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Wheat, glyphosate, zonulin & leaky gut in horses, is there evidence?

Updated: May 23, 2023

Are there wheat products in your equine feed or supplements?

Are there interactions between glyphosate (RoundUp) and gluten? It has been said that on their own, neither would induce ulcers or leaky gut but when combined together the result was of the latter, among many other illnesses and conditions in humans, animals and even in our plants!

"the usage of glyphosate on WHEAT in the U.S. has risen sharply in the last decade"... "glyphosate residues in WHEAT and other crops are likely increasing recently due to the growing practice of crop desiccation just prior to the harvest"...

"glyphosate, patented as an antimicrobial has been shown to disrupt the gut bacteria in animals, preferentially killing beneficial forms and causing an overgrowth of pathogens"... (dysbiosis)

"glyphosate's known suppression of CYP enzyme activity in plants and animals..."

"show that glyphosate is associated with an overgrowth of pathogens along with an inflammatory bowel disease in animal models"...

With an established relationship to gut dysbiosis, or disruption of gut microbial balance due to exposure to glyphosate, let's explore how wheat fits into the equation. Wheat is a grain produced for human consumption and wheat by-products are used for animal feed and supplementation products, including for horses. Gliaden is a major component of wheat gluten and can be found in other grains such as barley, rye and triticale. Gliaden has been proven to activate zonulin signaling in humans "irrespective of the genetic expression of autoimmunity, leading to increased intestinal permeability to macromolecules" (Drago).

Zonulin is a protein that was discovered in 2000 by Dr. Allessio Fasano, a medical doctor, world renowned pediatric gastroenterologist and research scientist. Zonulin is a mammalian protein that modulates the barrier of cellular tight junctions of the digestive tract. Through human research, two undeniable factors have contributed to tight junction permeability...gluten and dysbiosis. "Alarmingly, this chemical (glyphosate) is ten times more potent than gluten at the zonulin pathway, adding to the breakdown of the tight junction." (Dolan, RN).

"Importantly, zonulin remains the only modulator of intracellular tight junctions expressed so far that can affect gut function and health and associated immune response and so it is widely investigated." (Gardner BSc, MRes, PhD).

So zonulin has been found in humans, has it been found in other mammals as well or is this protein human specific? Zonulin has been studied in non-human primates (Rhesus Monkeys), murine specimens (rats and mice), rabbits, porcine (pig) subjects. (4, 5, 6, 7.)

Now, consider the recent concerns that horses experience leaky gut syndrome. The equine market has developed supplement after supplement to try and heal this condition, yet it still persists. We see increases of equine allergies, EPM infections, systemic inflammation and more. When one looks at the ingredients of many, many feeds and supplements it is easy to observe the prevalence of wheat by-products (wheat bran, wheat middlings, etc) as an ingredient, even ones marketed to address leaky gut specifically. If this same gluten-dysbiosis-gut permeability process is the same in horses and other mammalian species, by feeding wheat on a continual basis through daily feed and supplementation, we are effectively delivering a double-edged attack on the integrity of our horse's digestive tract. With the evidence discussed in this article, it is the belief of the author that research into identifying zonulin in the equine, its mechanisms of action and activations of pathways to maintaining tight junctions of the digestive tract, and its relationship with wheat in order to improve equine health, performance and welfare be further researched.

-Authored by Ashley Teasley on March, 2, 2020 with further edits January 13, 2021.


1. Gardner, BSc, MRes, PhD, Dr. Aaron. "How Zonulin Causes Leaky Gut And Autoimmunity - Gene Food". Gene Food, 2020, Accessed 13 Jan 2021.

2. Dolan, RN, Jane K. "Zonulin, Gluten, Glyphosate And Tight Junctions | Marion Institute". Marion Institute | Medicine From A Different Perspective., Accessed 13 Jan 2021.

3. Drago, Sandro & Asmar, Ramzi & Pierro, Mariarosaria & Clemente, Maria & Tripathi, Amit & Sapone, Anna & Thakar, Manjusha & Iacono, Giuseppe & Carroccio, Antonio & D'Agate, Cinzia & Not, Tarcisio & Zampini, Lucia & Catassi, Carlo & Fasano, Alessio. (2006). Gliadin, zonulin and gut permeability: Effects on celiac and non-celiac intestinal mucosa and intestinal cell lines. Scandinavian journal of gastroenterology. 41. 408-19. 10.1080/00365520500235334. Accessed 13 Jan 2021.

5. Karen E. Thomas, Anna Sapone, Alessio Fasano, Stefanie N. Vogel. "Gliadin Stimulation of Murine Macrophage Inflammatory Gene Expression and Intestinal Permeability Are MyD88-Dependent: Role of the Innate Immune Response in Celiac Disease." The Journal of Immunology February 15, 2006, 176 (4) 2512-2521; DOI: 10.4049/jimmunol.176.4.2512. Accessed 13 Jan 2021.

6. Asmar, Rahzi El et al. "Host-Dependent Zonulin Secretion Causes The Impairment Of The Small Intestine Barrier Function After Bacterial Exposure". Basic-Alimentary Tract, vol 123, no. 5, 2002, pp. 1607-1615., doi: Accessed 13 Jan 2021.

7. Modina, Silvia Clotilde et al. “Nutritional Regulation of Gut Barrier Integrity in Weaning Piglets.” Animals : an open access journal from MDPI vol. 9,12 1045. 29 Nov. 2019, doi:10.3390/ani9121045. Accessed 13 Jan 2021.

Additional references not cited in this article:

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