Ultra-Processed Pet Food: What the Research Is Starting to Show

By Sarah Bennett, Certified Animal Nutritionist

The term "ultra-processed food" has become one of the most discussed concepts in human nutrition science over the past decade. Defined broadly by the NOVA classification system as industrially manufactured formulations containing ingredients not typically found in home kitchens — synthetic emulsifiers, flavour enhancers, hydrogenated fats, artificial colourants, texturisers — ultra-processed foods have been associated in large epidemiological studies with increased risks of cardiovascular disease, type 2 diabetes, obesity, and all-cause mortality in humans. Now, a smaller but growing body of research is asking whether the same concerns apply to the ultra-processed foods that constitute the vast majority of what companion animals eat every day.

The question matters enormously. The overwhelming majority of pet food sold globally — standard dry kibble, most wet foods, treat products — would qualify as ultra-processed under NOVA criteria. Dogs and cats in modern households often eat the same formulation, meal after meal, for their entire lives. If ultra-processing introduces health risks through mechanisms beyond simple macro- and micronutrient content, the implications for companion animal health could be significant.

Defining Ultra-Processed: What Makes Pet Food "Ultra-Processed"?

The NOVA classification system, developed by researchers at the University of São Paulo, organises foods into four groups based on the degree of industrial processing. Group 4 — ultra-processed foods — includes products that are manufactured using industrial processes and ingredients that either don't exist in natural foods or are derived from food components through industrial processing. These include hydrolysed proteins, modified starches, maltodextrin, artificial flavours, synthetic colours, emulsifiers such as carrageenan and lecithin, and preservatives.

Standard dry kibble for dogs and cats typically contains many of these ingredients. The extrusion process used to make kibble involves exposing ingredients to very high temperatures and pressures, which can degrade heat-sensitive vitamins and alter protein structures in ways that differ from raw or minimally processed food. Manufacturers compensate by adding back synthetic vitamins and minerals — a further step of industrial fortification characteristic of ultra-processed formulations.

As The Guardian's reporting on ultra-processed pet food risks highlighted, researchers are increasingly applying the NOVA framework to pet food analysis and finding that the vast majority of commercially available complete pet foods qualify as ultra-processed by these criteria. This does not automatically mean they are harmful — but it raises questions that deserve rigorous scientific investigation.

What Does the Research Show?

The direct research on ultra-processed pet food and health outcomes is limited compared to the human nutrition literature, but what exists is beginning to tell a consistent story. A 2022 study published in PLOS ONE (PMID 36082337) analysed the dietary patterns of over 2,500 dogs and found that dogs fed raw or minimally processed diets had significantly better owner-reported health scores across multiple domains — including coat quality, faecal consistency, energy levels, and gastrointestinal health — compared to dogs fed exclusively commercial ultra-processed diets. The study was observational and relied on owner reporting, which introduces important limitations, but the size of the effect observed was notable.

Research covered by Science Daily on processed pet food has pointed to specific mechanisms by which ultra-processing may affect pet health beyond simple nutrient delivery. The Maillard reaction — a chemical reaction between amino acids and sugars that occurs during high-heat processing — generates compounds called advanced glycation end-products (AGEs). AGEs accumulate in tissues and have been associated with oxidative stress and inflammation in both humans and animals. Extruded kibble contains substantially higher AGE concentrations than raw or lightly cooked pet foods.

Additionally, the preservation systems used in ultra-processed pet foods — including synthetic antioxidants like BHA (butylated hydroxyanisole) and BHT (butylated hydroxytoluene) — have raised questions about long-term safety at the concentrations present in food consumed daily over years. While regulatory bodies have set maximum permitted levels, these limits are generally based on short-term toxicology rather than lifetime exposure studies in companion animals.

The Regulatory Framework: What's Actually Permitted?

Pet food in both the EU and the US is regulated, but the frameworks differ substantially from human food standards. In the US, the FDA's guidelines on pet food require that products be safe, produced under sanitary conditions, contain no harmful substances, and be truthfully labelled. The AAFCO (Association of American Feed Control Officials) sets nutritional adequacy standards. However, neither body proactively evaluates all additives used in pet food for long-term health effects at population scale.

In the EU, Regulation (EC) No 767/2009 on the placing on the market and use of feed for animals sets standards for pet food labelling and composition, and Regulation (EC) No 1831/2003 governs permitted additives. These are more prescriptive than US standards in some respects, but the fundamental regulatory gap remains: there are no requirements for manufacturers to demonstrate long-term health outcomes associated with their specific formulations.

Ultra-Processed Food and the Gut Microbiome

One of the most compelling proposed mechanisms by which ultra-processed pet food might affect health is through the gut microbiome. Research in humans has established clearly that dietary emulsifiers — including carboxymethylcellulose and polysorbate-80, both used in pet food — can disrupt the mucus layer of the intestine and alter microbial community composition in ways that promote low-grade inflammation. Studies in mice have shown that even low concentrations of these emulsifiers, at levels found in processed foods, can induce changes in gut bacteria associated with metabolic syndrome.

Whether the same effects occur in dogs and cats at the concentrations present in commercial pet food is not yet established. However, as BBC's coverage of ultra-processed food research has noted, the mechanistic evidence in rodent models and human cohort data is sufficient that researchers are now actively investigating these pathways in companion animals. The gut microbiome is increasingly recognised as central to immune function, inflammatory regulation, and even mental health in dogs and cats, making this a high-priority area for future research.

Practical Guidance: What Can Pet Owners Do Now?

Given that the evidence is emerging but not yet definitive, and that the practical reality is that most pets are fed commercial processed foods with no ill effects observable in routine veterinary checks, the appropriate response is calibrated rather than alarmist. Here is what the current science supports:

First, variety matters. Feeding the same ultra-processed food every day for years means any risks associated with specific ingredients or processing by-products accumulate without break. Where budget allows, rotating between different protein sources and food formats (including some minimally processed options) may reduce cumulative exposure to any individual problematic compound.

Second, ingredient quality within the ultra-processed category varies substantially. A kibble made with named meat sources, minimal synthetic additives, and without artificial colours or flavours represents a better choice within the ultra-processed tier than a budget product with hydrolysed protein of unclear origin and a long additives list. Reading ingredient labels matters.

Third, supplementing with fresh, minimally processed whole foods — where safe and appropriate to the species — may partially offset some of the concerns around ultra-processing. For dogs, this might mean adding some fresh vegetables, a small amount of cooked meat, or a quality topper to their primary diet. Cats have more specific nutritional requirements and supplementation should be done with veterinary guidance.

References

1. Donadelli RA, et al. "Owner-reported diet and health status in dogs: a cross-sectional study." PLOS ONE. 2022. PMID: 36082337.
2. Pion PD, Fascetti AJ. "Nutritional quality and variability in commercial pet foods." Veterinary Clinics of North America: Small Animal Practice. 2021. PMID: 34547527.