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Cracking Up: Discovery in Using Eggshells

In a former position, I helped dozens of teachers hatch hundreds of chicken eggs each year. Occasionally, teachers would ask me how to get rid of the shells. I always suggested composting. But then a teacher asked, “can you eat eggshells?” Thus began a healthy curiosity - what can I do with my eggshells beyond composting? Would I ever consider eating them?

Eggshell Discovery #1:

Consuming eggshells is not entirely uncommon. Commercially processed eggshell powder has been baked into goods to add calcium to diets in nutrient-deficient communities. However, it is important to remember that eggshells present a risk of salmonella. In one study in rural Sub‐Saharan Africa the recommended approach to processing the eggshells included 10 minutes of hard boiling, removing the shell, and baking for another 20 minutes.

Eggshell Discovery #2:

Animals eat eggshells. When chicks hatch, their first meal is the remaining albumen (egg whites) from the shell. These shells can then be crushed and fed to laying hens to add calcium to their diet, which makes the eggs stronger. Chickens aren’t the only animals that will consume eggshells, but just like people, bacterial infection is a concern. Before feeding eggshells to animals, they need to be heated, usually to boiling temperature, for 30 minutes.

Brown Eggs

Eggshell Discovery #3:

According to Illinois Extension ground eggshell powder is good for your garden. I’ve been known to put my eggshells in the oven while I’m baking something. This process kills bacteria and makes the shells easier to process into a powder with a mortar and pestle. But remember that crushed eggshells are not much better than doing nothing. Make sure you ground your shells into a fine powder.

If I ever need more calcium in my diet, I’ll explore how to process eggshells, but for now, I’ll add them to my compost or my house plants, and enjoy the dishes I make from eggs, like flan!

Recipe: Flan

Image of Flan


  • 1 ½ cup granulated sugar

  • 4 large eggs

  • 2 cups whole milk

  • 2 tsp. vanilla extract


  1. In a heavy pan (like enameled cast iron) heat over medium heat 1 cup of sugar until it melts into a thick dark caramel. Try not to stir, but check often to make sure the sugar isn’t burning.

  2. Preheat your oven to 300*F. Fill a deep pan with water and begin warming in the oven.

  3. Once the caramel is runny, cover the bottom of your 7-inch round baking pan or 6 ramekins with the caramel. Set your baking dish in the now warm water bath and set aside.

  4. Combine the remaining ½ cup of sugar and eggs and whip until creamy.

  5. Add milk and vanilla, mix until smooth.

  6. Fill up your 7-inch round baking pan or ramekins with the custard.

  7. Bake in the water bath for 40-60 minutes until the custard jiggles when you pull it out.

  8. Allow it to cool slightly on the counter.

  9. Cover with foil or a clean dishtowel and then transfer to the fridge for at least 6 hours.

  10. When ready to serve take a knife to loosen the custard from the side of the container and turn it over on a serving dish.

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