Oxidative Stress in Horses with Gastric Ulcers | BioStar US

Oxidative Stress in Horses with Gastric Ulcers

As many of you know, I am rather obsessed with the GI tract. From as far back as 2007 when I started BioStar, I have always focused on the health of the equine gut.

My obsession probably began in 1981 when my seven-year-old off-the-track thoroughbred Cappy colicked and foundered. After several months of veterinary and farrier intervention without results, and the horse’s constant pain, I had to put him down.

If I had only known then what I know now….

Staying up to date with research

Looking back, it’s amazing how much more we know now about the equine GI tract than when I lost Cappy. Even since BioStar’s founding, the research and understanding of the GI tract of horses has grown exponentially.

There’s still so much we don’t know, yet the advances in equine GI tract research and veterinary care cannot be overstated.

Several days ago, I headed down the oxidative stress rabbit hole and came upon a January 2020 study published in the Journal of Equine Veterinary Science highlighting oxidative stress in horses with gastric ulcers.1

What is oxidative stress?

Oxidative stress occurs when there are too many free radical oxygen molecules and not enough antioxidants to neutralize them. This imbalance results in cell and tissue damage.

Free radicals are molecules that are missing an electron from their outer shell, which makes them unstable. They try to steal an electron from other molecules wherever they can, which causes damage to surrounding cells.2

Oxygen free radicals are the products of cellular metabolism, and are known as reactive oxygen species (ROS). They are unstable, highly reactive, and play a significant role in inflammation.

Under normal conditions, antioxidants neutralize free radicals by scavenging free radicals, thereby reducing or helping to prevent damage caused by oxidation.

The goal is not to eliminate free radicals entirely, because low levels are actually essential, as they play a role in cell-to-cell signaling, gene function, and enzymatic activity.

While excess ROS can be harmful, a healthy horse naturally maintains a balance between antioxidants and free radicals.

What are antioxidants?

Antioxidants are substances that remove potentially damaging oxidizing agents in a living organism.

Antioxidants benefit the body by donating one of their own electrons to the unstable ROS, thereby stabilizing that molecule and neutralizing its negative effects. Importantly, antioxidants can do this without becoming unstable free radicals themselves.3

Examples of antioxidants include vitamin C, beta carotene, vitamin E, selenium, zinc, copper, flavonoids, manganese, nitric oxide, fulvic and humic acids, curcumin, and polyphenols.

Free Radicals, Antioxidants & Oxidative Stress | BioStar US

Which came first, the chicken or the egg?

From the Journal of Equine Veterinary Science study:

… oxidative stress is evident in horses with equine gastric ulcer syndrome (EGUS). Consequently, antioxidant therapy may be indicated for supportive treatment protocol of diseased horses.1

We cannot yet ascertain whether free radicals and oxidative stress play a role in ulcer formation or are the result of ulcer formation. We do know that oxidative stress is present in horses with gastric ulcers, and antioxidant support would be a beneficial therapy.

Should I add more vitamin C to my horse’s diet?

Vitamin C is a well-known antioxidant. Horses, unlike humans, can make their own vitamin C.

When supplementing with vitamin C, the horse may start producing less of their own. When you decide to stop supplementing vitamin C, it’s important to reduce the amount slowly, so the body has time to reestablish endogenous levels of this vitamin.

Foods that supply antioxidants for horses

Real foods – not food byproducts – provide antioxidants in varying amounts.





Indian Gooseberry or Amalaki

  • Fresh forage supplies vitamin E. Your horse will need 8-10 hours on pasture to get enough vitamin E.
  • Alfalfa provides beta carotene, vitamin C and E, flavonoids and phenols.
  • Chia seeds provide quercetin, a flavonoid that is a highly effective antioxidant.
  • Sunflower seeds contain phenolic acids and flavonoids, plus vitamin E.
  • Pumpkin seeds provide flavonoids and phenolic acids, plus zinc and magnesium.
  • Cinnamon provides flavonoids and other antioxidants that specifically inhibit fatty acid oxidation. Note: cinnamon is NOT show-safe.
  • Turmeric contains curcumin, which exhibits both antioxidant and anti-inflammatory properties.
  • Spirulina provides carotenoids, vitamin E tocopherols, flavonoids and phycocyanins. Some studies have shown that spirulina can improve oxidative stress markers.4
  • Apples and carrots: Apples provide quercetin, and carrots provide beta carotene. For non-metabolic horses, adding some apple slices and carrots to feed or as a treat provides another measure of antioxidant support.
  • Kale provides beta-carotene, vitamin C, flavonoids and polyphenols.
  • Medicinal mushrooms: Reishi ranks as the top medicinal mushroom with antioxidant properties, followed by turkey tail, hemlock varnish shelf, and lion’s mane. These mushrooms also supply manganese, zinc, copper, and glutathione.
  • Indian gooseberry (amalaki) supports production of nitric oxide as an antioxidant and is one of the Rasayana plants in Ayurvedic medicine.
  • Shilajit has high concentrations of fulvic and humic acids, which act as antioxidants and anti-inflammatory compounds.

How about hay for vitamin E?

Antioxidant vitamin E in hay breaks down very quickly after the hay is baled. A lot more horses are presenting with vitamin E deficiency than in the past, partly due to the reduction of pasture time and fresh forage that horses have access to.

Relying on hay to provide the necessary vitamin E may not be the best practice. Always get a complete blood count (CBC) done once a year by your vet to make sure vitamin E levels are normal.

The selenium, copper, and zinc in hay may be more stable than its vitamin E content. Getting a hay analysis is a good practice for all barns, not just for horses with metabolic issues.

Free Radicals, Antioxidants & Oxidative Stress | BioStar US

Supporting your horse with antioxidants

Research has shown that it’s important to make sure your horse is adequately supplied with antioxidants and antioxidant-supportive foods.

BioStar offers many antioxidant-rich supplements:

Optimum EQ 2.0, Optimum EQ 2.0 Senior, Optimum GI, Optimum HW, Circuvate EQ, Hedgerow GI, Thera Calm EQ, Adaptor EQ, Quantum EQ, Sunn-E 1000, Chi Tonic EQ, Alixir EQ paste, Zen-Max paste, Tri-Gard EQ paste

Optimum EQ 2.0 | BioStar US
Circuvate EQ for horses | BioStar US
Optimum EQ Senior 2.0 bag
Hedgerow GI by BioStar US
Optimum GI - Multivitamin and Mineral with gastric support | BioStar US
Thera Calm EQ for horses | BioStar US
Optimum HW Healthy Weight for Horses | BioStar US
Adaptor EQ | BioStar US
Quantum EQ | BioStar US

Sunn-E 1000 Vitamin E for Horses | BioStar
Zen-Max equine calming supplement from BioStar

Chi Tonic EQ by BioStar US
Tri-Gard EQ


1- https://www.sciencedirect.com/science/article/abs/pii/S0737080619306021
2- https://health.clevelandclinic.org/free-radicals/
3- https://www.unm.edu/~lkravitz/Article%20folder/Antioxidants.html
4- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5274660/#B39

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