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WHAT IS ELEMENTAL CALCIUM?
  • Calcium is an chemical element like sodium, oxygen, or magnesium.
  • It cannot be broken down into any other forms.
  • So, it’s important to read the labels on any supplement that you take.

Elemental calcium is the key because it's the actual amount of calcium in the supplement.
​It's what your body absorbs for bone growth and other health benefits.
​
The label on calcium supplements is helpful in determining how much calcium is in one serving.
​As an example, calcium carbonate is 40 % elemental calcium, so 1,250 milligrams (mg) of calcium carbonate contains 500 mg of elemental calcium. Be sure to note the serving size (number of tablets) when determining how much calcium is in one serving
8 THINGS THAT YOU SHOULD KNOW ABOUT CALCIUM SUPPLEMENTS
1. BIODISPONIBILY
DIFFERENT TYPES OF CALCIUM SUPPLEMENTS
Several different kinds of calcium compounds are used in calcium supplements. Each compound contains varying amounts of the mineral calcium — referred to as elemental calcium. 
Common calcium supplements may be labeled as:
  • Calcium carbonate (40% elemental calcium)
  • Calcium citrate (20 % elemental calcium)
  • Calcium gluconate (9 % elemental calcium)
  • Calcium lactate (13 % elemental calcium)
Calcium in its pure form, easily join other chemical elements and together will form compounds, otherwise known as molecules.
Calcium phosphate, calcium lactate and calcium gluconate are not recommended because they have very small amounts of calcium.
Don't be fooled by ads for coral calcium promoting it as a cure for hundreds diseases including heart disease, cancer and diabetes. Coral calcium is merely calcium carbonate. In June 2003, the U.S. 
Federal Trade Commission charged marketers with making false claims about the product's health benefits.
https://www.ftc.gov/news-events/press-releases/2004/06/marketers-supreme-greens-and-coral-calcium-daily-come-under-fire​
2. cALCIUM CARBONATE
  • If the calcium combines with carbon, and oxygen than, the molecule will be CALCIUM CARBONATE (CaCO3).
  • So, the molecule known as calcium carbonate contains elemental calcium, elemental carbon, and elemental oxygen.
  • When calcium carbonate is digested, the calcium that is bound to carbon and oxygen breaks away to return to its elemental form. 
  • It is an alkaline-based compound found in rocks, limestone, shells of marine animals, pearls, eggshells and snails.
  • The percentage of elemental calcium in calcium carbonate that is available for our bodies to absorb is 40 %.
  • Using calcium carbonate as an example, for every tab that contains 1000 mg of calcium carbonate, 400 mg (the 40 %) of that tablet is elemental calcium and becomes available for absorption in the digestive system.
  • In case you were wondering what the other 60 % of the tablet is, remember that it is the other two elements, carbon and oxygen.
  • Is cheapest and therefore often a good first choice.
3. cALCIUM CITRATE
  • provides 20 % of the elemental calcium
  • the percentage of elemental calcium in calcium citrate that is available for our bodies to absorb is 20 %.
  • using calcium citrate as an example, for every tab that contains 1000 mg of calcium citrate, 200 mg (the 20 %) of that tablet is elemental calcium and becomes available for absorption in the digestive system.
  • has an acidic base (citric acid - C6H8O7).
  • this acidity requires less production of natural stomach acids, allowing this type of calcium to be better absorbed than the carbonate form.
  • as a result, has a better absorption than that from calcium carbonate.
4. CALCIUM GLUCONATE & CALCIUM LACTATE
CALCIUM GLUCONATE
  • a form of of calcium with very low levels of actual calcium concentration (9% elemental calcium)
  • you would need to take very large amounts of the supplement to reach calcium requirements
  • is manufactured by the neutralization of gluconic acid
CALCIUM LACTATE
  • is found in foods such as dairy products.
  • is the most commonly used antacid and is added to fruits to keep them firm and extend shelf life.
  • the percentage of elemental calcium in calcium carbonate that is available for our bodies to absorb is 13 %.
  • ssing calcium lactate as an example, for every tab that contains 1000 mg of calcium lactate, 130 mg (the 13 %) of that tablet is elemental calcium and becomes available for absorption in the digestive system. ​
5. IS YOUR CALCIUM SUPPLEMENT SCIENTIFICALLY-BASE ADVANCED FORMULA?
  • Deficiencies of calcium, magnesium, boron, and vitamin D can contribute to the development of osteoporosis, thinning of the bones that make them prone to fracture.
  • Magnesium is an essential mineral that accounts for about 0.05 percent of the body’s total weight.
  • Along with calcium, magnesium is an important component of strong, healthy bones.
  • Vitamin D enhances calcium absorption in the small intestine and calcium utilization in bone formation.
  • Vitamin D also influences the utilization of phosphorus, another mineral that is important for strong bones.
  • Vitamin K influences the level of osteocalcin in the bone-forming cells and thus the rate of mineralization of bone.
6. IS YOUR CALCIUM SUPPLEMENT CONTAMINATED?
  • Only 10% of the calcium supplements analyzed met the criteria of acceptable Pb levels (1.5 μg/daily dose) in supplements /consumer products set by the United States.
Calcium supplements: an additional source of lead contamination.
Rehman S1, Adnan M, Khalid N, Shaheen L.
http://www.ncbi.nlm.nih.gov/pubmed/20953844
  • 4 of 7 natural products had measurable lead content, 4 of the 14 refined products had similar lead content, despite increasingly stringent limits of lead exposure, many calcium supplement formulations contain lead and thereby may pose an easily avoidable public health concern
JAMA 2000 Sep 20;284(11):1425-9.
Lead content of calcium supplements.
Ross EA1, Szabo NJ, Tebbett IR.- http://www.ncbi.nlm.nih.gov/pubmed/10989406
  • Lead contamination is not restricted to bone-meal and dolomite; significant amounts of lead, and also aluminum, have been found in calcium carbonate supplements labeled "oyster shell" or "natural source."
Nutr Rev. 1994 Mar;52(3):95-7. 
​Safety of some calcium supplements questioned.
Whiting SJ1.- http://www.ncbi.nlm.nih.gov/pubmed/8015752
7. QUALITY AND COST – WHAT ARE YOU PAYING FOR?
  • Manufacturers are responsible for ensuring that supplements are safe and claims are truthful.
  • Some companies have their products independently tested by U.S. Pharmacopeia Convention (USP), ConsumerLabs.com (CL) or NSF International (NSF).
  • Supplements that bear the USP, CL or NSF abbreviation meet voluntary industry standards for quality, purity, potency, and tablet disintegration or dissolution. Different types of calcium supplements have different costs.
  • A USP (United States Pharmacopeia) symbol on the label means that the calcium supplement is free of lead and other metals. It also meets standards for quantity of elemental calcium in the tablet and how well it dissolves.
  • Ask the company for certifications!
8. OUR CRITERIA FOR CALCIUM SUPPLEMENTS
  • Science-based – complex calcium supplementation : a tablet should contain a mixt of calcium carbonate and calcium citrate, magnesium, vitamin D and eventually vitamin K
  • Don’t forget: Magnesium works with calcium in muscle contraction and relaxation (calcium-contraction, magnesium-relaxation)
  • The balance of bone-building nutrients is what truly matters. Too much calcium, or calcium without its other co-nutrients can be hazardous to your health, especially for your heart and arterial health
  • Following GMP (Good Manufacturing Practices) for pharmaceuticals is a big plus
  • Tested by independent laboratory ​
References:
Who should consider calcium supplements?
​http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/calcium-supplements/art-20047097?pg=2​
​Wikipedia 
https://en.wikipedia.org/wiki/Calcium_carbonate
https://en.wikipedia.org/wiki/Calcium_citrate
https://en.wikipedia.org/wiki/Calcium_gluconate