Consuming eggshells, often considered for use as a natural supplement, raises immediate questions about safety and potential benefit. The core question is whether eating eggshells presents a danger, or if they can be safely incorporated into a diet. The answer depends entirely on the preparation, as raw and unprocessed eggshells carry distinct and serious risks.
Immediate Safety Concerns
Consuming improperly prepared eggshells presents two major safety hazards: physical injury and microbial contamination. The hard, brittle shell fractures easily into sharp, jagged pieces. If swallowed, these fragments can cause abrasions, tears, or perforations to the delicate mucous membranes lining the digestive tract.
The second danger is the presence of harmful bacteria, most notably Salmonella. Eggshells are highly susceptible to contamination from fecal matter and environmental sources. The porous nature of the shell allows these pathogens to be present on the exterior and sometimes the interior.
Without a sterilization step, consuming raw eggshells carries a high risk of contracting a foodborne illness like Salmonellosis, which can cause severe symptoms such as fever, diarrhea, and abdominal cramps. This microbial risk is the primary reason why eating unsterilized eggshells is strongly advised against for all individuals.
The Nutritional Composition
Once safety concerns are addressed through proper processing, the nutritional profile of eggshells reveals their potential value. An eggshell is overwhelmingly composed of calcium carbonate, which makes up about 90 to 95% of its total dry weight. This makes eggshell powder an exceptionally concentrated source of elemental calcium.
A single medium-sized eggshell can contain approximately 2.2 grams of calcium, providing more than the average daily requirement for an adult. Beyond the high calcium content, eggshells also contain a variety of trace minerals, including phosphorus, magnesium, zinc, iron, and copper.
The immense concentration of calcium is the primary reason for considering eggshells as a supplement. These nutritional benefits are not accessible if the shell remains intact and unprocessed. The body cannot effectively absorb calcium from large, undigested fragments, meaning proper preparation is necessary to unlock this mineral density.
Preparation for Safe Consumption
To safely utilize eggshells as a supplement, a two-step preparation process eliminates both microbial and physical hazards. The first step is sterilization to kill bacteria like Salmonella present on the shell surface. This is achieved by boiling the cleaned shells in water for five to ten minutes, or by baking them in an oven at 200°F to 350°F for 10 to 20 minutes.
Following sterilization, the shells must be completely dried and then mechanically processed to remove the physical hazard of sharp edges. This involves grinding the shells into an extremely fine, powder-like consistency. A coffee grinder or high-powered blender is effective in pulverizing the shells until no sharp fragments remain. The resulting powder can then be stored in an airtight container.