Hey Christinam,
I think calcium in decently high amounts (1000-1500mg daily) is important. I know many people disagree with this. But many papers suggest how important it is to balance calcium with phosphorus. Since phosphorus is high in grains and beans (phosphorus from phytates) and from meats and eggs (and dairy), most American diets could do well to add calcium.
http://www.ncbi.nlm.nih.gov/pubmed/19781123
http://www.ncbi.nlm.nih.gov/pubmed/17903344
http://www.ncbi.nlm.nih.gov/pubmed/16925861
I can’t find it now, but I have somewhere an old paper paper showing how dietary Calcium:Phosphorus ratio impacts metabolism greatly. The liver turns thyroid hormone T4 into t3 (activated thyroid hormone) when times are good, and deactivates T4 into reverse t3 (rt3) when times are bad. t3 speeds up metabolism, while rt3 slows it down. The study shows how, as long as the calcium:phoshorus ratio is >1.0, the liver increases T4 to t3 conversion, but when dietary calcium drops below dietary absorbable phosphorus, then the liver slows T4 to t3 conversion and increase rt3 creation.
Of course, Danny Roddy has written about this a lot. I’m not sure about all his conclusions, but I agree calcium is important.
There are many sources of calcium. Calcium Carbonate is the most common supplement and Danny Roddy, for instance, prefers this via egg shells. I am not a fan. This form of calcium is somewhat alkaline and can buffer (reduce) stomach acid which is bad news for somewhat already having issues. Tums, an ‘antacid’, is calcium carbonate.
The more soluble the calcium is–up to a point–the better the absorption. Calcium dissolves well in organic acids, so calcium citrate (from citric acid) and malate (from malic acid) absorbs well. These forms of calcium are on par with dairy calcium for absorption. Calcium Citrate Malate (CCM, a patented combo calcium salt) absorbs perhaps a little better than diary calcium. Dissolving eggshells (calcium carbonate) into tomato juice or orange juice (for citric acid) should theoretically yield calcium citrate with released CO2 gas. I’ve tried this: it’s kind of like a tomato fizzy or orange fizzy.
But calcium citrate supplements are likely easier. Trouble is, I have only found one without weird fillers or other stuff.
http://www.gnc.com/GNC-Calcium-Citrate-1000-mg/product.jsp?productId=16513286
GNC’s calcium citrate only has cellulose tablets, which I have done fine with.
Calcium hydroxyapatite (a source similar to bones) dissolves ok. You can find that all over. Here is one:
http://www.iherb.com/Now-Foods-Calcium-Hydroxyapatite-Caps-250-mg-120-Capsules/459
I prefer calcium citrate to this, since hydroxyapatite has a decent amount of phosphorus. Since balancing calcium and phosphorus is part of the point of supplementing calcium in the first place, I don’t like the hydroxyapatite version for meat and grain eaters.
Those are my thoughts.