Ingredient file // Other
Montmorillonite Clay
A processing clay with oversold health claims
Montmorillonite is an absorbent mineral mined and milled for use in animal feed. It helps dry mixtures flow and serves as a binder. Dog studies involving related clays do not show that the amount in ordinary food treats diarrhea or detoxifies dogs.
Role in the food Does a job- What it is
- A mined, absorbent clay mineral used in feed mixtures as an anticaking agent and binder.
- Made from
- Mined clay deposits
- Main job
- Feed processing aid
- Typical amount
- Not published
- Watch for
- Supplier screening for contaminants
- Not the same as
- Bentonite
Our read // In our catalog
In 1 of every 20 foods we track
Share of foods that list it
5%
152 of the 3,105 foods with an ingredient list on file, from 7 brands. 85 dry dog food, 35 frozen dog food, 13 wet dog food.
Each square is 1% of the catalog
Where it sits on the label
Median position 11. In the top five of 4 foods, so it is usually a minor ingredient.
Above the salt
Listed before the salt in 69% of foods. In the rest it is under about 1% of the recipe.
Price per lb
Median of the cheapest bag price across 73 priced foods, 30% above the catalog. The price is the food's, not the ingredient's.
Who leans on it
53%
of the foods that list it are from Instinct. 7 brands use it in total.
What it is
How it is made
Montmorillonite occurs in bentonite deposits mined for several industries, including animal feed. Suppliers crush, dry and grind the extracted clay so manufacturers can add it as a powder.6
- 01 // Source Clay deposit Bentonite deposits contain montmorillonite alongside other minerals, with the mix varying by source.
- 02 // Process Mined and crushed The clay is extracted from the ground and broken into smaller pieces.
- 03 // Process Dried and ground Suppliers remove moisture and mill the clay into a powder for feed manufacture.
- 04 // Output Clay powder The finished powder is packaged and shipped to manufacturers for blending into feed.
What is in it
Composition, dry matter
51.8-69.4
% silica
The range measured in one sodium montmorillonite deposit. It describes the clay's makeup, not a useful silicon dose for a dog.
Why it is in the bag
A processing aid that helps bind the food
- Main nutrition
- Supporting nutrient
- Does a job
- Mostly filler
Makers add montmorillonite for technical reasons. Clay swells when wet and helps feed particles hold together, and California feed rules allow bentonite, a clay rich in montmorillonite, as a pelleting aid at no more than 2% of the total ration. EFSA found an anticaking effect in premixes and complementary feeds, but no evidence it lasts in finished complete food. Where it usually sits on labels, it likely adds too little to change the food's nutrition.4,6,7
-
01
Keeps premixes flowing
Absorbent clay reduces caking while dry ingredients are blended. EFSA found an effect in premixes and complementary feeds, but could not show that it persists in complete feed.4
-
02
Helps bind feed
Clay swells when moistened and helps feed particles hold together. Feed rules recognize bentonite, which commonly contains montmorillonite, as a pelleting aid.6,7
-
03
Uses a mined supply
Mining and milling supply clay powder for animal feed. Bentonite is also mined for absorbents, drilling mud and industrial binding, giving suppliers uses beyond pet food.6,9
How much A dog challenge tested 0.5% of a related clay; a typical amount of montmorillonite in dog food is not published.2
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.
-
Brands say
Clay in food firms a dog's loose stool
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
In an open-label trial involving 60 dogs, medicinal smectite shortened chemotherapy diarrhea to a median of 19.5 hours versus 53 hours. A separate trial tested a paste with several ingredients. Neither measured montmorillonite at its usual food dose.1,3
-
Brands say
Clay binds aflatoxin before a dog absorbs it
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
In a 6-dog crossover challenge, food coated with 0.5% of a related aluminosilicate clay reduced a urinary aflatoxin marker by 48.4%. That does not demonstrate the same effect for every montmorillonite source in ordinary food.2,6
-
Brands say
Prevents finished kibble from clumping
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
EFSA found anticaking effects in premixes at 20,000 mg/kg and complementary feeds at 10,000 mg/kg. It explicitly found no evidence that the effect persists at the lower concentrations reached in complete feed.4,10
-
Brands say
Removes bacteria and viruses from a dog
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
A brand says moistened clay grabs bacteria and viruses. In laboratory tests, some montmorillonite samples inhibited Staphylococcus aureus, while the tested samples did not inhibit E. coli. Those tests measured no virus removal or effect inside dogs.5,10
-
Brands say
Provides useful trace minerals for dogs
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
A brand promotes the clay's minerals. The measured dry clay is mostly mineral oxides, including 51.8 to 69.4% silicon dioxide in one deposit. Its composition does not show that dogs absorb a nutritionally useful amount from food.5,10
Straight answers
What owners ask
-
Q01
Is it just filler?
NoIt has a processing role as a binder and anticaking aid. Its presence does not make a food more nutritious, and tests have not shown that it keeps finished kibble from clumping.4,7
-
Q02
Will it detox my dog?
No proofA small dog challenge found less absorption of one fungal toxin with a related clay. It did not test everyday exposure, pathogens or broad detoxification. Judge those claims separately from the clay's processing use.2,10
-
Q03
Does it treat diarrhea?
Not in foodMedicinal smectite shortened chemotherapy diarrhea in one dog trial. Another trial used a paste containing montmorillonite, probiotics and fiber. Neither shows that the amount in ordinary dog food treats diarrhea.1,3
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
- Chicken Fat 34%
- Chicken 33%
- Carrots 32%
- Flaxseed 28%
- Chicken Meal 28%
- Apples 27%
- Peas 26%
- Sweet Potatoes 25%
- Beef 24%
- Turkey Meal 22%
- Natural Flavor 20%
- Butternut Squash 19%
On the shelf
Foods that list it
152 foods in our reviews list it. Here are some of them.
Show 56 more
Primal Freeze-Dried Raw Scoopable Pronto Dog Food Topper42.4% proteinOpen Farm Surf & Turf Raw Freeze-Dried Dog Food38.9% proteinOpen Farm Pasture-raised Lamb Raw Freeze-Dried Dog Food38.9% proteinOpen Farm Farmer’s Table Pork Raw Freeze-Dried Dog Food46.3% proteinInstinct FreshDried Meal Blends Chicken & Harvest Blend Freeze-Dried Dog Food35.1% proteinInstinct Original Bites for Dogs Pollock Recipe Grain-Free Freeze-Dried Dog Food41.5% proteinInstinct FreshDried Raw Meals for Puppies Chicken Recipe Grain-Free Freeze-Dried Dog Food40.4% proteinInstinct FreshDried Meal Blends Beef & Orchard Blend Freeze-Dried Dog Food36.2% proteinPrimal Raw Nuggets - Turkey & Sardine Recipe Frozen Dog Food56.5% proteinPrimal Raw Scoopable Pronto Puppy Frozen Dog Food48.0% proteinPrimal Raw Scoopable Pronto Puppy Freeze-Dried Dog Food41.3% proteinPrimal Raw Patties - Turkey & Sardine Recipe Frozen Dog Food56.5% proteinPrimal Canine Raw Nuggets - Venison Frozen Dog Food55.6% proteinPrimal Freeze-Dried Raw Nuggets Dog Food Topper44.6% proteinPrimal Kibble in the Raw Dry Dog Food27.2% proteinOpen Farm RawMix Wild Ocean Recipe Dry Dog Food34.4% proteinBlue Seal EnTrust Healthy Weight Formula Dry Dog Food25.8% proteinBlue Seal EnTrust Small Breed Formula Dry Dog Food27.0% proteinBlue Seal EnTrust Healthy Adult Formula - Pork & Barley Recipe Dry Dog Food27.0% proteinNature’s Logic Original Canine Can: Turkey Wet Dog Food39.3% proteinNature’s Logic Original Canine Can: Duck & Salmon Wet Dog Food39.3% proteinNature’s Logic Original Canine Can: Beef Wet Dog Food39.3% proteinBlue Seal EnTrust Healthy Senior Formula Dry Dog Food28.1% proteinBlue Seal EnTrust Sensitive Stomach & Skin Formula Dry Dog Food27.0% proteinBlue Seal EnTrust Healthy Adult Formula - Lamb & Rice Recipe Dry Dog Food24.7% proteinInstinct Original Food for Small Breed Dogs Real Chicken Recipe Grain-Free Wet Dog Food38.6% proteinNature’s Logic Original Canine Can: Venison Wet Dog Food39.3% proteinNature’s Logic Original Canine Can: Pork Wet Dog Food39.3% proteinNature’s Logic Original Canine Chicken Feast Wet Dog Food39.3% proteinInstinct Raw Boost RawBoost+ Mixers Multivitamin Recipe Dog Food Topper38.3% proteinInstinct Raw Boost RawBoost+ Shakers Grass-Fed Beef Recipe Grain-Free Dog Food Topper40.4% proteinInstinct Original Food Real Chicken Recipe Grain-Free Wet Dog Food43.2% proteinInstinct Original Food for Small Breed Dogs Real Beef Recipe Wet Dog Food38.6% proteinInstinct Raw Boost PeakBoost+ Kibble Real Beef Recipe Grain-Free Dry Dog Food37.8% proteinOpen Farm RawMix Grain-Free Chicken & Turkey Dry Dog Food33.3% proteinOpen Farm RawMix Grain-Free Whitefish Dry Dog Food33.3% proteinOpen Farm Ancient Grains RawMix Wild Ocean Fish & Ancient Grains Dry Dog Food34.4% proteinInstinct Raw Boost RawBoost+ Whole Grain Kibble Real Beef & Barley Recipe Dry Dog Food27.8% proteinInstinct Raw Boost PeakBoost+ Kibble Real Salmon Recipe Grain-Free Dry Dog Food37.8% proteinInstinct Raw Boost PeakBoost+ Kibble Real Chicken Recipe Grain-Free Dry Dog Food37.8% proteinOpen Farm Ancient Grains RawMix Open Prairie Recipe-Ancient Grain Dry Dog Food34.4% proteinOpen Farm Ancient Grains Front Range Ancient Grains for Dogs - RawMix Dry Dog Food32.2% proteinOpen Farm Front Range RawMix for Dogs - Grain-Free Dry Dog Food33.3% proteinNature’s Logic Original Pure Naturals Beef Recipe Dry Dog Food34.1% proteinNature’s Logic Original Pure Naturals Chicken Recipe Dry Dog Food38.5% proteinNature’s Logic Original Pure Naturals Sardine Recipe Dry Dog Food33.0% proteinNature’s Logic Original Canine Grain Free Dry Kibble: Beef Dry Dog Food33.0% proteinNature’s Logic Pure Naturals Grain-Free Chicken Recipe Dry Dog Food36.3% proteinBlue Seal Entrust Adult Chicken Meal & Barley Recipe Dry Dog Food29.2% proteinBlue Seal Entrust Large Breed Puppy Chicken Meal & Barley Recipe Dry Dog Food31.5% proteinInstinct Raw Longevity Patties Cage-Free Chicken Recipe for Adults Ages 7+ Frozen Dog Food37.5% proteinInstinct Raw Longevity Patties Cage-Free Chicken Recipe for Puppies Frozen Dog Food37.5% proteinInstinct Raw Longevity Patties Farm-Raised Rabbit Recipe Frozen Dog Food40.6% proteinInstinct Raw Longevity Patties Grass-Fed Lamb Recipe Frozen Dog Food40.0% proteinInstinct Raw Longevity Patties Cage-Free Chicken Recipe Frozen Dog Food40.0% proteinInstinct Raw Longevity Patties Grass-Fed Beef & Wild-Caught Cod Recipe Frozen Dog Food43.3% proteinOur read // On the bag
Read it as a processing aid
When montmorillonite appears well down the ingredient list, judge the food by the ingredients above it and its nutritional adequacy statement. The clay has a plausible manufacturing job. Give little weight to promises that it detoxifies your dog, treats diarrhea or supplies useful minerals.
Sources
What we read
Checked September 1, 2026.
- 1 Chemotherapy-induced diarrhoea in dogs and its management with smectite: Results of a monocentric open-label randomized clinical trial
- 2 Identification and reduction of urinary aflatoxin metabolites in dogs
- 3 Efficacy of an orally administered anti-diarrheal probiotic paste (Pro-Kolin Advanced) in dogs with acute diarrhea: A randomized, placebo-controlled, double-blinded clinical study
- 4 Safety and efficacy of montmorillonite-illite (FIMIX 1g557) for all animal species
- 5 In vitro antimicrobial activity of layered silicate materials
- 6 Safety and efficacy of bentonite as a feed additive for all animal species
- 7 Cal. Code Regs. Tit. 3, § 2805 - Technical Additives
- 8 Assessment of the feed additive consisting of bentonite (dioctahedral montmorillonite) as an anticaking agent for all animal species and as a substance for reduction of the contamination of feed by mycotoxins for pigs, poultry and ruminants for the renewal of its authorisation (BASF SE)
- 9 Clays Statistics and Information
- 10 Ingredient Spotlight: Montmorillonite Clay