Lately I have been grinding eggshells to a powder and using that as a calcium supplement. Apparently eggshell calcium is thought to be one of the best sources of biavailable calcium you can ingest. 

I first peel off the skin from the shells, set the shells aside, then boil them for at least 5 minutes. I try and and collect several shells over a couple of weeks before boiling. Then I dry them and refrigerate, and grind when I need them. 

I am just curious as to whether anyone else has tried this?

TTYL,

Marilyn

See:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15018022&dopt=Abstract

Eggshell calcium in the prevention and treatment of osteoporosis.

Rovensky J, Stancikova M, Masaryk P, Svik K, Istok R.

National Institute of Rheumatic Diseases, Piestany, Slovak Republic. [log in to unmask]

In this paper the most significant biological and clinical aspects of a biopreparation made of chicken eggshells are reviewed. Eggshell powder is a natural source of calcium and other elements (e.g. strontium and fluorine) which may have a positive effect on bone metabolism. Experimental and clinical studies performed to date have shown a number of positive properties of eggshell powder, such as antirachitic effects in rats and humans. A positive effect was observed on bone density in animal models of postmenopausal osteoporosis in ovariectomized female rats. In vitro eggshell powder stimulates chondrocyte differentiation and cartilage growth. Clinical studies in postmenopausal women and women with senile osteoporosis showed that eggshell powder reduces pain and osteoresorption and increases mobility and bone density or arrests its loss. The bioavailability of calcium from this source, as tested in piglets, was similar or better than that of food grade purified calcium carbonate. Clinical and experimental studies showed that eggshell powder has positive effects on bone and cartilage and that it is suitable in the prevention and treatment of osteoporosis.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=13129316&dopt=Abstract

Chicken eggshell matrix proteins enhance calcium transport in the human intestinal epithelial cells, Caco-2.

Daengprok W, Garnjanagoonchorn W, Naivikul O, Pornsinlpatip P, Issigonis K, Mine Y.

Department of Food Science and Technology, Faculty of Agro-Industry, Kasetsart University, Bangkok 10901, Thailand.

Chicken eggshell powder has been proposed as an attractive source of calcium for human health to increase bone mineral density in an elderly population with osteoporosis. However, factors affecting calcium transport of eggshell calcium have not yet been evaluated. Chicken eggshell contains about 1.0% (w/w) matrix proteins in addition to a major form of calcium carbonate (95%, w/w). In this study, we found that soluble eggshell matrix proteins remarkably enhance calcium transport using in vitro Caco-2 cell monolayers grown on a permeable support. The total calcium transport across Caco-2 monolayers showed an increase of 64% in the presence of 100 microg/well soluble eggshell matrix proteins. The active enhancer with a molecular mass of 21 kDa was isolated by reversed phase high-performance liquid chromatography and did not correspond to any previously identified protein. The N-terminal sequence was determined to be Met-Ala-Val-Pro-Gln-Thr-Met-Val-Gln. The possible mechanisms of eggshell matrix protein-mediated increase in calcium transport and the potential significance of eggshell calcium as a nutraceutical are discussed.