Brewer's Yeast for Cats

By Judy Wolfe

Although its use in pets has been controversial, brewer's yeast is a popular nutritional supplement for both cats and dogs. Brewer's yeast for supplements is grown on molasses and sugar beets. Medicinal herb expert C.J. Puotinen says S. cervisia yeast, a strain of which is used to make beer, is found in pet supplement form. It's far more nutritious than the by-product breweries sell after using yeast to ferment their beers.


The University of Maryland Medical Center says that brewer's yeast is an excellent source of both B vitamins and the minerals chromium. B vitamins play an essential role in the health of your cat's skin, coat and eyes. They facilitate fat, protein and carbohydrate metabolism to keep kitty's energy levels up, and support both his liver and nervous system. Diane Stein, in Natural Healing for Dogs and Cats, says that commercial cat food may be lacking in vitamin B1. Severe vitamin B1 deficiency can cause seizures, lack of motor coordination and even death. She also recommends chromium to regulate blood sugar in diabetic cats.

Brewer's Yeast and Fleas

Although some holistic vets, including Dr. Richard Pitcairn, recommend daily supplementation with brewer's yeast and garlic as a way to keep fleas from infesting your cat, a 1983 UC Davis study found that giving dogs 14g of brewer's yeast each day for 5 weeks neither repelled nor killed fleas.

Side Effects

Many cats are allergic to brewer's yeast. If your cat starts scratching or showing other signs of an allergic reaction, stop giving her not only the brewer's yeast but all yeast-containing products.

Kinds of Brewer's Yeast for Cats

Brewer's yeast for cats is manufactured as a liquid, in tablets and powder. Any of them can be mixed with your cat's food. C.J. Puotinin advises that if you want use brewer's yeast as a flea repellent, look for high sulfur content, which may be unpalatable for fleas. High-sulfur brewer's yeast is grown on molasses.

Brewer's Yeast Dosages

The Tree House Humane Society recommends a dose of 1 tsp. of brewer's yeast per day for your cat. If you're using a commercial tablet or liquid, follow the dosing instructions on the package.