The gastrointestinal tract (GIT) is a very special organ and performs a number of special functions
including: breakdown of foodstuffs, destruction of pathogenic organisms and substances, absorption of
nutrients, production of nutrients, provision of energy sources for cells lining the intestine, providing a
barrier between what is in the GIT and what is on the other side of the GIT. Barrier function is crucial –
when barrier function is compromised pathogens enter into the body from the GIT.
Nutraceutical ingredients, including but certainly not exclusively prebiotics and probiotics, are proving
beneficial and perhaps essential in maintaining barrier function. The GIT barrier is comprised of two
structural components: a single layer of intestinal epithelial cells (IECs) that are tightly held together by
networks of numerous junctional proteins forming a nearly impervious barrier when healthy; and a layer
of peptide and antibiotic-rich mucous that lies ‘above’ the IECs. Various stressors, which can act from
within the GIT or from the horse and its environment, are the biggest challenge to maintaining healthy
barrier function. Compromised barrier function results in a leaky gut, and the range of such conditions is
termed leaky gut syndrome (LGS). Features can include one or more of: gastric ulcers, intestinal
inflammation, intestinal leakiness (manifest as diarrhea or constipation). These conditions are typically
associated with impaired nutrient absorption, compromised immune function and failing health.
We are learning that nutraceuticals can play a number of different and important roles in maintaining
the mucosal and the IEC barriers in the face of GIT and environmental stressors (i.e. unusual foods, heat,
exercise, confinement, transport, new surroundings, rough handling). Some act on the stomach to help
maintain the gastric mucosa, reducing the prevalence and severity of gastric ulcers. Others provide
nutrients specific to the needs of the IECs and the mucosal layer. Others yet provide nutrients to the
microbiota within the GIT, helping beneficial (commensal) bacteria proliferate while controlling
populations of pathogenic bacteria. And others appear to provide direct benefit to IECs by providing
molecules, or stimulating beneficial microbes to produce molecules, that are used by IECs to maintain
tight junctions between cells. Together, good nutrition working with the right nutraceuticals, can help
maintain a healthy GIT under all conditions and help restore a leaky GIT.
See the May-June issue of Equine Wellness Magazine for the first of a 3-part series on LGS in horses.