Montmorillonite Clay

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

1. 01 // Source Clay deposit Bentonite deposits contain montmorillonite alongside other minerals, with the mix varying by source.
2. 02 // Process Mined and crushed The clay is extracted from the ground and broken into smaller pieces.
3. 03 // Process Dried and ground Suppliers remove moisture and mill the clay into a powder for feed manufacture.
4. 04 // Output Clay powder The finished powder is packaged and shipped to manufacturers for blending into feed.

1. 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

2. 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

3. 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

1. Brands say

   Clay in food firms a dog's loose stool

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. 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

2. Brands say

   Clay binds aflatoxin before a dog absorbs it

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. 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

3. Brands say

   Prevents finished kibble from clumping

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. 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

4. Brands say

   Removes bacteria and viruses from a dog

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. 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

5. Brands say

   Provides useful trace minerals for dogs

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. 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