Filler or Nutrient? The Ash In Cat Food

ash in cat food

Looking down the list of ingredients in my cat’s food and seeing the word ‘ash’ made me think of debris from a volcanic eruption. Don’t panic, your cat isn’t feasting on anything of the sort. So, what is ash in cat food? Often mistaken as a filler in pet food, when fed to your cat correctly, ash has far more benefits to our feline friends. 

In this article, we’ll discuss:

  • What Is Ash
  • Why Is it Called Ash
  • Where Does Ash Come From
  • Benefits and Disadvantages
  • The Mythical Link Between Ash and Feline Lower Urinary Tract Disease (FLUTD)
  • How Much Is Too Much
  • Finally: Conclusion

What is Ash?

Many of us wrongly assume that ash is a filler used to bulk out bad-quality cat food. In reality, ash or crude ash is a collective name for zinc, potassium, magnesium, chloride, phosphorus, calcium, copper, manganese, sodium, selenium, iodine, and iron. 

Your cat’s next meal will contain some or all of these minerals. Ash can be beneficial or detrimental to your pet’s health, depending on their intake. It’s essential to check ash content so you can get the balance just right for your furry companion. So let’s talk ash!

Why Is It Called Ash?

If you were to incinerate your cat’s supper, all the proteins, fats and carbohydrates would burn away during incineration. You are left with the inorganic mineral content. This is exactly what they do in the laboratory. 

By taking a sample of the food and incinerating it, they can measure the ash content in your cat’s food. They can’t provide the value of each mineral when using this burning method, so they give it the collaborative name “ash.”

Where Does Ash Come From?

Ash comes from two main sources: meat products and mineral supplements. Meat products will often include bones, tendons, and cartilage. Pet food manufacturers need to be aware of the quality of meat proteins in their ingredients. 

Low-quality meat proteins have high bone content. This causes an increase in calcium which can cause problems for your pet.

Benefits and Disadvantages 

Ash doesn’t have any disadvantages when given correctly, but if a food has a high ash content, this often means more bone content.

More bone produces more calcium which can prevent the absorption of minerals needed for things like healthy coats and skin. It can also make nutrients difficult to digest. 

Taste can also be affected by high ash content. Believe it or not, nutrients don’t taste fantastic, and too much ash in your cat’s food can leave a bitter taste. Although I can’t say I’ve tried it myself.

This doesn’t mean our beloved companions don’t benefit from ash. They need the minerals contained in ash to promote healthy teeth and bones. Ash also contributes to well-balanced fluids, immunity, and healthy muscle and nerve function. Everything we’d want for ourselves from a multivitamin, our pet gets from ash in their food. 

The Mythical Link Between Ash and Feline Lower Urinary Tract Disease (FLUTD)

During the 1970s and 80s, veterinarians thought ash played a starring role in causing urine infections leading to FLUTD. Later they found that this is not the case. 

They now believe that some pet food formulas were causing a high alkaline pH in cats. These increased pH values can cause struvite urinary crystals to develop in the bladder or urinary tract. These crystals are made up of minerals in the urine and can cause blockages or irritation.

If your cat is prone to urine infections, your vet might recommend a high protein or low ash diet. This is because foods high in protein will produce acidic urine, which combats the alkaline. A low ash diet means a lower mineral intake which helps prevent urinary crystals from forming.

You will find that cats on a wet food diet tend to have fewer problems with urine infections than those predominantly on dry kibble. This could be because of a higher meat protein and moisture content in wet foods than in a dry diet containing a higher amount of vegetables and grain. 

Consequently, this can cause a higher alkaline pH in your cat’s urine due to a lack of natural proteins.

How Much is Too Much?

Cats require approximately two percent of ash in their diet. However, like always, too much of a good thing can be a bad thing. Excessive amounts of ash can prevent the absorption of other vital nutrients needed for that healthy balanced lifestyle.

The AAFCO has produced guidelines to advise you on the minimum mineral content your cat needs. However, there are no official guidelines for maximum ash content. 

Veterinarians and nutritionist experts at Nature’s Protection have suggested that anything higher than 10 percent should be considered excessive. This is because if ash exceeds 10 percent, it becomes more difficult to digest.

Cat foods containing a lot of ash are likely to have a high bone content and are potentially low in quality. High ash content can occur if more meat or poultry meal has been used to produce it. 

Low-quality meat and poultry meal often contain a lot of bone. This increases calcium which causes the ash content to rise, which can lead to some of the issues we spoke about before. These high ash foods don’t provide any benefits, and they’re the reason that ash gets mislabeled as a filler. 

Although some cat foods with high ash content can be low-quality and detrimental, others are designed for specific purposes. Additional minerals may need to be given to a cat with nutritional deficiencies such as anemia. An expert nutritionist will have produced these specialist foods so the healthy balance will be just right. 

So, as you can see, the ash content gives us a clue about the quality of our pet food, and as long as it’s not too high, it’s nothing to worry about.


So, now we’ve answered the question, what is ash in cat food? It’s safe to say that it’s beneficial to your cat in the right amounts. However, it can become a filler when used in the wrong way by pet food companies. 

All in all, ash is crucial in your cat’s diet for healthy body development and function. They would gain the nutrients ash contains in the wild by hunting and foraging, so why not supply them with these at home?

Olivia Davis

Olivia is the editor-in-chief at Cat Food Tip. She's in charge of making sure that every post is up to standards and contains accurate information that's comprehendable and fun for readers.

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