Plant ingredients in dog food – what does recent research say?

The views of dog owners about plant-based pet diets are often highly polarized, with some strongly in favor – often reflecting their own dietary preferences – while others retain a marked preference for meat- based diets. Using current evidence to understand the possible advantages of plant-based ingredients should provide vital information for all sides of this discussion.

The plus sides of plants

Plant dietary ingredients, known as phytonutrients, encompass dietary fibers, polyphenols, and carotenoids. Although not essential for dogs, they can provide additional health benefits. Spinach, for instance, is a rich source of vitamins A, E and B1, as well as essential minerals like calcium and iron. Similarly, peas and carrots contribute valuable nutrients such as vitamin A and dietary fiber.

A growing body of research has highlighted the health benefits of phytonutrients for dogs. Recent canine studies have mirrored trends in human medicine by focusing on the gut microbiome and mental health.

Regulating the immune system and glucose levels

Green tea polyphenols were shown to have multiple benefits due to anti-inflammatory activity. A 2020 study by researchers at the College of Animal Science and Technology, China, looked at 16 healthy beagle dogs fed a high-fat diet. Dogs with tea polyphenols incorporated into their diet had decreased mRNA expression of inflammatory markers, as well as liver fat content and degeneration.

Another 2020 study investigated rosemary and/or basil as food fortification in dogs. It was concluded that a rosemary and basil leaf powder combination demonstrated potential in regulating blood glucose levels, suggesting a potential role in managing diabetes.

Plant ingredients and the microbiome

The effects of grape proanthocyanidins on gut microbiota and serotonin and cortisol levels were studied in healthy adult dogs at the University of Udine. Dogs given these proanthocyanidins had a higher abundance of various gut bacteria and increased serotonin levels, while cortisol didn’t differ.

Another study, run by the Hill’s Pet Nutrition team, examined a polyphenol-rich prebiotic bundle in healthy dogs and those with chronic gastroenteritis. This improved stool quality and modulated gastrointestinal inflammation and motility, highlighting benefits for canine gut health. Several previous studies have already shown that dietary interventions with this prebiotic fiber bundle have improved stool scores, shifted fecal microbial metabolism desirably, and increased fecal anti-inflammatory and antioxidant metabolites compared with control foods in dogs and cats.

Further research by Hill’s Pet Nutrition in 2022 on a fiber bundle investigated the effect on canine fecal metabolites and microbiota. 48 healthy dogs were used in the study and fed a control diet for 28 days, followed by the treatment food phase of 31 days. The addition of the fiber bundle appeared to increase bioactive metabolites of improved antioxidant and anti-inflammatory potency for health benefits and again shifted gut bacterial metabolism toward desirable sugar breakdown.

Another significant study from Hill’s Pet Nutrition, published in Animals in 2022, evaluated the impact of a diet supplemented with polyphenols, prebiotics and omega-3 fatty acids on dogs’ intestinal microbiota and anxiety-related biomarkers. This research, involving 40 dogs, found that diets rich in fish oil and a polyphenol blend, with or without tomato pomace, decreased plasma levels of anxiety-associated metabolites and favorably altered gut bacteria. These findings suggest that plant-based supplements could beneficially impact mental health markers in dogs.

Evolving research

Evidence of the benefits of adding plant ingredients to canine diets is increasing as studies become larger and better designed. As the research evolves, the role plant-based ingredients can play in dog diets becomes more apparent. This aligns with an increasing understanding of the complex relationship between diet, health and behavior in dogs.

The potential of plant-based diets, tailored to individual dogs’ needs, lies in their ability to enhance health and well-being through scientifically informed dietary choices. This approach aims to improve not only the physical health of dogs but also their overall quality of life.