About Eggshell Powder (ESP)
You can find commercially produced eggshell powder (ESP). Some pet food companies (even raw pet food companies) use ESP as a calcium source in their foods. However, there are several problems with commercially produced (not home-made) eggshell powder:
- it comes from chickens that were raised in a factory farmed setting and subjected to unhealthy, cruel and inhumane conditions;
- because of the way the birds are fed and kept, the eggshells may not be nutritionally equivalent to eggs that come from chickens raised on pasture or as pets in one’s backyard;
- the shells are most likely irradiated, which denatures the product. “Irradiation damages food by breaking up molecules and creating free radicals. The free radicals kill some bacteria, but they also bounce around in the food, damage vitamins and enzymes, and combine with existing chemicals (like pesticides) in the food to form new chemicals, called unique radiolytic products (URPs)”. Besides freezing, we are very concerned by the use of any modern food additives or “kill-step” process that alter the natural nutritional and beneficial qualities inherent in food. We find these techniques (HPP and irradiation are the most widely used) high-risk/dangerous and potentially damaging to health;
- they may be contaminated with arsenic and other heavy metals, or other potentially dangerous contaminants;
- they usually come from Chinese sources. Unfortunately, this presents a problem with knowing what might be in them and what to test for to ensure safety and purity, even when lab testing is done by the US re-seller/manufacturer.
Thankfully, making your own eggshell powder is really simple. Here’s how…
Start with Eggs: Pasture-Raised, Home-grown/Backyard or Certified Organic
Purchase eggs from chickens that were raised properly: either on pasture or from backyard, free-range chickens. If your eggs are unwashed (BEST!), you will want to gently rinse the eggs (before cracking them) with a soft brush using produce wash or castile soap. Rinse well to make sure they do not have fecal matter, dirt or feathers on them. You will want to collect at least a dozen eggs worth of shells before getting started. Store the shells in the freezer until you have enough of them to make powder.
Make Eggshell Powder (three easy steps!)
RINSE: Rinse the eggs well, but gently – rinse them three times with fresh water or run water over a pile of the shells in a colander. Do not remove the membrane; it is a healthy addition to the diet and is a powerful joint supplement.
If you are concerned about salmonella, you can also chose the additional step of boiling the eggshells in water for 10 minutes. This will eliminate the risk associated with bacterial contamination (please, keep in mind, this risk is mostly an issue for people and rarely a health risk to dogs/cats).
DRY: Next, dry the eggshells out completely. You will want to dry the eggshells out in an oven or on a sunny windowsill really well for a few reasons. The drier they are, the easier they are to grind and the safer they are to be stored on the shelf – moisture can lead to mold growth, which may be toxic or dangerous. The shells should be completely dry to the touch, brittle and quick to crumble.
- Bake in the oven at 250-350 degrees for 10-15 minutes.
- Place eggshells in an open, shallow dish in any south-facing full sun window. Leave for a week or more until totally dry.
- Place eggshells in a dehydrator and dehydrate until achieving a desired “bone dry” consistency
GRIND: Crumble the shells down a bit and then grind them in small batches in a coffee grinder, mortar & pestle, or food processor. You may need to run and pulse the grinder or food processor back and forth to get them ground up completely. An ideal consistency is that of baking powder, but if it’s a little bit coarser than this, that’s okay. You want them to be fully ground into a gritty powder at a minimum because the finer the grind, the better the calcium can be absorbed by the body. When done grinding, be sure to keep the lid on the grinder to allow the powder to settle first or you will open up a cloud of powder. If stored in a cool, dark, dry place, ESP will last for a year on the shelf.
Using Eggshell Powder
Eggshell powder is an excellent source of calcium for those that do not feed consumable whole or ground bones as a part of the daily diet or use a product that already includes enough calcium to balance the phosphorus in the meat, organs, produce and grains you are feeding. Note: Feeding dairy as part of the diet does not provide adequate dietary calcium for dogs or cats to balance their diet!!!
General Feeding Guidelines:
1 teaspoon of eggshell powder contains an average of 1800 mg of elemental calcium carbonate.
The consistency of your grind will slightly alter how much calcium is in a teaspoon (range is 1800-2200 mg/teaspoon). It is best to err on the side of a little extra calcium than to underfeed this essential and vital nutrient for dogs and cats.
We have some general feeding guidelines for the use of eggshell powder below. Different cuts of meat and different proteins will each have unique phosphorus levels, but this is a good general guideline that will provide your pet with an adequate amount of calcium in their diet.
Note: If you really want to get specific with your calculations, I LOVE the very awesome El-Sham’s online calculator tool to calculate perfect ca:ph in your pet’s food — it has been around for over a decade and it’s an oldie but goodie (highly recommended!!)
Weight of Meat | Ground Eggshell
¼ pound | 1/8 tsp
½ pound | 1/4 tsp
1 pound | 1/2 tsp
Links to Learn More
Catcentric (for felines)
Dogaware (for canines)
Eggshell Powder for Human Consumption – YES!
Here’s a site that shows you how to prepare calcium for people consumption from eggshell powder. Check out this blog post to learn about using eggshells as a calcium source, but also about other great uses around the home!
Originally written by Kasie Maxwell for SFRAW 2006; revised/updated 2017.