The following are chemical / synthetic additives found in many pet supplements and foods, which we believe are best avoided for the reasons stated.
It is not meant to be an exhaustive list and so if you see an ingredient you don't recognise on a product label, be sure to research it online.
In many cases these substances are included not the benefit of pets, but the manufacturer such as to facilitate production or to create a significantly cheaper product, for example.
NOTE:
Some of the additives are included more than once because they have multiple uses.
1. Artificial Colours:
- E102 Tartrazine
- E104 Quinoline Yellow
- E110 Sunset Yellow FCF
- E122 Carmoisine / Azorubine
- E124 Ponceau 4R
- E127 Erythrosine
- E129 Allura Red AC
- E131 Patent Blue V
- E133 Brilliant Blue FCF
- E151 Brilliant Black PN
- E155 Brown HT
- E150c / E150d Caramel colours
- Titanium dioxide (E171)
Why avoid?
Artificial colours are added mainly to make a product look more appealing to humans, not because they benefit the dog or cat. Several synthetic colours remain authorised additives in Great Britain, but they have no nutrtional value and are best avoided for this reason.Titanium dioxide remains permitted in Great Britain, although it was banned in the EU after EFSA concluded that a genotoxicity concern could not be ruled out.
2. Artificial Preservatives, Antioxidants and Shelf-Life Extenders:
- E310 Propyl gallate
- E320 BHA
- E321 BHT
- TBHQ
- Ethoxyquin
- E200 Sorbic acid
- E202 Potassium sorbate
- E210 Benzoic acid
- E211 Sodium benzoate
- E212 Potassium benzoate
- E213 Calcium benzoate
- E214–E219 Parabens / hydroxybenzoates
- E220 Sulphur dioxide
- E221 Sodium sulphite
- E222 Sodium bisulphite / hydrogen sulphite
- E223 Sodium metabisulphite
- E224 Potassium metabisulphite
- E226 Calcium sulphite
- E227 Calcium hydrogen sulphite
- E237 Sodium formate
- E280–E283 Propionic acid / sodium, potassium and calcium propionates
- E325 Sodium lactate
- E326 Potassium lactate
- E327 Calcium lactate
- E330 Citric acid
- Sodium nitrite
- Sodium nitrate
- Potassium nitrate
Why avoid?
This is one of the most important categories to scrutinise.
Preservatives can be useful from a manufacturing standpoint, but in pet supplements they often signal a formulation built first around shelf life and processing convenience rather than freshness or ingredient quality.
Some are mainly “clean-label negatives,” but others are of more concern:
- sulphur dioxide and related sulphites can destroy thiamine, which is particularly important in cats and can contribute to serious neurologic disease
- nitrates and nitrites can cause methemoglobinemia and impaired oxygen delivery
- synthetic antioxidants such as BHA, BHT, TBHQ and ethoxyquin are widely avoided by manufacturers aiming for a less chemically burdened product
- sodium benzoate in combination with vitamin C can form benzene which is a known carcinogen
3. Artificial Sweeteners:
- Sucralose
- Xylitol
- Aspartame
- Saccharin
- Acesulfame-K
- Neotame
Why avoid?
Artificial sweeteners are unnecessary in a pet supplement and are often there to make a heavily processed product more palatable to the owner’s eye or the animal’s tongue.
Not only this, xylitol is acutely dangerous to dogs and can cause rapid hypoglycaemia, seizures, liver failure and death.
The others are not as hazardous, but none are needed in a properly designed pet supplement, and all are examples of human-style ultra-processed formulations creeping into animal products.
4. Anti-caking Agents, Flow Agents and Lubricants:
- E551 Silicon dioxide
- Silica
- E572 Magnesium stearate
- Stearic acid
- Calcium stearate
- Sodium stearyl fumarate
- Talc (where used industrially in processing)
- Tricalcium phosphate
- Magnesium oxide (when used mainly as a processing aid)
- Aluminium silicates / related mineral anti-caking agents
Why avoid?
These substances are usually added to improve manufacturing efficiency by helping powders flow, preventing clumping, or lubricating machinery. They are not there for the pet’s benefit. In some cases they are tolerated as low-level excipients, but their presence can indicate a product designed around industrial handling characteristics rather than nutrient density or food quality. Where a supplement contains multiple flow agents and lubricants, that is often a sign of a highly processed, powder-engineered formula rather than a nurtionally rich product intended to provide significant health benefits.
5. Emulsifiers, Gelling Agents and Thickeners:
- E322 Lecithins
- Mono- and diglycerides of fatty acids
- Polysorbate 80
- E407 Carrageenan
- E407a Processed eucheuma seaweed
- E410 Locust bean gum
- E412 Guar gum
- E413 Tragacanth
- E414 Acacia / gum arabic
- E415 Xanthan gum
- E417 Tara gum
- E418 Gellan gum
- E440 Pectins
- E466 Sodium carboxymethyl cellulose
- Carboxymethyl cellulose
- Cassia gum
- E401–E405 Alginates / propylene glycol alginate
Why avoid?
These ingredients are used to bind ingredietns, suspend particles, thicken liquids, create a “chewy” structure, or improve mouthfeel. Some are tolerated in small amounts, but they remain processing aids rather than nutrients. In pet supplements they are often used to disguise weak formulation, stretch a product, or create a more marketable texture. Gums and cellulose-based thickeners may also worsen stool quality or contribute to GI irritation in sensitive animals. The more a supplement relies on a network of gums, stabilisers and texturisers, the less it resembles real food.
6. Fillers, Binders, Bulking Agents and Highly Processed Carbohydrate Derivatives:
- Microcrystalline cellulose
- Cellulose
- Powdered cellulose
- Corn gluten meal
- Corn protein concentrate
- Soy protein isolate
- Wheat gluten
- Vital wheat gluten
- Maltodextrin
- Dextrose
- Corn syrup solids
- Glucose syrup solids
- Rice syrup solids
- Dextrins
- Modified starches, including: E1404 Oxidised starch, E1410 Monostarch phosphate, E1412 Distarch phosphate, E1413 Phosphated distarch phosphate, E1414 Acetylated distarch phosphate, E1420 Acetylated starch, E1422 Acetylated distarch adipate, E1440 Hydroxypropyl starch, E1442 Hydroxypropyl distarch phosphate, E1450 Starch sodium octenyl succinate
- Pea fibre, oat fibre, bamboo fibre where used mainly as bulk
- Inulin where used chiefly as filler rather than at a genuinely functional level
Why avoid?
This category is less about toxicity and more about product honesty and biological appropriateness.
These substances are frequently used to bulk out a supplement cheaply, improve handling, reduce stickiness, standardise texture or replace more expensive active ingredients.
That may make manufacturing easier, but it can dilute nutritional value and add unnecessary carbohydrate or indigestible bulk.
In some animals, excessive fibre or poorly chosen refined carbohydrate fillers can also reduce digestibility or aggravate gastrointestinal sensitivity. In short, these ingredients often point to cost engineering rather than health optimisation.
7. Flavours, Palatants, Solvents and Humectants:
- Artificial meat flavours
- Artificial smoke flavour
- Artificial bacon / cheese / roast flavours
- Animal digest
- Hydrolysed vegetable protein
- Yeast extract
- Autolysed yeast
- MSG
- Propylene glycol
- Glycerol / glycerin
- Benzyl alcohol
- PEGs / polyethylene glycols
- Triacetin
- Triethyl citrate
- Butylene glycol
Why avoid?
These are classic “make it sell, make it stable, make it taste stronger” ingredients. They often add nothing nutritionally and may be used to mask the taste or smell of inferior raw materials. The most important caution here is propylene glycol: the FDA states that it is not considered safe as an additive in cat food because cats are particularly susceptible to red blood cell damage from it. Even where not outright prohibited, this whole class of flavour systems, solvents and humectants tends to reflect a highly manipulated formulation rather than a clean, food-based supplement.
8. Synthetic Amino Acids and Other Isolated Nitrogenous Nutrients:
- DL-methionine
- L-lysine
- Lysine hydrochloride
- Tryptophan
- Taurine
- L-carnitine
- Arginine
- Threonine
- Valine
- Isoleucine
- Leucine
- Histidine
- Phenylalanine
- Synthetic choline compounds, such as choline chloride
Why avoid?
Synthetic amino acids are not automatically harmful; some are essential and in certain clinical contexts they may be useful or necessary. However, when a supplement leans heavily on isolated, industrially produced amino acids, the risk is that it may be compensating for a nutritionally poor base rather than delivering nourishment in a naturally balanced form.
DL-methionine is a good example. It has specific uses in the body, but is still a synthetic acidifying amino-acid additive rather than something that naturally occurs as part of a whole-food protein matrix. As such natural sources of amino acids are much preferred if optimisation of health is the goal.
9. Synthetic Vitamins and Mineral / Trace Element Additions:
- Vitamin A (retinyl acetate, retinyl palmitate)
- Vitamin D3 (cholecalciferol)
- Vitamin E (synthetic alpha-tocopherol forms)
- Vitamin K
- Vitamin K3 / menadione compounds
- menadione sodium bisulphite
- menadione sodium bisulphite complex
- menadione nicotinamide bisulphite
- Vitamin B1
- Vitamin B2
- Vitamin B6
- Vitamin B12
- Niacin
- Folic acid
- Biotin
- Calcium pantothenate
- Beta-carotene
- Vitamin C
- Sodium ascorbate
- Vitamin C monophosphate
- Synthetic / inorganic minerals and trace elements
- Calcium carbonate
- Calcium sulphate
- Calcium iodate
- Calcium propionate
- Monodicalcium phosphate
- Phosphorus salts
- Potassium chloride
- Potassium iodide
- Sodium chloride
- Sodium hexametaphosphate
- Sodium selenite
- Selenium
- Zinc oxide
- Zinc sulphate
- Zinc chelates
- Ferrous sulphate
- Iron sulphate
- Ferrous chelates
- Cupric sulphate
- Cupric chelates
- Cobaltous carbonate
- Manganese oxide
- Manganous sulphate
- Manganese chelates
- Magnesium oxide
- Magnesium sulphate
- Copper carbonate
- Copper chloride
- Sodium molybdate
- Sodium phosphate salts
- Aluminium-containing mineral additives
Why avoid?
Vitamins and minerals are of course essential, and the issue is not that these nutrients exist, but that isolated synthetic or inorganic forms can be used as a cheap way to “fortify” an otherwise poor-quality product. Some forms are less biologically avaialble, less balanced, or more prone to overuse than nutrients delivered through high-quality whole foods and extracts.
Menadione-type vitamin K3 compounds are especially controversial compared with natural vitamin K1.
Inorganic minerals also deserve caution because excessive or poorly balanced supplementation can create nutrient antagonisms or even toxicity in susceptible animals.
10. Ethically Problematic or High-Risk Animal-Derived Industrial Ingredients:
- Chondroitin from shark cartilage
- Chondroitin from intensive poultry by-products
- Low-grade rendered animal proteins
- Anonymous “animal derivatives”
- Unspecified collagen hydrolysates
- Unspecified gelatins
- Rendered digest coatings
- Factory-farmed organ or cartilage extracts with poor traceability
Why avoid?
The prime concern here is less about potential toxicity and more about quality, sourcing, transparency and ethics.
Animal-derived ingredients can be excellent when well sourced and clearly identified, but low-grade, anonymous or industrially rendered materials are best avoided because they can be nutritionally inconsistent, ethically questionable, and hard to assess for purity or contamination risk.
Chondroitin is a good example: the substance itself is not inherently bad, but if it comes from poorly traceable, low-welfare or ecologically problematic sources, that is a legitimate reason to avoid it. In premium supplements, source transparency matters as much as the ingredient identity.