TL;DR

Many common cat food ingredients, from artificial preservatives like BHA and ethoxyquin to unnamed meat by-products and grain fillers, offer no nutritional value to cats and may cause real harm over time. Australian cat owners face an extra challenge: pet food regulation here is voluntary, not mandatory, and sulphite preservatives in local pet meats have caused fatal thiamine deficiency in cats. This glossary covers every ingredient worth avoiding, explains how to spot them on labels, and outlines what to look for instead.

Cats are obligate carnivores. Their bodies are built to process meat, not corn starch, artificial dyes, or rendered mystery fats. Yet many commercial cat foods read more like a processed snack ingredient panel than anything a carnivore should eat.

The problem is worse in Australia than most cat owners realise. Unlike the US or EU, Australia has no mandatory pet food safety laws. The Australian Standard AS 5812 is voluntary. Manufacturers are urged to comply, but they’re not required to. That means reading ingredient labels isn’t optional here. It’s the only real protection your cat has.

This glossary breaks down every cat food ingredient to avoid, explains why it’s used, what the health risks are, and what to look for instead. Bookmark it. Pull it up on your phone at the pet shop. It’s meant to be a reference you use.

Take our quiz to see what a clean, transparent ingredient list looks like for your cat’s specific needs.

How to Use This Glossary (And How to Read a Cat Food Label)

Before jumping into individual ingredients, a quick primer on how ingredient panels work.

Ingredients are listed by weight before cooking. The first three to five ingredients make up the bulk of the food. If the first few entries are grains, by-products, or fillers, you’re looking at a product that’s mostly cheap padding.

Watch for the moisture trick. Whole “chicken” weighs more than “chicken meal” (which has had the water removed). Chicken might appear first on the label, but on a dry matter basis, it would rank much lower. This is how manufacturers make grain-heavy formulas look meat-first.

Learn AAFCO naming rules. A product labelled simply “Chicken” or “Chicken for Cats” must contain at least 95% chicken. “Chicken Dinner” only needs 25%. “With Chicken” drops to 3%. And “Chicken Flavor”? That requires only a detectable trace. These rules apply to US-regulated products, and since Australia generally follows AAFCO guidelines as a reference, they’re a useful benchmark here too.

Carbohydrates are hidden by design. AAFCO doesn’t require carbohydrate content on the guaranteed analysis panel. To figure out how much carbohydrate is really in your cat’s food, you need a carb calculator and a dry matter basis conversion. No regulatory body, including AAFCO and FEDIAF, sets a minimum carbohydrate requirement for cats because cats don’t need them.

Now, onto the ingredients.

Glossary: Cat Food Ingredients to Avoid

Artificial Preservatives: BHA, BHT, and Ethoxyquin

What they are: Synthetic chemicals used to prevent fats from going rancid and extend shelf life.

Why they’re concerning: BHA (butylated hydroxyanisole) is listed by the US National Toxicology Program as “reasonably anticipated to be a human carcinogen” based on animal studies. California’s Office of Environmental Health Hazard Assessment includes BHA on its list of known carcinogens and reproductive toxicants. BHT carries similar concerns, with animal studies linking it to tumours and liver damage.

Ethoxyquin is prohibited in human food due to potential for serious harm, yet it remains permitted in pet food. Studies have linked it to liver and kidney damage and potential reproductive effects. Some pet food manufacturers have voluntarily removed it.

Here’s a fact most people miss: the EU does not authorise BHA for use in cat food specifically, while allowing it for other animal species. If European regulators treat BHA as unsuitable for cats in particular, that’s worth paying attention to.

The risk isn’t from a single meal. It’s cumulative exposure over years, especially for kittens and cats with developing or compromised systems.

Where it hides on labels: Look for “BHA,” “BHT,” “butylated hydroxyanisole,” “butylated hydroxytoluene,” or “ethoxyquin.” Sometimes these appear in a fat or fish meal sub-ingredient and won’t be listed on the main panel.

Better alternative: Natural preservatives like mixed tocopherols (vitamin E family), vitamin C, and rosemary extract are safe antioxidants that slow oxidation effectively. For a deeper look, read our guide on cat food without preservatives.

Unnamed Meat By-Products and Generic Meat Meals

What they are: Vague protein sources listed as “meat by-products,” “poultry meal,” “animal meal,” or just “meat.” These terms tell you nothing about what animal the protein came from, let alone which parts.

Why they’re concerning: Rendered ingredients may include what the industry calls 4D meats, meaning animals that were dead, dying, diseased, or disabled before processing. Feed-grade ingredients (as opposed to human-grade) can legally include these materials along with by-products, chemicals, and fillers that would never pass FDA standards for human consumption.

A named animal protein like chicken, turkey, or salmon should always lead the ingredient list. Vague terms in top positions signal low-quality sourcing and make it impossible to identify or avoid specific allergens.

Where it hides on labels: “Meat and bone meal,” “animal by-products,” “poultry by-product meal,” “meat meal.” Any protein source that doesn’t name the specific animal is a red flag.

Better alternative: Named, single-source proteins (e.g., “chicken breast,” “beef,” “sardine”). Ideally, human-grade ingredients that meet the same safety standards as food produced for people.

Corn, Wheat, Soy, and Refined Grain Fillers

What they are: Cheap carbohydrate sources used to bulk up cat food at low cost. The corn and wheat used in cat food are typically refined, stripped of whatever limited nutritional value the whole grain might have offered.

Why they’re concerning: Cats are obligate carnivores. No regulatory body sets a minimum carbohydrate requirement for cats because they don’t need carbohydrates to thrive. Heavy reliance on these fillers displaces the animal protein cats actually require.

Practitioners on pet nutrition forums have pointed out just how bad some formulas get. One analysis by Jess Caticles (a pet nutritionist in training) found products where the first five ingredients were ground yellow corn, corn gluten meal, chicken by-product meal, soybean meal, and beef tallow, with no actual meat and three out of five ingredients being carbohydrate sources.

Soy also contains phytoestrogens, which may affect hormonal balance, and is a common allergen for cats.

Where it hides on labels: “Ground corn,” “corn gluten meal,” “wheat flour,” “wheat middlings,” “soybean meal,” “brewers rice,” “ground yellow corn.” Manufacturers sometimes split a single grain into multiple named forms (corn + corn gluten meal + corn starch) so each appears lower on the list individually.

Better alternative: Meat-first formulas where animal protein dominates the first several ingredients. Our guide on cat food without fillers covers this in detail.

Artificial Colours: Red 40, Yellow 5, Yellow 6, Blue 2

What they are: Synthetic dyes added to kibble and wet food to make it look more appealing, but only to the person buying it.

Why they’re concerning: Cats don’t care whether their kibble is red, green, or orange. These dyes serve zero nutritional purpose and exist entirely for human marketing. Studies in rodents have raised concerns about links between artificial dyes and behavioural effects, allergic reactions, and potential carcinogenicity. Red 40, Blue 2, Yellow 5 and Yellow 6 are the most common offenders in pet food.

Where it hides on labels: Listed as “Red 40,” “Yellow 5,” “Yellow 6,” “Blue 2,” or by their E-number equivalents (E129, E102, E110, E133). Also watch for “iron oxide,” which is used as a colouring agent.

Better alternative: Food that looks like food. Fresh or minimally processed cat food doesn’t need dye because the ingredients themselves provide the colour.

Carrageenan

What it is: A thickening and gelling agent extracted from red seaweed. It’s common in wet cat food and canned pâtés to create that smooth, uniform texture.

Why it’s concerning: This one is genuinely debated in the veterinary community. A DVM and animal nutritionist has stated that “the evidence regarding carrageenan’s safety remains inconclusive, with some studies indicating potential harm and others suggesting it is safe for consumption.” The key distinction is between food-grade carrageenan and degraded carrageenan (poligeenan). Degraded carrageenan has been linked to inflammation, inflammatory bowel disease, and colon cancer. Some reports suggest that even food-grade carrageenan contains small amounts of the degraded form.

A 2021 study by K.T. Williams found that cats consuming carrageenan-heavy diets had lower nutrient absorption levels compared to cats on carrageenan-free diets.

Where it hides on labels: Listed as “carrageenan” or occasionally “Irish moss extract.”

Better alternative: If you want to avoid the uncertainty entirely, fresh food formats that don’t need thickeners eliminate the question. Otherwise, look for alternatives thickened with agar-agar or simply served in natural broth.

Added Sugars and Caramel Colour

What they are: Sugars (sucrose, caramel, molasses, corn syrup) added to cat food, most commonly in wet food and treats.

Why they’re concerning: Cats cannot taste sweetness. Their taste receptors lack the ability to detect sugar, so adding it to cat food does nothing for the cat’s eating experience. Users on petforums.co.uk have noted that “the sugar is usually in there to make the product look more appealing (i.e. browner) to the pet owner.” Caramel colour is used to give wet food that rich gravy appearance that humans find appetising.

Meanwhile, sugar contributes empty calories, promotes dental problems, and feeds the obesity epidemic. Roughly 43% of cats are overweight or obese, and hidden sugars in food don’t help.

Where it hides on labels: “Sugar,” “sucrose,” “caramel colour,” “caramel,” “molasses,” “corn syrup,” “dextrose,” “fructose.”

Better alternative: Food that derives its palatability from actual meat flavour, not sugar coating.

Propylene Glycol

What it is: A synthetic additive used as a humectant (moisture-retaining agent) in semi-moist pet foods and treats.

Why it’s concerning: Propylene glycol is explicitly not permitted in cat food because it causes Heinz body formation in cat red blood cells. This can lead to anaemia. It’s worth noting that it is still allowed in dog food, so multi-pet households should keep dog treats away from cats.

Where it hides on labels: Listed as “propylene glycol.” It shouldn’t appear in cat food at all, so its presence indicates either a labelling error or a product not compliant with AAFCO regulations.

Better alternative: Any cat food that maintains moisture through high meat content or natural broth rather than chemical humectants.

Rendered Fats from Unnamed Sources

What they are: Fats produced through rendering, a process where animal tissues are heated at high temperatures to separate fat from protein and moisture. When the source animal isn’t named, it’s usually labelled as “animal fat” or “poultry fat” rather than “chicken fat” or “beef tallow.”

Why they’re concerning: The rendering industry processes over 47 billion pounds of raw animal materials annually. Unnamed sources mean the fat could come from any animal, including 4D meats. The high-temperature rendering process also strips fats of quality nutrients. These generic fats are more prone to rancidity, which is why they often require the synthetic preservatives discussed earlier.

Where it hides on labels: “Animal fat,” “poultry fat” (without specifying which bird), “animal digest,” “meat fat.”

Better alternative: Named fat sources like “chicken fat” or “salmon oil.” Even better: whole food formats where fat comes naturally from the named protein.

Sodium Nitrate and Titanium Dioxide

What they are: Sodium nitrate is a flavour enhancer and preservative. Titanium dioxide is a whitening agent used to make food appear brighter and more uniform in colour.

Why they’re concerning: Sodium nitrate can convert into nitrosamines, which are recognised carcinogens. Titanium dioxide has been linked to DNA damage, chromosomal disruption, inflammation, and cancer in some studies. The EU banned titanium dioxide as a food additive for humans in 2022, though it remains permitted in pet food.

Where it hides on labels: “Sodium nitrate,” “sodium nitrite” (a related compound), “titanium dioxide,” “E171.”

Better alternative: Fresh food that doesn’t need chemical colour enhancement or synthetic preservation.

Thickening Gums: Guar Gum, Xanthan Gum, Cassia Gum

What they are: Processed thickening agents added to wet cat food to improve texture and consistency.

Why they’re concerning: These ingredients offer zero nutritional value. They exist purely for texture engineering. While not acutely toxic, they can cause digestive upset in sensitive cats, and some practitioners on Reddit have reported that cats with IBD or chronic GI issues improved after switching to gum-free foods. The concern is displacement: every bit of thickener is taking the place of something nutritionally useful.

Where it hides on labels: “Guar gum,” “xanthan gum,” “cassia gum,” “locust bean gum,” “cellulose gum.”

Better alternative: Wet food thickened naturally through high meat content, or fresh food formats that don’t require binding agents.

Onion, Garlic, and Alliums

What they are: Members of the Allium family, including onions, garlic, leeks, chives, and shallots.

Why they’re concerning: All alliums are toxic to cats. They damage red blood cells and can cause oxidative haemolytic anaemia. While these aren’t common in complete cat food formulas, they show up in broths, gravies, toppers, and meal mixers, products that many cat owners don’t scrutinise as carefully as they do main meals. Table scraps are another common exposure route.

Where it hides on labels: “Onion powder,” “garlic powder,” “garlic extract,” “dehydrated onion,” “chive.” Also check human food products that owners might share with cats.

Better alternative: Cat-specific broths and toppers formulated without alliums.

“Natural Flavour” and Animal Digest

What they are: Vague palatability enhancers sprayed onto or mixed into cat food to make it smell and taste appealing. “Animal digest” is produced by chemical or enzymatic hydrolysis of animal tissue, and the source animal is often unspecified.

Why they’re concerning: These terms tell you nothing about what’s actually in the product. “Natural flavour” has no strict definition in pet food and can encompass a wide range of processed materials. Animal digest is a particular concern because it can come from virtually any animal source, making allergen identification impossible. When a cat is a fussy eater, palatant-coated food may initially seem appealing but masks poor underlying nutrition.

Where it hides on labels: “Natural flavour,” “natural flavors,” “animal digest,” “liver digest,” “meat digest.”

Better alternative: Food that’s palatable because of its actual ingredients. Cats respond well to real meat cooked gently to preserve natural aromas.

Excessive Plant Proteins: Corn Gluten Meal, Wheat Gluten, Soy Protein

What they are: Concentrated protein extracts from plants, used to inflate the total protein percentage on the guaranteed analysis without using expensive animal protein.

Why they’re concerning: The protein number on the label looks good, but plant proteins have a different amino acid profile than animal proteins. Cats need taurine, arachidonic acid, and specific amino acids that only come from animal sources. A cat food with 35% protein that’s half corn gluten meal is not equivalent to one with 35% protein from chicken. The cat’s body can’t use it the same way.

Where it hides on labels: “Corn gluten meal,” “wheat gluten,” “soy protein isolate,” “soy protein concentrate,” “pea protein.” When these appear high on the ingredient list alongside vague meat sources, the formula is probably plant-protein-padded.

Better alternative: Whole named animal proteins as the dominant protein source. Check that the first two or three ingredients are all animal-derived.

Sulphite Preservatives (220 to 228): An Australian-Specific Danger

What they are: Sulphur dioxide and related sulphite preservatives (identity numbers 220, 221, 222, 223, 224, 225, and 228) commonly added to pet meat, pet mince, and pet rolls sold in Australian supermarkets and butchers.

Why they’re concerning: This is the ingredient most likely to be missing from international “cat food ingredients to avoid” lists, because it’s primarily an Australian problem. Sulphite preservatives destroy thiamine (vitamin B1). Cats fed exclusively on sulphite-treated pet meats can develop fatal thiamine deficiency.

University of Sydney veterinarian Dr. Anne Fawcett has warned that “sulphite preservatives are added to some pet meats, sometimes at very high levels, to mask the signs of putrefaction.” In plain English: these chemicals hide the fact that the meat is rotting.

The Australian Veterinary Association explicitly warns that cats can suffer fatal health problems if fed exclusively with pet mince, pet meat, or pet rolls containing high levels of sulphur dioxide. Thiamine deficiency cases associated with sulphite-treated pet food have been reported regularly in Australian veterinary literature, and the true incidence is likely significantly under-reported.

Where it hides on labels: Look for any number in the 220 to 228 range, or the terms “sulphur dioxide,” “sodium sulphite,” “sodium bisulphite,” “sodium metabisulphite,” or “potassium metabisulphite.” These appear most often on fresh pet meat sold in butcher sections or pet food aisles, rather than in canned or dry food. For more on the safety differences between raw pet meat and cooked alternatives, see our comparison of fresh vs raw cat food.

Better alternative: Human-grade meats that don’t require sulphite preservation, or complete fresh meals processed under conditions that don’t need chemical shelf-life extension.

Why Australian Cat Owners Need to Be Even More Careful

Most international guides on cat food ingredients to avoid assume their readers live in countries with mandatory pet food safety regulation. Australia is different.

Australia has no equivalent to AAFCO (which sets standards in the US) or FEDIAF (which governs pet food in Europe). There is no government research facility that performs feeding trials for pet food here. The Australian Standard AS 5812-2011 provides guidelines for manufacturing and labelling, but it is currently voluntary. Manufacturers are “urged” to comply, not required.

In practice, this means Australia generally follows AAFCO requirements as a reference point and relies on imported products to meet the regulations of their country of origin. For locally manufactured cat food, compliance with any standard is essentially on the honour system.

This regulatory gap makes ingredient label reading more important in Australia than almost anywhere else. You can’t rely on a government safety net to catch the worst offenders. The responsibility falls on you.

The sulphite issue is a perfect example. In many countries, the preservatives used in Australian pet meats would either be banned or strictly regulated. Here, they’re common, sometimes at dangerously high levels, and the AVA has been sounding the alarm for years.

What Good Cat Food Ingredients Look Like

Knowing what to avoid is only half the picture. Here’s what a clean ingredient panel looks like.

Named animal proteins first. Chicken, beef, salmon, turkey, or another specifically identified animal should be the first (and ideally the second) ingredient. Not “poultry” or “meat.” The actual animal.

Short, recognisable ingredient lists. If you can’t pronounce most of the ingredients, or if the list runs to 30+ items, that’s a warning sign. The best cat foods have ingredient lists that read like a recipe, not a chemistry experiment.

Natural preservatives. Mixed tocopherols (vitamin E), ascorbic acid (vitamin C), and rosemary extract are effective, safe preservatives that don’t carry the cancer risk of BHA, BHT, or ethoxyquin.

High moisture content. Cats evolved to get most of their water from food. Wet food or fresh food with 60 to 80% moisture supports kidney and urinary health far better than dry kibble at 10% moisture.

Complete and balanced statement. Look for an AAFCO “complete and balanced for all life stages” statement, which means the food meets established nutritional profiles. This matters more than marketing claims like “premium” or “natural,” which have no legal definition.

Transparent nutritional panels. Good brands publish full macronutrient breakdowns per recipe. You shouldn’t have to guess whether you’re feeding your cat 30% protein or 50%. See what transparent panels look like on Pikko’s recipe pages.

The simplest way to avoid most of the ingredients in this glossary is to choose fresh, gently cooked food made from human-grade ingredients. When the food starts as real meat cooked at gentle temperatures and frozen for preservation, there’s no need for artificial preservatives, thickening gums, dyes, rendered mystery fats, or plant protein fillers. The bad ingredients simply aren’t there because the food doesn’t need them.

Quick-Reference Cheat Sheet: Avoid vs. Look For

Avoid	Look For Instead
BHA, BHT, ethoxyquin	Mixed tocopherols, vitamin E, rosemary extract
“Meat by-products,” “poultry meal” (unnamed)	Named proteins: chicken, beef, salmon, turkey
Corn, wheat, soy as primary ingredients	Meat-first formulas, minimal or no grain fillers
Red 40, Yellow 5, Blue 2, iron oxide	No added colours (food should look like food)
Carrageenan	Natural broth, agar-agar, or fresh food formats
Added sugar, caramel colour	Real meat-based gravies, no added sweeteners
Propylene glycol	High-moisture meat, natural broth
“Animal fat” (unnamed)	Named fats: chicken fat, salmon oil
Sodium nitrate, titanium dioxide	No chemical colour or flavour enhancers
Guar gum, xanthan gum, cassia gum	Whole-food textures, minimal processing
Onion, garlic powder (in toppers/broths)	Cat-specific broths without alliums
Sulphites 220 to 228 (AU pet meats)	Human-grade meat, gently cooked meals
“Natural flavour,” animal digest	Transparent, named ingredients
Corn gluten meal, soy protein isolate	Whole animal proteins as dominant protein source

Ready to Switch?

If this glossary has you questioning what’s in your cat’s current food, you’re not alone. The good news is that switching doesn’t have to be complicated. A gradual transition over 7 to 10 days works for most cats, and even fussy eaters can come around with the right approach. Our transition guide walks through both gradual and direct methods.

Try Pikko’s trial box to see what fresh, human-grade cat food with a transparent ingredient list looks and smells like. Every pouch lists exactly what’s inside, nothing more.

Frequently Asked Questions

Are by-products always bad in cat food?

Not necessarily. Named by-products from a specific animal (like “chicken liver” or “chicken heart”) can be nutritious. Organ meats are part of a cat’s natural diet. The problem is with unnamed, generic by-products where you can’t identify the source animal or the specific tissues used. Vague labels like “meat by-products” or “animal by-product meal” make it impossible to assess quality or identify allergens.

Is grain-free cat food automatically better?

Not always. Some grain-free formulas simply replace grains with other high-carbohydrate ingredients like potatoes, peas, or tapioca starch. The total carbohydrate content can be just as high. What matters more than the “grain-free” label is whether the food is meat-first, with animal protein dominating the first several ingredients and total carbohydrate content staying low.

Why do so many cat foods contain ingredients cats don’t need?

Cost. Corn, wheat, soy, and plant protein concentrates are dramatically cheaper than animal protein. Artificial preservatives are cheaper than natural ones. Thickeners and gums are cheaper than using enough real meat to create texture naturally. The cat food industry formulates many products to a price point, not to a cat’s biological needs.

How can I check the carbohydrate content if it’s not on the label?

AAFCO doesn’t require carbohydrate disclosure on the guaranteed analysis panel. To calculate it yourself, add up the percentages of protein, fat, moisture, fibre, and ash listed on the label. Subtract that total from 100. The remainder is an approximate carbohydrate percentage. Then convert to dry matter basis for an accurate comparison between wet and dry foods.

Are sulphite preservatives only in raw pet meat, or in canned food too?

Sulphites (220 to 228) are primarily found in fresh, raw, or semi-raw pet meats, pet mince, and pet rolls sold in Australian supermarkets and butcher shops. They’re uncommon in canned or dry cat food because those formats use other preservation methods (heat sterilisation, low moisture). The risk is highest for cat owners who buy “pet meat” from the chilled section and feed it as a sole diet.

What’s the difference between human-grade and feed-grade cat food?

Human-grade means every ingredient and the manufacturing facility meet the standards required for human food production. Feed-grade means the finished product is not suitable for human consumption by FDA standards and may include by-products, lower-quality materials, and 4D meats. In Australia, where pet food regulation is voluntary, the distinction matters even more because there’s less oversight of feed-grade products.

Can I trust a cat food that says “natural” on the label?

The word “natural” has no strict, enforceable legal definition in pet food labelling, particularly in Australia. A product labelled “natural” can still contain rendered by-products, high levels of plant fillers, and other ingredients you’d want to avoid. Always read the actual ingredient list rather than relying on front-of-pack marketing claims.