Vegemite for Cats?? (Maybe not, but yeast can be very useful and tasty!)

Yeast in Your Cat’s Diet: What You Need to Know

If you’ve ever looked at the ingredient list on your cat’s food or supplements and spotted the word yeast, you might have wondered…why is yeast in there?

Certain types of yeast can be a great addition to your cat’s diet. They’re packed with nutrients like B vitamins, amino acids, and important minerals. Some even offer powerful digestive and immune system support.

TL; DR - Key Takeaways

• Yeast can be a nutritious and functional addition to your cat’s diet

• Some forms (like S. boulardii) may support digestive health

• Brewer’s and nutritional yeast can boost flavour and encourage fussy eaters

• Yeast won’t cause ear infections - those are caused by different yeast species

• Quality matters - choose trusted brands and consult your vet first

So, What is Yeast, Anyway?

Yeast are microscopic fungi. Unlike plants, they don’t photosynthesise, but they do have cell walls and a nucleus. In pet nutrition, you’ll mostly see two forms:

• Active yeast: live yeast cells, used as probiotics

• Inactive yeast: heat-treated (non-living), often used for nutrition and flavour

Let’s break down the common types of yeast in cat diets and how they might help.

Probiotic Yeast: Saccharomyces boulardii

This active yeast works a lot like a probiotic and is popular in supplements for both cats and dogs. It’s a specific strain of Saccharomyces cerevisiae, originally discovered on tropical fruit peels in the 1920s.

For cats, it may help:

• Support healthy digestion

• Improve symptoms of chronic diarrhoea or gut inflammation

• Boost gut-friendly healthy short-chain fatty acid (SCFA) production 

• Support antioxidant levels

• Even reduce stress!

It’s safe for most cats but should be used with caution in those with compromised intestinal tracts. 

Brewer’s Yeast & Nutritional Yeast (Inactive)

Brewer’s yeast (a by-product of beer making) and nutritional yeast (grown specifically for supplements) are both rich in protein and B-complex vitamins.

These types of yeast are:

• Highly palatable - many cats love the nutty, cheesy flavour

• Nutritious - a natural source of B vitamins, amino acids, and minerals

• Versatile - an appetite stimulating hack! They can be sprinkled as a meal topper to encourage fussy eaters

Nutritional yeast is often sold in flake or powder form. Just be mindful: it’s also high in phosphorus, which may not be ideal for cats with kidney issues.

Autolysed Yeast

This is yeast that’s digested, or broken down, by its own enzymes (sounds strange, but it’s useful!). It offers a mix of flavour and functional benefits, making it a great ingredient in complete cat foods.

Though not usually sold on its own, you might see it listed in ingredient labels for its flavour and digestibility-boosting properties.

Yeast Extract

Yeast extracts are rich in natural flavour compounds like glutamic acid and certain peptides. Think of them as taste boosters that make food more enticing.

These extracts:

• Improve the taste and aroma of food

• May support gut health by encouraging beneficial fermentation in the digestive tract

• Are used in small amounts in many premium cat foods

Yeast Cell Wall Extracts (Prebiotics)

Yeast cell walls contain MOS (mannan-oligosaccharides) and β-glucans, which are types of dietary fibre that help support gut health. These are considered prebiotics, meaning they help feed the good bacteria in your cat’s digestive system.

Benefits include:

• Boosting healthy gut bacteria

• Supporting immune function

• Binding harmful bacteria to help prevent infections

You’ll find these in some gastrointestinal support diets and supplements.

Yeast Fermentate (Postbiotics)

Yeast fermentates or "cultures" include bits of yeast cells, fermentation byproducts, and metabolites. These are also known as postbiotics, and they may offer unique health benefits thanks to their rich mix of bioactive compounds.

Some studies suggest they may help with cats with:

• Digestive function

• Immune support

• Overall wellbeing

Selenium Yeast

This type of yeast is grown in a selenium-rich environment and can be a more bioavailable way to add selenium to your cat’s diet.

Why does that matter?Selenium supports antioxidant enzymes, which help neutralise free radicals and support your cat’s immune system.

Selenium yeast is typically used in small amounts and is sometimes found in complete diets or targeted supplements.

FAQ: Will Yeast Cause Ear or Skin Infections?

Absolutely not! This is a common myth. The yeast that may cause ear infections in pets (like Malassezia) is completely different from the nutritional or probiotic yeasts added to cat foods and supplements. Giving yeast-based supplements will not cause or worsen skin or ear problems.

How Can I Add Yeast to My Cat’s Diet?

• Meal toppers: Try sprinkling a small amount of nutritional or Brewer’s yeast over your cat’s food to improve taste and nutrition

• Yeast-based supplements: Under your vet’s guidance, you might try a probiotic like S. boulardii if your cat has digestive issues

• Yeast extract: A tiny amount of low-sodium yeast spread (like marmite) can be added to meals for aroma and flavour – which is especially useful in senior cats or cats on restricted-protein diets

Always talk to your vet before starting any supplement, especially for cats with chronic health issues.

A Final Note on Yeast Quality

Not all yeast products are created equal. Because there's no standardised way to measure the active compounds in many yeast supplements, it’s important to choose high-quality products from trusted brands. This is especially true for S. boulardii and yeast cell wall extracts.

When in doubt, ask your vet and they can help guide you toward safe and effective options for your cat.

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