Media release

From: PLOS

Plant-based dog foods not nutritionally complete, but may suffice with supplements

In U.K. study, no meat-based nor veterinary dog foods met all nutritional guidelines either

In a study of dog foods sold in the U.K., plant-based foods did not fully meet nutritional guidelines – but meat-based and veterinary foods also fell short of being nutritionally complete. Rebecca Brociek of the University of Nottingham, U.K., and colleagues present these findings in the open-access journal PLOS One on September 3, 2025.

While dogs are omnivores that can derive nutrition from meats and plants, interest in entirely plant-based dog diets is growing among owners. Prior research has suggested that such diets may be linked to micronutrient deficiencies. However, many dog foods, including plant-based products, are labeled as being “complete,” meaning they should supply all the macro- and micronutrients a dog needs, according to the U.K.’s Food Standards Agency.

Due to limited research, the nutritional soundness of complete plant-based dog diets has been unclear. To help clarify, Brociek and colleagues analyzed the nutrient content of 31 dry dog foods sold in the U.K. and labeled as “complete,” including 19 meat-based foods, 6 plant-based, and 6 veterinary foods designed to be low in protein for dogs with kidney conditions.

The meat- and plant-based foods had similar nutritional profiles when it came to proteins and amino acids, but the plant-based foods typically did not meet European Pet Food Industry Federation (FEDIAF) guidelines for iodine and B-vitamin levels for adult dogs. However, the researchers note, these nutrients can easily be given to dogs as supplements, or more likely, changes to formulation should be managed by the pet food manufacturers.

None of the foods met FEDIAF standards for all nutrients for adult dogs. Out of 31 products tested, all met guidelines for vitamin D levels, but only 17 met guidelines for amino acids, 5 for minerals, and 4 for B-vitamins. In addition, most of the veterinary foods did not meet guidelines for essential amino acids, which dogs cannot create themselves and must obtain from food.

These findings could help inform dog owners’ dietary choices for their pets. Future research could help address some of this study’s limitations, such as by considering nutritional requirements of younger dogs that are still growing and accounting for biochemistry in the digestive system that might impact nutrient levels actually absorbed from a complete food.

Rebecca Brociek adds: “Many of us assume that dogs need meat to stay healthy, but in fact, what they really need are the right nutrients. Similar studies have been undertaken comparing plant-based dog foods in Brazil and Canada and we wanted to compare those available in the U.K. What I found was surprising - these foods stacked up more closely to meat-based diets than expected, with all showing some nutritional gaps. With more studies on plant-based pet foods emerging every year, I’m excited to help move this conversation forward.”