The Ingredients in Cat Food

Unraveling the Mystery of Cat Food Ingredients

Photo of Person Opening a Can of FancyFeast Cat Food

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Learning to read cat food labels can be a daunting task, especially with all those mysterious ingredients. For the health of your cat, you want to choose a cat food that is good for them and provides a well-balanced diet for their needs. By understanding what you're reading on the label, you will be better equipped to make educated food choices that may impact the longevity and vitality of your cat.

Deciphering the Ingredient List

The ingredients are listed in order by weight. Ideally, in a regular maintenance diet, the protein source should be the first ingredient listed on a bag of dry cat food. This should be followed by secondary protein sources. After that, you can expect to see carbohydrate fillers, oils or fats, preservatives, added vitamins, and minerals, as well as taurine (an amino acid that cats need to survive).

It can be surprising to realize that many of the popular "premium" cat foods do not follow this ideal formula. For example, one brand of chicken and rice formula lists (in order) chicken, brewers rice, corn gluten meal, poultry by-product meal, wheat flour, beef tallow preserved with mixed tocopherols (source of Vitamin E), and whole-grain corn. Following that are other meat products, preservatives, vitamins, and minerals. Compared to other food on the market, this one might actually qualify as "medium-to-good" quality—hardly premium or "the best."

The Association of American Feed Control Officials (AAFCO) sets the definitions for animal food ingredients. A cat food manufacturer may not list an ingredient unless it fulfills the AAFCO definition. As an informed cat owner, you'll want to know what all of these complex food ingredients actually mean and how they play a role in your cat's nutrition.

Meat Products

Protein provides amino acids that help a pet build and maintain its muscles, bones, blood, organs, immune system, and hair and nails. There are many combinations of protein sources that deliver a balanced amino acid profile. 

  • Chicken: The AAFCO defines "chicken" as the clean combination of flesh and skin with or without accompanying bone. It must be derived from the parts or whole carcasses of chicken or a combination thereof, exclusive of feathers, heads, feet, and entrails. This is a product you would expect to find in premium-quality cat food. Keep in mind, though, that the amount of bone and/or skin may play a part in the quality of the protein.
  • Poultry by-product meal: This is defined as ground, rendered, and clean parts of the carcass of slaughtered poultry. It includes things such as necks, feet, undeveloped eggs, and intestines. The meal should be exclusive of feathers, except in such amounts as might occur unavoidably in good processing practices. While it is true that cats do eat those parts of poultry in their natural or wild state, the "rendered" part is not natural. If you want to make the healthiest choice for your cat, then by-product meal should not be the first ingredient.
  • Beef tallow: This is obtained from the tissue of cattle during the commercial process of rendering. Beef tallow is an inferior source of fat for cat food because it is saturated fat. It is primarily added to give the food flavor.
  • Fish meal: This ingredient is the clean, dried, and ground tissue of undecomposed whole fish or fish cuttings. A portion of the oil may or may not be extracted and it must contain no more than 10 percent moisture. If the fish meal contains more than 3 percent salt, the amount of salt must constitute a part of the product name (and it may not exceed 7 percent). The salt mentioned here is the ingredient you have to watch for.
  • Egg product: Eggs may be dehydrated, liquid, or frozen, and must be labeled according to the USDA regulations governing eggs. They must be free of shells.


Carbohydrates are an important source of energy for your cat, supplying the building blocks (glucose) for cellular energy. They also provide the fiber in pet diets which is important for gut health. Some foods may contain empty fillers in which most of the nutrition has been leached out by other processes. Usually, when an ingredient list mentions a whole grain, it is a better choice for your pet.

  • Brewers rice: This ingredient refers to the rice leftover from making beer. It is the dried, extracted residue of rice resulting from the manufacture of wort (the liquid portion of malted grain). Brewers rice may contain pulverized, dried, and spent hops in an amount not to exceed 3 percent. It stands to reason that this rice "residue" may not be the same quality of carbohydrate as whole grain rice.
  • Corn gluten meal: This is the dried residue from corn after the removal of a larger part of the starch and germ and the separation of the bran. It is what is left over after making corn-based products, such as corn starch or syrup, among others. Corn is a popular filler because it is inexpensive. It is also one of the products responsible for allergies in cats. If you have to choose a cat food with corn as an ingredient, you would be better off with "cornmeal" because it also includes the germ and is not just a residue.
  • Wheat flour: The AAFCO defines this ingredient as wheat flour with fine particles of wheat bran, wheat germ, and the offal from the "tail of the mill." This product must be obtained in the usual process of commercial milling and must not contain more than 1 1/2 percent crude fiber.

Preservatives and Supplements

While vitamins and minerals are added in very small amounts, they account for close to half of the ingredients in pet food and make up the longest part of a label's ingredient list. To be listed as "complete and balanced" cat food, the AAFCO lists 25 essential vitamins and minerals.

  • Mixed-tocopherols: Most premium foods use mixed tocopherols, which are listed as a source of Vitamin E. It also contains Vitamin A as well as preservatives. These are not quite as effective as the old chemical preservatives BHA and BTA, so always check the maximum shelf life date on the label.
  • Sodium caseinate: Casein is a milk product similar to whey. The sodium makes it a salty component used for flavoring and preservation.
  • Potassium chloride: This is a potassium salt of hydrochloric acid. Potassium is essential to all species for heart and nerve function. However, in cat food, it is used as a salty component that adds flavor and acts as a preservative.
  • Phosphoric acid: A mineral supplement consisting of 32 percent phosphorus, this is another additive that helps acidify the food to enable the cat to maintain a proper urinary pH.
  • Brewers dried yeast: Brewers dried yeast must come from the brewing of beer or ale for human consumption. Having been sterilized and with no leavening power, it is an inactive yeast composed of the single-celled organism Saccharomyces cerevisiae. Brewers dried yeast is a protein source rich in amino acids and B vitamins. Amino acids help a pet build and maintain muscles, bones, blood, organs, immune system, and coat and nails. Without the proper levels of essential amino acids, the synthesis of protein is impacted. In addition, B vitamins support brain function, muscle strength, red blood cell production, and digestion. While brewers dried yeast may taste bitter to humans, dogs and cats find it rather tasty. A probiotic, it can also help reduce stress and sickness as well as prevent fleas.
  • Natural flavors: As defined by the AAFCO, this is a feed or ingredient derived solely from plant, animal, or mined sources. It may either be in its unprocessed state or have been subject to physical processing, heat processing, rendering, purification, extraction, hydrolysis, enzymolysis, or fermentation. It may not be produced by any chemically synthetic process and cannot contain any chemically synthetic additives or processing aids except in amounts as might occur unavoidably in good manufacturing practices. This "ingredient" is so vague and unclear that it might as well be left off since you have no idea what the actual ingredient is.
  • Remaining ingredients: Vitamins and minerals bring up the tail end of the ingredients list. They are fairly common to all cat foods and include an array of hard to pronounce names. For instance, you will find calcium carbonate, tetrasodium pyrophosphate, L-Lysine monohydrochloride, salt, choline chloride, vitamin supplements (E, A, B-12, D-3), taurine, zinc sulfate, ferrous sulfate, ascorbic acid (source of Vitamin C), L-Alanine, riboflavin supplement, niacin, calcium pantothenate, manganese sulfate, biotin, thiamine mononitrate, folic acid, copper sulfate, pyridoxine hydrochloride, citric acid, menadione sodium bisulfite complex (source of Vitamin K activity), calcium iodate, and sodium selenite A-4623.