Published: June 2021 | Updated: September 2022
When it comes to reading labels on horse feed and supplements, L-glutamine is an ingredient that performance horse owners may automatically skip over in favor of better known ingredients such as certain vitamins, minerals, or possibly herbs.
However, L-glutamine is the most abundant and versatile amino acid (i.e., building block of protein) found in the horse’s body, making up over 60% of skeletal muscle and 20% of the body overall.
This amino acid is especially important when it comes to a horse’s metabolism, digestive tract, internal pH balance, as well as nitrogen exchange between bodily tissues.
It also serves as fuel for both skeletal and smooth muscle during every day movement, exercise, and performance.
With all of that said, L-glutamine is definitely a nutrient we should be paying attention to, especially since it can become depleted during times of stress–whether that be digestive stress, illness, or intensive training.
Under normal circumstances, a horse’s body produces a sufficient amount of L-glutamine, but during times of stress, the levels of L-glutamine being naturally produced may not be enough. Likewise, L-glutamine may be depleted by other conditions such as stomach or hindgut ulcers, malnutrition, or infection. These are all times when supplementation may be necessary.
*It should be noted that equine supplement labels may also use the broader term, glutamine, in some instances, but they are virtually the same thing, and therefore, can are often used interchangeably.
L-Glutamine and Horse Muscle Recovery
L-glutamine is produced in the muscles and is extremely important when it comes to muscle recovery. In fact, one of its functions is helping to decrease muscle soreness through improved muscle repair and glycogen repletion.
During exercise, microscopic tears occur in the muscle tissue, which is normal. However, the size and severity of these tears will depend on the intensity of the exercise.
The body responds by sending satellite cells from outside the muscle fibers to the area of damage where they replicate, mature into grown cells, and attach themselves to the muscle fibers.
This forms new muscle protein strands and helps to relieve soreness. L-glutamine plays a role in this entire process, helping to repair muscle tissue after damage has occurred.
However, if exercise is intense or if the horse isn’t yet acclimated to the level of exercise, this can lead to increased risk of injury and impaired muscle recovery because the horse’s body may not be able to produce enough L-glutamine to keep up.
Also important in muscle recovery is L-glutamine’s function as the most important antioxidant molecule found in muscle cells.
Antioxidants help to remove potentially damaging oxidizing agents in the body and are especially important during times of stress or intense exercise. Likewise, L-glutamine provides nitrogen and carbon (aka, “fuel”) to many different types of cells and plays a part in the production of certain chemicals in the body, as well as glucose (sugar).
L-Glutamine’s Role in Equine Gut and Immune Health
L-glutamine is of special importance when it comes to gut health for horses, as it aids in maintaining tight junctions in the gut lining, rebuilding and repairing tissue, as well as reducing inflammation within the horse digestive system.
The intestinal lining uses L-glutamine to create a strong surface for digestion and nutrient absorption, and studies in people have shown that both the small and large intestine can metabolize large amounts of glutamine supplied by the diet or from the bloodstream.
It’s also important to note that the horse’s digestive system houses more than 70% of their immune system, and it’s because of this that gut and immune health are closely tied.
The lining of the stomach and intestine act as the body’s defense mechanism against toxins and disease. However, when this lining breaks down, ulceration can occur. This not only causes discomfort, but allows toxins to leak into the blood system, leading to a host of other possible issues as well. If you suspect ulcers in your horse at all, L-glutamine should be supplemented in order to help repair the mucosal lining.
Additionally, L-glutamine is a precursor for glutathione--a vital antioxidant that protects the horse immune system cells from damage. In fact, the rate at which L-glutamine is used by immune cells is similar or greater than the rate of glucose usage.
Studies have also shown that L-glutamine is an essential nutrient for lymphocyte (a type of white blood cell) proliferation and cytokine (proteins which help to fight off pathogens) production.
Signs That Your Horse is Deficient in L-Glutamine
Insufficient levels of L-glutamine can negatively impact your horse in several ways.
One, recovery time after intense exercise can be delayed or impaired, and two, the intestinal villi–the small fingerlike projections which aid in digestion and absorption of nutrients–are negatively impacted. This is known as villous atrophy and it occurs when inflammation as well as normal wear-and-tear occurs in the cells in the intestinal lining.
A diet that is insufficient in L-glutamine may also lead to:
- Atrophy of the intestinal villi;
- Ulceration in the stomach and/or large colon;
- Increased intestinal permeability;
- Intestinal tissue necrosis;
- Digestive complications; and/or
- Poor nutrient absorption.
When additional L-glutamine is provided via supplementation, this serves to strengthen the villi and also maximize the surface area available for nutrient absorption along the small intestine, helping to improve both gut and immune health in your horse.
How to Supplement Glutamine for Horses
L-glutamine is sometimes included in muscle recovery supplements, but because of L-glutamine’s well-documented effects on gut health, it’s commonly included in high quality probiotics for horses as well.
In fact, L-glutamine is one of the leading ingredients in all of Fullbucket’s probiotic products. For example, one scoop of Equine Probiotic Pellets contains 1250 mg of L-glutamine and one dose of our Equine Probiotic Paste contains 2500 mg of L-glutamine.
When paired with large numbers of the beneficial bacteria in probiotics, the addition of glutamine for horses may have an even greater positive effect on equine gut health, which is important in both preventing and treating a variety of GI-related issues.
Glutamine: Metabolism and Immune Function