Eggshells have been used as a natural source of calcium, and there is scientific validation supporting their use in addressing calcium deficiency. Eggshells are composed of approximately 95% calcium carbonate, a form of calcium that is bioavailable when properly processed. Several studies have investigated the safety and efficacy of eggshell powder as a calcium supplement. For example, a study published in International Journal of Clinical Pharmacology Research (1999) found that eggshell powder supplementation in postmenopausal women improved bone mineral density comparably to standard calcium carbonate supplements. Additionally, eggshell powder contains other beneficial trace elements such as magnesium and strontium, which may contribute to bone health.

The preparation of eggshells is important for safety and absorption; eggshells must be thoroughly cleaned and heated or boiled to eliminate pathogens, and then ground into a fine powder. Studies have shown that eggshell calcium is well absorbed and utilized by the human body. However, clinical evidence is still limited, and most research consists of small-scale or preliminary trials rather than large, long-term studies. Despite this, the available scientific data does support the use of eggshell as a cost-effective and bioavailable calcium supplement, particularly in populations where access to commercial supplements is limited.