Can Whole Food Nutrition Combat Leaky Gut in Horses?

New University of Guelph study explores the gut-health potential of activated hemp seed powder

Could a simple, nutrient-rich feed ingredient hold the key to managing one of the most elusive conditions in equine health? A new research initiative at the University of Guelph aims to shed light on a little-understood and potentially widespread condition in horses: leaky gut syndrome. Dr. Wendy Pearson, Associate Professor in the Department of Animal Biosciences, is leading a study that could sow the seeds for innovative nutritional strategies to support equine gut health using activated hemp seed powder.

Leaky gut syndrome, or increased intestinal permeability, occurs when the tight junctions in the gut lining become compromised, allowing substances that should remain in the digestive tract—such as toxins, bacteria, and undigested food particles—to leak into the bloodstream. In humans, this condition has been linked to systemic inflammation, allergies, irritable bowel and colitis. In horses, however, the science is still in its infancy.

“We’re really just beginning to understand what leaky gut looks like in horses,” says Pearson. “There are very few peer-reviewed publications on the topic in equines. Most of what we know comes from human and non-equine animal models.”

Leaky gut may contribute to a range of chronic, low-grade inflammatory conditions in horses, including poor performance, allergies, and joint issues like osteo-arthritis. Until recently, researchers lacked the tools to measure gut permeability in horses with precision.

Now they are able to use a compound called iohexol—a safe, inert contrast agent used in pediatric medicine—to detect changes in gut permeability. “Iohexol is just slightly too large to pass through healthy tight junctions,” Pearson explains. “So when we see it in the bloodstream after inducing stress, we know those junctions have opened.”

Stressors and diet are suspected contributors to leaky gut in horses. One study from Michigan State University also linked NSAID’S (non-steroidal anti-inflammatory drug) to increased gut permeability, though it remains unclear whether the drugs themselves or the ulcers they cause are to blame. Transport stress followed by moderate exercise has been shown to temporarily increase gut permeability, though the long-term effect of repeated stress is still unknown.

Pearson’s team will explore whether activated hemp seed powder can help protect the gut barrier and reduce inflammation. Hemp seed meal is nutrient-dense and has shown promise in other species for its ability to positively influence the gut microbiome and reduce inflammatory markers.

“What makes this product exciting is that it’s closer to a whole food than a refined nutraceutical,” says Pearson. “The sprouting process enhances its nutritional profile, and early lab work suggests it may have anti-inflammatory effects.”

The study will not only measure gut permeability but also analyze joint fluid and blood samples for inflammatory biomarkers. If successful, the research could open the door to new management strategies for horses facing chronic inflammation or performance issues.

In human studies, there’s a surprising trend: the more physically fit a person is, the more likely they are to experience gastrointestinal hyperpermeability during exercise. Elite athletes often show a more pronounced gut response to physical exertion compared to less active individuals. Whether this same relationship exists in horses is still unknown, but Pearson announces they have an imminent research project to address that question.

Due to a former study, it is known that transport stress followed by moderate intensity exercise is sufficient to increase permeability of the gut for a short period of time.

“We can’t say exercise causes leaky gut in horses,” Pearson cautions. “But we do know it contributes to short-term changes in gastrointestinal hyperpermeability. What we need to understand is how repeated exposure and fitness levels factor into that equation.”

Pearson underscores that the goal is not to eliminate stressors like exercise, but to better understand how to support horses through them. “We’re trying to understand how to support them through informed management and nutrition.” Gut health is a central concern in equine care.

“Gut health is foundational to a healthy horse,” explains Pearson. “The microbiome plays a critical role in immune function, and the gut lining is the first line of defense against pathogens. If we’re putting horses in situations that compromise that barrier, we need to know about it.”

Until more research is available, horse owners and veterinarians are encouraged to stick to the fundamentals: a forage-based, balanced diet, and as much turnout as possible. “Ideally, horses should have 24/7 access to turnout,” says Pearson. “That’s not just a personal bias—it’s backed by evidence.”

As the science evolves, Pearson hopes research findings will lead to informed decisions in equine nutrition and training. “This is about generating knowledge that leads to education and education is what ultimately transforms how we care for our horses.”

Interested in learning more about equine gut health? Sign up for Equine Guelph’s short online course: Gut Health & Colic/Ulcer Prevention at TheHorsePortal.ca and the 12-week online Equine Nutrition Course at University of Guelph.

Reference:

https://pubmed.ncbi.nlm.nih.gov/36210653

McGilloway M, Manley S, Aho A, Heeringa KN, Lou Y, Squires EJ, Pearson W. The combination of trailer transport and exercise increases gastrointestinal permeability and markers of systemic inflammation in horses. Equine Vet J. 2023 Sep;55(5):853-861. doi: 10.1111/evj.13888. Epub 2022 Nov 9. PMID: 36210653.

Notes to Editor:

Equine Guelph is the horse owners’ and care givers’ Centre at the University of Guelph in Canada. It is a unique partnership dedicated to the health and well-being of horses, supported and overseen by equine industry groups. Equine Guelph is the epicentre for academia, industry and government – for the good of the equine industry as a whole. For further information, visit www.equineguelph.ca.

Story by: Jackie Bellamy-Zions

Photos: (images available upon request)

Photo Credit: stock photo & YouTube video thumbnail

Photo Caption: Dr. Wendy Pearson, associate professor at the University of Guelph, discusses new research on leaky gut syndrome in horses

Web Link(s):

Story web link: https://thehorseportal.ca/2025/08/can-whole-food-nutrition-combat-leaky-gut-in-horses/