QUERCETIN

What is quercetin?

Quercetin is a flavonoid, a group of plant pigments that give fruits, vegetables, and flowers their colors. As a flavonoid, quercetin is a potent antioxidant. Along with the other members of the flavonoid family, quercetin reduces the risk of heart and metabolic disorders and certain cancers. Flavonoids work to combat oxidative stress in the body [^[1]].

What does quercetin do in the body?

Quercetin lowers coagulation and reduces hyperglycemia, inflammation, and hypertension. Quercetin supplementation is used to prevent and treat chronic diseases including, but not limited to, cardiovascular issues [^[2]].

How can quercetin help alleviate certain Long COVID symptoms and pathophysiology? 

As antioxidants, quercetin and other flavonoids prevent oxidative stress and buffer against the effects of aging [^[2]]. Quercetin is the most promising flavonoid to help deal with Long COVID because it has shown the ability to inhibit tumor necrosis factor alpha [^[3]]. Tumor necrosis factor alpha is one of the most important cytokines involved in the intense and severe chronic inflammation in Long COVID [^[4]].

While much remains to be known about Long COVID, an increasingly clear picture is emerging about its underlying mechanisms, and tumor necrosis factor alpha plays a role. Individuals with Long COVID have higher levels of tumor necrosis factor alpha and other types of immunoreactive cells than people who recovered fully from acute COVID infection [^[4]].

What else should I know about quercetin?

Quercetin supplementation via over-the-counter supplements is common, but significant drug interactions exist [^[5]]. According to WebMD, several drugs interact with quercetin, such as antibiotics, cyclosporin, warfarin, or drugs changed by the liver [^6]].