There have been studies that attempt to show egg shells can be a viable source of calcium. The egg shells are ingested in a powdered form, and prove a viable source of calcium for human consumption.
Chicken eggshell powder (ESP) might be an attractive source of Ca for human nutrition. To study its nutritional value, we analyzed minerals, amino acids, and hormones in commercially available Slovakian ESP.
Therefore, ESP seems to have a beneﬁcial composition
with about 39% of elemental Ca, relevant amounts of Sr,
and low levels of Al, Pb, Cd and Hg. It may be used as
a Ca source in human nutrition.
—Mineral, amino acid, and hormonal composition of chicken eggshell powder and the evaluation of its use in human nutrition.
The present study indicates that healthy late post-menopausal women with an adequate Ca intake at baseline may increase BMD of the hip within 12 months following supplementation with the chicken eggshell powder-enriched supplement.
—Positive effects of a chicken eggshell powder-enriched vitamin–mineral supplement on femoral neck bone mineral density in healthy late post-menopausal Dutch women.
Powdered chicken eggshells might be an interesting and widely available source of calcium. In two studies using piglets we determined the digestibility of calcium from different diets.
Our conclusion is that eggshell powder is, in the case of casein-based diets, as good a source of calcium as CaCO3 and, in the case of soya protein-based diets, better than CaCO3 for growing piglets. As the piglet model is considered to be representative for humans, chicken eggshell powder is also a promising source of calcium for human nutrition.
—Eggshell powder, a comparable or better source of calcium than purified calcium carbonate: piglet studies.