Ingredient file // Vitamin or mineral
Eggshell Powder
A real calcium source, mostly for homemade diets
Eggshell powder is ground, heat-treated chicken eggshell, and nearly all of it is calcium carbonate. It gives a dog calcium and almost nothing else, which matters in a meat-heavy recipe and adds nothing useful on top of a complete food.
- What it is
- Chicken eggshells, cleaned, heat-treated and ground into a fine powder that is mostly calcium carbonate.
- Made from
- Shells from egg-breaking plants and hatcheries
- Main job
- Calcium source
- Typical amount
- Not published; dog biscuits took up to 2 g/100 g flour
- Watch for
- Extra calcium for large breed puppies
- Not the same as
- Eggshell membrane
Our read // In our catalog
In 1 of every 384 foods we track
Share of foods that list it
0%
8 of the 3,068 foods with an ingredient list on file, from 1 brand. All dog food topper.
Each square is 1% of the catalog
Where it sits on the label
Median position 6.5. In the top five of 2 foods, so it is usually a supporting ingredient.
Who leans on it
100%
of the foods that list it are from Grandma Lucy's. 1 brand use it in total.
What it is
How it is made
Plants that break eggs for liquid and dried egg, and hatcheries, leave shells behind in bulk. Most go to fertilizer, feed or the dump. A cleaned, heated and ground share becomes calcium powder.1,2,4
- 01 // Source Spent eggshells Shells from plants that break eggs for liquid or powdered egg, and from hatcheries.
- 02 // Process Washed and sterilized Fresh shells carried Salmonella in one study. 121 °C for 15 minutes, or 60 minutes in 95 °C water, cleared it.
- 03 // Process Dried Hot air at 200 °C for 20 minutes made the powder release its calcium more readily.
- 04 // Process Ground Milled fine. Sterilized, ground shell is a highly available calcium source for animal feed.
- 05 // Output Eggshell powder A dry powder of about 39% calcium, with very low lead, aluminum, cadmium and mercury in tested samples.
What is in it
Composition, dry matter
37
% calcium
Average calcium in dried eggshell, with almost no phosphorus beside it. That makes it a calcium supplement and nothing else.
Why it is in the bag
What the manufacturer gets
-
01
Supplies calcium
Dried shell runs about 37% calcium with almost no phosphorus, so a small amount balances the calcium in a meat-based topper or home recipe.1
-
02
A label-friendly limestone
Eggshell is 94 to 97% calcium carbonate, the same compound as limestone, but it reads better on a bag. In mink it replaced limestone with no loss of digestibility.3,5
-
03
Waste turned into stock
About 26% of eggshell waste is simply dumped. Sterilized and ground, it becomes a mineral a processor can sell instead of a disposal cost.4
How much A 2023 dog biscuit study found the dough took up to 2 g eggshell powder per 100 g flour, giving biscuits about 507 mg calcium per 100 g.4
Our read // The claims
What the evidence supports
Strong: controlled studies in dogs agree. Some: small or mixed dog data. Thin: mechanism or lab work only. None: nothing, or the evidence points the other way.
-
Owners say
Eggshell is a real, natural calcium source
Evidence
- Strong
- Some
- Thin
- None
Plain arithmetic: samples ran 32 to 39% calcium on a dry basis, and a 2000 analysis found 401 mg per gram. It supplies calcium only. Phosphorus is a trace, about 1.6 g per kg.1,2
-
Brands say
Purer than limestone or oyster shell calcium
Evidence
- Strong
- Some
- Thin
- None
One analysis of 5 eggshell powders found very low lead, aluminum, cadmium and mercury, while refined calcium carbonate held more cadmium and oyster shell more aluminum and cadmium. A handful of samples is not a guarantee for every batch.2
-
Brands say
Eggshell calcium absorbs better than calcium carbonate
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
Eggshell is 94 to 97% calcium carbonate itself. In a mink trial, calcium digestibility did not differ significantly from limestone, showing only a trend (P < 0.06). No dog trial exists, so the claim rests on a nonsignificant result.3,5
-
Brands say
Eggshell supports your dog's joints
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
The dog trial behind this tested eggshell membrane, not powder: 51 dogs for 6 weeks, run partly by sponsor employees. The powder is mostly mineral with about 4% organic matter, and no trial tests it for joints.3,6
-
Owners say
Dogs on kibble need extra calcium
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
Complete foods are already formulated for calcium. Excess calcium harmed growing Great Danes, and dogs heading for 30 kg or more are most vulnerable. A veterinary nutritionist advises keeping calcium supplements away from large breed puppies.7,8
Straight answers
What owners ask
-
Q01
Is it just filler?
No, it's calciumIt adds almost no calories or protein. It is there for one nutrient, calcium, at about 37% of its weight. Filler would have no job; this has one.1
-
Q02
Should I sprinkle it on kibble?
NoA complete kibble already meets calcium needs, and eggshell brings calcium with almost no phosphorus. Use it only in a balanced homemade recipe that calls for it, not as an extra.1,8
-
Q03
Is it the same as eggshell membrane?
NoThe membrane is the thin protein layer inside the shell, sold on its own as a joint supplement. Eggshell powder is the hard mineral part, 94 to 97% calcium carbonate.3,6
-
Q04
Can raw shells carry Salmonella?
Yes, unheatedFresh shells in one study carried Salmonella and about 33 million bacteria per gram. Heat treatment took Salmonella to undetectable, which is why feed-grade shell is sterilized before use.1,4
Who uses it
Brands, best sellers and the company it keeps
Top brands, by foods that list it
Usually listed with, share of the foods that list it
- Pumpkin 88%
- Flax 63%
- Ginger 50%
- Turmeric 50%
- Potato Flour 38%
- Organic Apple 38%
- Carrots 38%
- Coconut 38%
- Oat Flour 25%
- Chicken Bone Broth 25%
- Beef Bone Broth 25%
- Oats 25%
On the shelf
Foods that list it
8 foods in our reviews list it. Here are some of them.
Show 6 more
Grandma Lucy’s Meal Prep Chicken Taproom Ale Dog Food Topper21.9% proteinGrandma Lucy’s Meal Prep Ranch Dog Food Topper20.2% proteinGrandma Lucy’s Meal Prep BBQ Rub Dog Food Topper12.3% proteinGrandma Lucy’s Meal Prep Coconut Cold Brew Dog Food Topper30.3% proteinGrandma Lucy’s Meal Prep Banana Flax Overnight Oats Dog Food Topper18.2% proteinGrandma Lucy’s Meal Prep Blueberry Pumpkin Chia Seed Pudding Dog Food Topper17.8% proteinOur read // On the bag
Use it to balance recipes, not to boost kibble
In a topper or fresh food, eggshell powder near the end of the list is the calcium source, doing a needed job in a meat-heavy recipe. Do not add it to a complete kibble yourself, and keep it away from large breed puppies unless a veterinary nutritionist built the recipe.
Sources
What we read
Checked October 1, 2026.
- 1 Eggshells
- 2 Mineral, amino acid, and hormonal composition of chicken eggshell powder and the evaluation of its use in human nutrition
- 3 State-of-the-Art of Eggshell Waste in Materials Science: Recent Advances in Catalysis, Pharmaceutical Applications, and Mechanochemistry
- 4 Modified eggshell powder using thermal treatment and its application in Ca-fortified dog biscuits
- 5 Eggshell as a calcium source replacing limestone meal in mink (Neovison vison) diets
- 6 Effectiveness of NEM brand eggshell membrane in the treatment of suboptimal joint function in dogs: a multicenter, randomized, double-blind, placebo-controlled study
- 7 Factors that modify the effect of excess calcium on skeletal development in puppies
- 8 Feeding large breed puppies