Can dogs and cats effectively digest plant-based foods?

Hooray for yet further research by the wonderful Prof Andrew Knight tackling more important issues about the digestibility of plant-based diets in dogs and cats, and it is ALL positive!

Prof Andrew Knight's words - 

"One of the most common arguments against feeding dogs and cats vegan or plant-based diets is that they can't digest plant ingredients because they evolved from carnivores.

This perception isn't helped by the number of pet foods marketed as grain-free, which adds to confusion and leaves people wondering whether grains are okay. So one of research pieces I’ve been working on is a review of what the studies in this field demonstrate.

This study, now published in the peer-reviewed journal Animals, reviews 31 studies that examined how well vegan, vegetarian and plant-based diets and their main ingredients are digested by dogs and cats.

Digestibility is important because it tells us how effectively animals can absorb and use the nutrients in their food. The review found that modern, nutritionally sound vegan diets are generally well digested by both dogs and cats, with digestibility broadly comparable to conventional meat-based diets.

I say ‘modern’ because as with any diet, nutritional formulation matters.

But ingredients such as wheat gluten, faba bean protein, peas, lentils, chickpeas, rice protein, potato protein and quinoa have all been shown to be highly digestible.

Summary from latest research (May 2026 Knight et al)

Digestibility is one of the key factors used to evaluate whether a diet can adequately provide nutrients to an animal.

Concerns have long existed that plant-based pet foods may be less digestible than conventional meat-based diets, particularly in cats due to their obligate carnivorous physiology. 

A 2026 review by Prof Andrew Knight sought to evaluate this claim by analysing the available evidence on the digestibility of vegan and vegetarian diets and plant-derived protein sources in dogs and cats, including the digestibility of microbial fermentation protein Feedkind (used in MicroBell dry food and soon in BioBuddy).

The review included 31 studies that assessed true digestibility, and amino acid digestibility.

𝗔𝗺𝗼𝗻𝗴 𝘁𝗵𝗲 𝘀𝘁𝘂𝗱𝗶𝗲𝘀 𝗲𝘃𝗮𝗹𝘂𝗮𝘁𝗶𝗻𝗴 𝗰𝗼𝗺𝗽𝗹𝗲𝘁𝗲 𝘃𝗲𝗴𝗮𝗻 𝗼𝗿 𝘃𝗲𝗴𝗲𝘁𝗮𝗿𝗶𝗮𝗻 𝗱𝗶𝗲𝘁𝘀, 𝗱𝗶𝗴𝗲𝘀𝘁𝗶𝗯𝗶𝗹𝗶𝘁𝘆 𝘃𝗮𝗹𝘂𝗲𝘀 𝘄𝗲𝗿𝗲 𝗰𝗼𝗻𝘀𝗶𝘀𝘁𝗲𝗻𝘁𝗹𝘆 𝗵𝗶𝗴𝗵. 

In all five studies that measured digestibility of complete plant-based diets, it exceeded:

• 80% for dry matter
• 85% for organic matter
• 80% for crude protein
• 89% for fat
• 88% for nitrogen-free extract
• 86% for energy

In some studies, animal-based diets showed slightly higher digestibility for certain parameters, whereas in others, plant-based diets demonstrated equal or superior digestibility.

Current evidence suggests that a variety of plant-based protein sources—including soya, legumes, pulses, grains, and fermentation-derived proteins—are highly digestible in dogs and cats, although feline studies remain limited.

While digestibility may vary depending on ingredient type, processing method, and nutrient composition, plant-based protein sources generally demonstrate digestibility values comparable to animal-based proteins.

Even when lower digestibility was reported for specific nutrients, overall nutrient utilisation remained high.

These findings support the use of properly formulated vegan and vegetarian pet diets and challenge the assumption that they are inherently less digestible than conventional meat-based diets.

Further research, particularly in cats and under real-world feeding conditions, is still needed so if you have a cat, please help the research here.

Listen to Dr Arielle below speaking about the digestibility of bacterial fermentation protein that is added to MicroBell dog food with this enhanced digestibility adding to the overall health of dogs.

Read about Parcours athlete Collie Ninja who gets all of his energy from fermentation protein MicroBell

MicroBell Innovation Celebration Here

We cannot wait for UK's very first fermentation protein BioBuddy Cold-Pressed Superfood to launch very soon!

“When nutrition is done right, you don’t necessarily notice it working — you just notice your dog thriving. No noise, no stress, no vet appointments. To benefit our environment and farmed animals too is a massive bonus!”

- Dr Arielle Plant Powered Vet 

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