Are Egg Shells Edible?

In this short article, we are going to provide an answer to the question, “Are eggshells edible?”, with an in-depth analysis of the benefits of using eggshells, the nutritional value of eggshells, and the risks of consuming eggshells.

Are eggshells edible?

Yes, eggshells are edible. Eggshells contain on average 90-95% of calcium carbonate crystals that have a great number of benefits for humans but it only depends upon the limit and way of consuming eggshells because this is what makes the difference (4).

Other than use in diet, eggshells also have plenty of uses rather than just being a waste. It plays its role as a good fertilizer as eggshells enrich the soil content as well as prove to be a good compost too. It can also work as fodder for chickens and birds.

Powdered eggshells are one of the most effective and direct sources of calcium. The right way of eggshell consumption can fulfill daily calcium requirements in the form of dietary supplements. The eggshells are also a rich source of calcium (98.2%). Magnesium and phosphorus are present in trace amounts, providing about 0.9% of each. A 2.7 g of eggshell powder can provide about 100% of the recommended dietary intake of calcium for adults. Some other microelements like boron, copper, iron, molybdenum, sulfur, silicon and zinc are also present in eggshells (1).

Approximately 2 million osteoporotic fractures occurred in theUnited States in 2005. The health burden of fractures is substantial in the older adult population. Twenty percent to 30% of patients die within 1 year of a hip fracture, with significantly higher mortality rates in men than women. Nearly 40% of persons who experience a fracture are unable to walk independently at 1 year, and 60%require assistance with at least 1 essential activity of daily living (2).

A proper way of using eggshells:

The size of the eggshell must be reduced to be absorbed by the body. Size-reduction can be made by mechanical processing of dry eggshell using a mixer mill, or converting dry eggshells into powder by using a rolling pin and sieve. It should be then treated with acidic solutions such as vinegar, lemon or orange juice to dissolve the eggshell. Sterilization is also necessary prior to its incorporation in food (1). 

The following procedure is used  to make sure eggs are safe for consumption

·         Wash the eggshells thoroughly and rinse them out so they are clean. After washing and rinsing, dry out the eggshells.

·         Once that is done, bake the dried eggshells for 10 minutes so their raw texture and taste can vanish.

·         Transform the baked eggshells into a fine powdery substance by either grinding, blending, or using a mortar and pestle.

·         This powdery substance is perfect for use in drinks, foods, and even a spoonful directly.

Benefits of eggshells:

It has been established that powdered eggshells in our diet prove to be the most effective source of pure calcium carbonate. Following are some of the benefits we can obtain from using powdered eggshells in our diet.

·         The high calcium content in the eggshells promotes good bone health. Though bones require a decent amount of calcium daily to nourish the bone tissue. The calcium present in eggshells not only gives the necessary nutrients to the bone cells but also promotes a healthy bone life.

. A prospective role of calcium in regulating body weight could be annotated by observations that a calcium rich diet during periods of high energy intake mitigated adipocyte lipid deposition and weight gain. This intracellular calcium would then in return, reduce the expression of fatty acid synthase (1).

·         Calcium carbonate also works as an antacid and helps in relieving digestive issues as well. Issues like heartburn, stomach ache, and incomplete digestion can also be treated and resolved through its consumption. Chewed calcium carbonate (CaCO3) rapidly neutralizes esophageal acid and may prevent reflux (9).

·         Eggshells play a vital role in improving bone strength especially in patients with osteoporosis. These patients can add powdered eggshells to their diet, as eggshells are high in calcium content and are known to improve bone mineral density which can be a monumental change.

·         Hyaluronic acid present in eggshells can be good for skin as it helps with retaining moisture in the skin and giving it a soft dewy look. Eggshell membranes are source of  hyaluronic acid, which  is a type of GAG that serves as a natural moisturizer and lubricant between epidermal cells to inhibit the production of matrix metalloproteinase and also promotes collagen synthesis, tissue repair, and hydration (8).

·         They may also help in the removal of toxic substances from the body. Powdered eggshells mixed in water aid in the removal of toxins from the blood.

·         Calcium is known to reduce the risk of colorectal cancer by binding to oncogenic bile acids and ionized fatty acids. This impaired the activity of these carcinogenic compounds to flourish in the mucosal layer of the colon (1).

Eggshells can be the most effective way of treating ulcers. Gastric ulcers can be cured by using powdered eggshells in a moderate amount.

·         Mineral content essential for dental health can also be fulfilled by eggshells. The remineralizing process requires a high amount of pure calcium carbonate which is readily provided and helps in curing cavities in an efficient way. Eggshell solution has a very high percentage of bioavailable calcium which plays an active role in remineralisation of enamel (3).

·         It also contains collagen and other structural proteins which play a vital role in providing elasticity to the skin (8).

·         The magnesium content in eggshells is also known to improve nerve and muscle function (1).

Nutritional Value of eggshells:

Following are the nutrients present in an eggshell;

·         Calcium carbonate

·         Magnesium

·         Protein

·         Phosphorus

·         Potassium

·         Glucosamine

·         Hyaluronic acid

Besides, eggshell membranes are an abundant raw material that are a novel source for naturally occurring bioactive compounds such as glucosamine, chondroitin sulfate, fibrous proteins such as collagen Type I, elastin, keratin and sulfur-rich proteins and other components including lysozyme, ovotransferrin, ovocalixin and desmosine and isodesmosine (8).

Harmful effects of consuming eggshell:

Even though there are numerous benefits of including eggshells in our diet, some harmful side effects of it exist too. A few are mentioned here;

·         If eggshells are not properly crushed into a refined powder, the crunchy chunks of the eggshell may get lodged in the throat which can lead to throat issues especially can cause thoracic cavity injury due to the sharp part of an eggshell. Hence, it is advised to properly grind the eggshells to form a refined powdery substance.

·         Unwashed and non-boiled eggshells may contain bacteria of various strains, the most common being Salmonella enteritidis. This bacterial strain may lead to food poisoning and other digestive disorders. Other potential pathogens are Avian Influenza virus, Campylobacter, Staphylococcus aureus, and Enterobacteriaceae (3).

·         As eggshells are rich in calcium carbonate so their excessive intake may cause toxicity in the blood leading to kidney stones which massively affects renal health (5).

·         It may also raise the risk of heart diseases to a marginally concerning level.

Conclusion:

In this short article, we have provided an answer to the question, “are eggshells edible?”, while providing an in-depth analysis on how to properly use eggshells, their benefits on our health, their nutritional value, and side effects of consuming eggshells.

References:

  1. Waheed, Marium, et al. Eggshell calcium: A cheap alternative to expensive supplements. Trend Food Sci Technol, 2019, 91, 219-230.
  2. Grossman, David C., et al. Vitamin D, calcium, or combined supplementation for the primary prevention of fractures in community-dwelling adults: US Preventive Services Task Force recommendation statement. Jama, 2018, 319, 1592-1599..
  3. Chakraborty, Sagarika, and Santa Datta De. Eggshell: an alternative, cheap, bioavailable source of calcium in human diet. Res. Rev. J. Dairy Sci. Technol, 2019, 8, 25-33.
  4. Hamilton, R. M. G. The microstructure of the hen’s egg shell-a short review. Food Structure, 1986, 5, 13.
  5. Bargagli, Matteo, et al. Calcium and Vitamin D Supplementation and Their Association with Kidney Stone Disease: A Narrative Review. Nutrients, 2021, 13, 4363.
  6. Ruff, Kevin J., et al. Eggshell membrane: a possible new natural therapeutic for joint and connective tissue disorders. Results from two open-label human clinical studies. Clin Interv Aging, 2009, 4, 235.
  7. Lonnerdal, Bo. Effects of milk and milk components on calcium, magnesium, and trace element absorption during infancy. Physiol Rev, 1997, 77, 643-669.
  8. Marimuthu, Chandramohan, et al. Application and merits of Eggshell Membrane in Cosmetics. Res J Topic Cosmetic Sci, 2020, 11, 24-31.
  9. Rodriguez-Stanley, Sheila, et al. Calcium carbonate antacids alter esophageal motility in heartburn sufferers. Digest dis sci, 2004, 49, 1862-1867.