Vegan dog food might not be such a radical idea after all. A comprehensive analysis of 31 commercial dog foods in the UK reveals that plant-based diets deliver nutritional profiles remarkably similar to their meat-based counterparts—though both fall short of perfection.
The study, published today in PLOS One by researchers at the University of Nottingham, tested everything from protein content to trace minerals in dry kibble across three categories: traditional meat-based foods, plant-based options, and specialized veterinary diets for dogs with kidney problems.
What they found challenges assumptions on multiple fronts. Plant-based foods weren’t nutritionally inferior to meat-based ones, as many pet owners fear. But neither were the traditional options as complete as their “nutritionally balanced” labels suggest.
Only five of the 31 tested foods met all mineral requirements. Just four satisfied B-vitamin guidelines. And here’s where it gets interesting: the most problematic foods weren’t necessarily the vegan ones.
The Veterinary Diet Surprise
Veterinary diets designed for dogs with kidney disease—purposefully low in protein—showed the most concerning deficiencies. Two-thirds failed to meet essential amino acid requirements, despite carrying medical credentials and premium price tags.
One veterinary food fell below guidelines for six out of eight essential amino acids tested. All four deficient veterinary diets lacked adequate threonine, an amino acid crucial for immune function and gut health.
“Veterinary diets, purposely low in crude protein, often have less than optimal essential amino acid composition,” noted lead researcher Rebecca Brociek.
The implications aren’t trivial. Dogs with chronic kidney disease already face metabolic challenges. Feeding them diets deficient in essential amino acids—the building blocks their bodies can’t manufacture—could compound health problems rather than solve them.
Meanwhile, plant-based foods performed surprisingly well in protein metrics, often exceeding meat-based options in branched-chain amino acids like leucine and valine. The researchers had hypothesized these would be lower in vegan formulations.
The Micronutrient Gap
Where plant-based foods stumbled was predictable territory for anyone familiar with human vegan nutrition: iodine and B-vitamins. Five of six plant-based foods contained inadequate iodine levels, mirroring deficiency patterns seen in vegetarian humans.
B-vitamin content also lagged in plant-based options, particularly B3, B9, and B12. Only 24% of all foods tested—regardless of protein source—met B-vitamin guidelines. But the plant-based foods consistently ranked lowest.
“Plant-based diets, when properly formulated, can be a healthy and viable alternative to meat-based options,” Brociek explained, adding that iodine and B-vitamin supplementation could easily address the gaps.
The iodine finding caught attention because it’s relatively simple to fix. The one plant-based food that met iodine requirements contained seaweed and dried algae—natural plant sources rich in the mineral.
Turns out, even meat-based foods weren’t immune to deficiencies. Over half of all tested foods, regardless of protein source, contained inadequate iodine levels. Seventeen of 30 foods failed this basic requirement.
The Bigger Picture
This research arrives as plant-based pet food sales surge alongside human dietary shifts. The number of self-declared vegans in the UK quadrupled between 2014 and 2019, creating what researchers call an “ethical dilemma” for pet owners: should they feed animals to their animals?
The study analyzed the nutritional reality behind marketing claims, testing 31 foods against European Pet Food Industry Federation guidelines. The scorecard was sobering: 55% met amino acid requirements, 16% satisfied mineral guidelines, and exactly zero foods passed every nutritional test.
What’s particularly striking is that compliance rates varied dramatically by nutrient category. All foods met vitamin D requirements, suggesting manufacturers have mastered some aspects of formulation while struggling with others.
The researchers acknowledge limitations. They tested only adult maintenance diets, not puppy or reproductive formulations where nutritional gaps could prove more serious. And with just six plant-based options available in 2022, the sample size reflected market reality more than research preference.
But the core finding remains: dogs are omnivores, and they need specific nutrients, not specific ingredients. Whether those nutrients come from chicken or chickpeas matters less than whether they’re present in adequate amounts.
The study stops short of feeding trials—the gold standard for proving long-term safety and health outcomes. Those experiments, involving months or years of controlled feeding, represent the next frontier in plant-based pet nutrition research.
For now, the message is cautiously optimistic. Plant-based dog food isn’t inherently inferior, but it’s not automatically superior either. Like any pet food, quality depends on formulation, not philosophy.
The study suggests that both plant-based and traditional dog foods can provide adequate nutrition, but neither category is universally superior. Plant-based diets may require B-vitamin and iodine supplementation, while some veterinary diets may need amino acid fortification. The key finding is that nutritional completeness depends more on careful formulation than protein source. Pet owners considering dietary changes should consult veterinarians and choose foods from manufacturers who conduct comprehensive nutritional testing, regardless of whether the primary protein comes from plants or animals.
Published in PLOS One, DOI: 10.1371/journal.pone.0328506