-Katey Campbell, KC Equine Wellness
We already know in human nutrition that vegetable oils like canola, soy, corn, and generic “vegetable oil blends” are some of the most inflammatory substances we can consume. They’re industrial seed oils extracted with high heat, chemical solvents, bleaching, and deodorizing, leaving behind unstable fats that damage the gut, stress the liver, disrupt hormones, and increase oxidative stress. If these oils are harmful for humans, who have far more dietary flexibility, they are even more problematic for horses whose digestive systems are designed for forage, fiber, and naturally occurring fats, not chemically altered industrial oils. In horses, vegetable oils are still commonly recommended, yet these recommendations are based on outdated ideas rather than equine biology.
These oils are extremely high in omega‑6 fatty acids, which drive inflammation, irritate the gut lining, and increase oxidative stress throughout the body. Because they are chemically extracted and highly refined, they are already oxidized before they ever reach the feed room, meaning the horse’s liver must work overtime to process them. Instead of supporting health, vegetable oils add metabolic stress, disrupt cell membranes, and contribute to systemic inflammation that affects joints, hooves, hormones, digestion, and overall comfort.
One of the most common recommendations is using vegetable oil for ulcers because of its “prostaglandin effect,” but the prostaglandins produced from omega‑6 fats are inflammatory, not healing. While oil may temporarily coat the stomach, internally it increases inflammation, irritates the gut, disrupts microbial balance, and adds oxidative load, exactly the opposite of what an ulcer‑prone horse needs. True ulcer support comes from reducing inflammation, improving forage quality, supporting the hindgut, and using anti‑inflammatory omega‑3 sources, not industrial seed oils.
Vegetable oil is also recommended for metabolic horses because it is “low glycemic,” but low glycemic does not mean metabolically supportive. These oils do not improve insulin sensitivity, lower blood glucose, or support metabolic pathways. Instead, they worsen insulin resistance by increasing inflammatory cytokines, disrupting cell membrane function, and adding oxidative stress. A metabolic horse needs anti‑inflammatory, omega‑3‑rich support not industrial oils that push the body further into dysfunction.
Another common use is for weight gain, yet if a horse cannot gain weight, the issue is almost always related to digestion, hindgut imbalance, malabsorption, mineral deficiencies, chronic inflammation, or liver stress. Adding vegetable oil does not fix any of these root causes. Instead, it burdens the liver, worsens leaky gut, increases oxidative stress, and disrupts microbial balance, making it even harder for the horse to digest and absorb nutrients. Weight gain comes from improving digestion, balancing minerals, supporting the hindgut, and reducing inflammation, not adding inflammatory calories.
Vegetable oil is not a health food, not for humans, and not for horses. It’s an industrial product that disrupts metabolic function, increases inflammation, stresses the liver, and damages the gut, and the fact that it’s still recommended in the equine world reflects outdated nutrition models rather than true equine biology. Horses don’t need industrial seed oils; they need biologically appropriate fats, whole‑food support, balanced minerals, and nutrition that aligns with how their bodies are designed to function.
If you’re looking to support your horse with healthy fats, choose whole‑food sources such as flax, hemp, chia, or even a small amount of stabilized rice bran. These provide naturally occurring omega‑3s and anti‑inflammatory compounds without overwhelming the digestive system. But even with whole foods, more is not better, 2 tablespoons to ¼ cup is plenty for most horses. It’s important to remember that horses do not have a gallbladder, which means they are not designed to process large amounts of fat at one time. Their liver is solely responsible for producing bile, and it already works hard managing detoxification, metabolism, and nutrient processing. Overloading the system with excessive fat — even “healthy” fat, can stress the liver, slow digestion, and create more problems than it solves.
Balance is key!