Horses naturally produce molecules called reactive oxygen species (ROS) when their bodies turn feed and forages into energy. When they run, jump, or work hard, their bodies create even more of these unstable molecules. If too many ROS build up within the body, they cause oxidative stress, a form of cellular degradation that damages healthy tissues and weakens the body.

To defend against oxidative stress, horses rely on a powerful team of antioxidants, including vitamin E, glutathione peroxidase, and polyphenols.

Vitamin E: Protecting Cell Membranes in Horses

Every cell in a horse’s body is surrounded by a flexible outer wall called a cell membrane. This membrane is made of fats susceptible to the damaging effects of ROS.

When ROS attack these fats, a destructive chain reaction known as lipid peroxidation is triggered. Lipid peroxidation weakens the cell membrane, prevents vital nutrients from moving in and out, and can ultimately cause the cell to rupture and die.

Vitamin E is a fat-soluble nutrient that situates itself within the cell membrane. It acts like a shield, disarming ROS before they can destroy the surrounding fats.

In intensely exercised horses, adequate vitamin E levels keep cell membranes intact, especially in high-use areas such as skeletal muscles and red blood cells that bear constant stress.

Glutathione Peroxidase: Whole-Body Protection

While vitamin E helps protect cell membranes, an enzyme called glutathione peroxidase works in other parts of the body, including fluid both inside and outside of cells. To do its job, glutathione peroxidase relies on the trace mineral selenium.

Glutathione peroxidase neutralizes ROS by converting them into harmless byproducts before they can spread. This protects several major body systems and tissues, including:

• Muscles: Cleans up toxic byproducts generated during heavy exercise so muscle cells can recover quickly.
• Liver and kidneys: Helps filter out cellular waste and prevents metabolic damage in key organs.
• Cardiovascular system: Operates inside red blood cells to protect them as they carry oxygen throughout the body.

Together, glutathione peroxidase and vitamin E make a formidable defense team. Glutathione peroxidase destroys ROS before they reach the cell membrane, while vitamin E stops any ROS that manage to slip through.

Polyphenols: Additional Antioxidant Support

While vitamin E and glutathione peroxidase are well-known antioxidants, polyphenols are a newer addition to the landscape. These natural compounds are found in plants, berries, and herbs.

When horses consume polyphenols, these compounds offer extra protection in two ways:

(1) they sweep through the body and disarm floating ROS on contact; and (2) they help calm the body’s inflammatory signaling.

In performance horses polyphenols help dial down the body’s inflammatory response, which can boost comfort and ease of movement and can shorten recovery time between training sessions.

Take-Home Message

As we ask more of horses athletically, it is important that we support them nutritionally, providing high-quality forages and concentrates as well as targeted supplementation designed to protect tissues and foster recovery.