Is There Any Harm in Eating Egg Shells?

December 21, 2025 •

4 min read

According to a 2018 study, chicken eggshells are a high-calcium food source, containing approximately 380 mg per gram, with high bioavailability, meaning the body can absorb it effectively. However, eating them requires specific preparation to avoid serious health risks, which include sharp fragments and bacterial contamination.

Quick Summary

Eating eggshells carries risks, including injury from sharp pieces and foodborne illness from bacteria like Salmonella. Proper sterilization and grinding into a fine powder are essential to mitigate these dangers and safely access their calcium content. While rich in calcium, consult a doctor before using eggshells as a supplement, especially if you have pre-existing conditions or are already on supplements.

Key Points

Physical Injury: Eating large, sharp pieces of eggshell can cause serious damage to your throat, esophagus, and other parts of the digestive system.
Bacterial Contamination: Raw eggshells can carry harmful bacteria like Salmonella, and must be sterilized through boiling before consumption to prevent food poisoning.
Rich in Calcium: Properly prepared eggshell powder is an excellent, low-cost source of highly bioavailable calcium, crucial for strong bones and teeth.
Homemade Supplement Potential: By boiling, drying, and grinding eggshells, you can create a safe, homemade supplement. However, proper technique is essential to avoid risks.
Risks of Overconsumption: Like any calcium supplement, excessive intake of eggshell powder can lead to hypercalcemia, kidney stones, and other health issues.
Consider Commercial Alternatives: For purity and convenience, commercially produced calcium supplements are a reliable, regulated option without the risk of heavy metal contamination found in some natural sources.
Joint Health: The eggshell membrane contains beneficial compounds like collagen and glucosamine, which may support joint health, though more research is needed.

Can Eating Egg Shells Cause Harm?

While some cultures and home remedies utilize eggshells for their high calcium content, simply chewing and swallowing shell fragments from an unwashed egg is dangerous. The two primary risks are physical injury from the shell's sharp texture and illness from bacterial contamination. Raw eggshells can harbor bacteria, most notably Salmonella enteritidis, which can cause severe food poisoning. Ingesting large, sharp pieces can lead to damage in the esophagus or other parts of the digestive tract.

Physical Dangers: Choking and Internal Damage

Large, unground pieces of eggshell can be a choking hazard for children and adults. Their brittle, sharp nature also means they can easily scratch or damage the delicate tissues of the throat, esophagus, and intestines as they pass through the digestive system. For this reason, proper preparation is not optional when consuming eggshells.

Bacterial Risks: Salmonella Contamination

Raw eggs and their shells can be contaminated with Salmonella, a bacterium that can cause severe gastrointestinal illness. This risk is why safe handling and cooking of eggs are emphasized. To make eggshells safe for consumption, they must be properly sterilized, which typically involves boiling for an adequate period. This heat treatment effectively kills any harmful pathogens on the surface.

Heavy Metal Concerns

Another potential risk of consuming natural calcium sources like eggshells is exposure to heavy metals. While the risk is generally considered low in eggshells compared to other sources like oyster shells, trace amounts of elements such as lead and mercury can be present. This is one reason why commercial calcium supplements are often preferred, as they are tested and regulated to ensure purity and safety.

The Benefits of Properly Prepared Eggshells

Despite the risks of eating them raw, eggshells can be a valuable dietary supplement when processed correctly. They are an extremely rich source of calcium, which is vital for bone health.

Bone Density and Osteoporosis Prevention

Eggshells are composed almost entirely of calcium carbonate, the same compound used in many commercial calcium supplements. Research suggests that calcium from eggshell powder may be more bioavailable than purified calcium carbonate, meaning the body can absorb it more effectively. Studies on postmenopausal women with osteoporosis have even shown improved bone mineral density with eggshell powder supplementation. This makes it a compelling, inexpensive alternative for those seeking to increase their calcium intake for bone health.

Joint Health Support

The thin membrane found between the egg white and the shell is rich in beneficial proteins like collagen, as well as glucosamine and chondroitin sulfate. While the amounts in homemade powder might be trace, supplements made from this membrane have shown promise in supporting joint health, though more research is needed. Many DIY recipes recommend keeping this membrane attached during processing.

How to Safely Prepare Eggshell Powder

Creating your own eggshell calcium powder requires careful attention to sanitation and processing to eliminate health risks.

Rinse Thoroughly: Wash the eggshells with water to remove any residual egg white or debris.
Boil for Sterilization: Place the shells in a pot of water and bring to a rolling boil for 10–15 minutes. This step is crucial for killing bacteria like Salmonella.
Dry Completely: Remove the boiled shells and let them dry overnight. For extra crispiness and to ensure all moisture is gone, bake the shells on a sheet tray at 250°F (120°C) for 15-20 minutes.
Grind into a Fine Powder: Use a spice grinder or a powerful blender to pulverize the dry shells into a very fine, flour-like powder. It is essential to achieve the finest consistency possible to avoid internal injury from sharp fragments.
Store Properly: Keep the finished powder in an airtight container in a cool, dry place. A small, dry scoop can help with measuring.

Potential Downsides and Considerations

While there are benefits, some downsides exist. The gritty texture can be unpleasant, even when finely ground. Overconsumption of calcium from any source can also lead to health problems, such as hypercalcemia, kidney stones, and potential heart issues. The optimal dosage of homemade eggshell powder is not standardized, making it easy to exceed recommended daily intake.

Comparison: Homemade Eggshell Powder vs. Commercial Calcium Supplements


Feature	Homemade Eggshell Powder	Commercial Calcium Supplements
Cost	Virtually free, using kitchen waste.	Can be expensive depending on the brand and quality.
Purity	Risk of heavy metal contamination and requires meticulous sterilization to be safe from bacteria.	Regulated and tested for contaminants, ensuring high purity.
Bioavailability	High, potentially better than some purified calcium forms due to natural components.	Varies by formulation; some chelated forms offer high bioavailability.
Trace Minerals	Contains naturally occurring minerals like strontium, magnesium, and fluoride.	Varies by brand; often contain synthetic forms or are fortified with other vitamins.
Convenience	Labor-intensive preparation process involving cleaning, sterilizing, and grinding.	Easy to take as capsules or tablets; no preparation needed beyond opening the bottle.
Dosage Control	Difficult to measure consistently; risk of overconsumption without careful measurement.	Standardized dosages on packaging allow for precise and controlled intake.

Conclusion

Eating raw or unprocessed eggshells poses clear and significant harm due to bacterial contamination and physical injury risks. However, when properly cleaned, sterilized, and ground into a fine powder, they transform into an inexpensive and effective source of highly bioavailable calcium. While homemade supplements offer a zero-waste and nutrient-rich option, they require diligent preparation to be safe. Commercial alternatives provide a more regulated and convenient choice, free from contamination concerns. Ultimately, for those considering using eggshells as a dietary supplement, consulting a healthcare professional is crucial to ensure proper dosage and to weigh the risks against the benefits based on individual health needs. This mindful approach ensures a potential health benefit without introducing unnecessary harm.

For more information on food safety best practices, visit the Food and Drug Administration (FDA) website.

Frequently Asked Questions

The biggest risk of eating raw eggshells is bacterial contamination, primarily with Salmonella enteritidis, which can cause severe food poisoning.

While eggshells and teeth both contain calcium carbonate, chewing unground eggshells is not recommended as it can be abrasive and potentially damage tooth enamel over time.

The safest way is to thoroughly wash, boil, and then bake the eggshells before grinding them into a very fine, flour-like powder to be mixed into food or beverages.

A single eggshell contains approximately 2.2 grams of calcium, which is more than the average daily requirement for most adults.

Yes, studies suggest that calcium from eggshell powder is highly bioavailable and may be absorbed more effectively than purified calcium carbonate supplements.

Eggshell powder may help increase bone mineral density in individuals with osteoporosis, but you should always consult a doctor before using it as a supplement.

Natural sources like eggshells can contain trace amounts of heavy metals like lead and mercury, though levels are typically low compared to other natural sources.