Calcium Supplements

by Christine M. Ruessheim

Calcium supplements come in several forms (calcium salts), but only part of the calcium salt is elemental calcium. It is important to know how much elemental calcium a supplement provides because all the dietary recommendations refer to elemental calcium. To calculate how much elemental calcium is in a supplement, multiply the total milligrams (mg) by the fraction of elemental calcium to get total mg of elemental calcium. See examples below:

Calcium carbonate: = 40% elemental calcium
Example: 500 mg calcium carbonate x 0.40 = 200 mg elemental calcium

Calcium citrate: = 21% elemental calcium
Example: 500 mg calcium citrate x 0.21 = 105 mg elemental calcium

Calcium lactate: = 13% elemental calcium
Example: 500 mg of calcium lactate x 0.13 = 65 mg elemental calcium

Calcium gluconate: = 9% elemental calcium
Example: 500 mg of calcium gluconate x 0.09 = 45 mg elemental calcium

Dicalcium phosphate: = 23% elemental calcium + 19% phosphorus*
Example: 500 mg of dicalcium phosphate x 0.23 =115 mg calcium + 95 mg phosphorus
*Helmut Meyer/Jürgen Zentek give different values: 21/16

Egg shells:  = 39% elemental calcium + traces of phosphorus and trace elements
Example: 500 mg of dried powdered eggshell = 195 mg elemental calcium

Bone meal: =  30% elemental calcium + 17% phosphorus
Example: 500 mg of bone meal x 0.30 = 150 mg elemental calcium + 85 mg phosphorus

Some other measures:

1 teaspoon of bone meal = 4 g
1 teaspoon of dicalcium phosphate = 4 g
1 teaspoon of calcium carbonate = 5 g
1 teaspoon of eggshell = 5 g
1 teaspoon of Kitty Bloom Kalac M34 (38-39%)= 5g
1 teaspoon of Animal Essentials Calcium Supplement (34%) = 3g

Mineral Content in Bones of Ostrich (Struthio camelus var. domesticus)

41,2% Calcium (36,3-45,7%)
16,8% Phosphorus (15,2-18,4%)
0,49% Magnesium (0,35-0,64%)
167 mg Zink (93-287 mg)
94 mg  Iron (42-195 mg)
8,5 mg Copper (3,3-14,9 mg)
8,3 mg Manganese (4,6-13,0 mg)
10,0 mg Lead (0,9-56,8 mg)
453 mg Fluoride (290-640 mg)
11,2 mg Aluminium (1,6-20,8 mg)

Mg values are per kg bone ash.

Reference: Bissinger Klaus, Dissertation, University of Giessen, 2000
"Quantitativer Nachweis wichtiger Mengen- und Spurenelemente in Serum, Leber, Knochen und Vollblut sowie einige andere Gewebeparameter und Daten von gesunden, südafrikanischen Farmstraussen (Struthio camelus var. domesticus) im Schlachtalter".

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