Quercetin is a flavonol that affects many bodily functions. We know that it’s anti-inflammatory and an antioxidant, but how can it specifically help the horse?
This newsletter will focus on the body systems and conditions that can be supported by supplementation with quercetin.
◆︎ Blood vessel support:
Quercetin helps support healthy blood vessels. It does this by reducing the insult to the linings of the vessels by reactive oxygen species (ROS).
Chronic ROS negatively affects the circulatory system health. There are many causes for the development of ROS, which can then attack the linings of the blood vessels. These can include elevated insulin levels, insufficient hormones as the horse ages, or an environment that continually challenges the horse. Other metabolic challenges can also affect the horse, such as PPID or polycystic ovary syndrome. Genetic factors can also play a part in the horse’s health status.
Good blood vessel integrity is important in the horse, just as it is in humans. Systems that rely on healthy blood vessels include:
➡ The circulatory system: During exercise, the heart rate increases. It can increase from about 30 beats per minute at rest to over 200 beats per minute with strenuous exercise. Blood vessel integrity is important for that drastic change.
➡ Respiratory system: At rest, it’s estimated that 7-10 gallons of blood gets pumped through the lungs per minute. During exercise, this can increase to about 80 gallons per minute. Rupture of blood vessels during exercise can occur.
There are other systems as well, but these are two of the most prominent ones.
Rutin is a common herb that is used to support breathing in the horse. The core of rutin is quercetin with an attached disaccharide.
◆︎ Muscle support:
Quercetin also supports healthy muscle functioning. Key to muscle support is maintaining mitochondrial integrity. The mitochondria are the powerhouses of the cell.
As horse’s age, the horse’s muscles, especially the mitochondria, can be damaged by inflammatory cytokines. These inflammatory cytokines are created in response to:
» Environmental challenges: Heavy metals from the environment can enter the body. Because they are so dangerous, they are frequently sequestered within body tissues. Muscles are prime locations for this sequestration.
» Excessive body weight: Adipose cells within the body secrete inflammatory cytokines. These can negatively affect muscle tissue.
» Decreased growth factors: When there is a decrease in growth factors, new muscle fibers and mitochondria cease to be created. As the older muscle cells become damaged, they may atrophy and die. This can cause the number of muscle fibers and cells to diminish.
» Muscle wasting due to disease: This is evident in some horses with untreated or undertreated PPID. Despite having plenty of feed, the horse loses topline and body condition. This can be due to the body’s response to a pathogen, or an aberrant metabolic state.
» Atrophy from aging is a concern. This can be exacerbated by lack of exercise. It can be further damaging when the muscle cells are replaced with fat.
◆︎ Joint support:
Arthritis affects many horses. Quercetin may be able to support a horse with arthritis. Arthritis can be caused by degradation of the extracellular matrix, inflammation, decreased growth factors, or compromised mitochondrial integrity.
◆︎ Allergies:
☛ Allergies can be expressed as a breathing issue, or as a skin issue. It’s caused by an allergen interacting with the horse’s immune system. One of quercetin’s mechanisms of action is to inhibit inflammatory cytokines, histamine, and leukotrienes. It also stabilizes mast cells to inhibit degranulation. Because it can inhibit histamine release, it can be supportive in instances where an anti-itch remedy is needed.
☛ Quercetin may also be supportive in areas that have high levels of PM 2.5 particles. These are air pollutant particles that are less than 2.5 microns. They are particularly dangerous, as they are not filtered out by the lung cilia. They enter deep into the lungs and can be absorbed into the bloodstream. Quercetin has been shown to mitigate the negative effects of PM 2.5 particles.
◆︎ Liver support:
Quercetin can support a healthy liver. It has the ability to bind with heavy metals. Heavy metals are present in the environment, especially in industrialized areas. It may also be supportive for horses on SGLT2 inhibitors (-flozin drugs) that are used to lower insulin levels.
◆︎ Mitigate fibrosis within body:
The body’s response to inflammation and damage is the creation of fibrotic tissue. Quercetin also has been shown to reduce liver fibrosis by inhibiting hepatic stellate cells. Its antifibrotic mechanism of action is primarily due to the inhibition of fibrosis. It has a small positive effect on fibrotic tissue that already exists.
In the lung, it can inhibit the fibrosis due to chronic inflammation.
◆︎ Take home message:
Quercetin is a versatile supplement that can support horses that are affected by environmental, hormonal, and aging challenges. Because it has so many different mechanisms of action, it can be supportive in many different scenarios.
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Disclaimer: Statements regarding dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease or health condition.
©Joan Kulifay, MSc. 2025