcium carbonate and calcium citrate are similar if taken with meals-while calcium lactate (from cow’s milk)

But protein in cow's milk inhibits calcium absorption, which is one of the main reasons cow's milk is such a poor dietary source of calcium.

and calcium gluconate (highly promoted in liquid formulation) have solubility less than calcium citrate.

Solubility is a different factor than absorbability.

There are several reasons I prefer the malates and citrates.  First of all they are well absorbed even if there is a lack of stomach acidity.  The malic acid and citric acid these forms are bound to are also key components of the cellular production of ATP.  And these acids can provide other benefits such as dissolving some types of kidney stones.