1. Lowers Inflammation
Flavonoids, (aka bioflavonoids or bioflavonoide) including quercetin, are important anti-inflammatories because they act as antioxidants, which mean they literally fight the natural process of oxidation that takes place over time as we age.
Quercetin can help stop damaging particles in the body known as free radicals, which negatively impact how cells work including damaging cell membranes, changing the way DNA works, increasing cell mutations and causing healthy cells to die. It can also reduce expression of inflammatory genes such as interleukin.
Research now shows us that inflammation is the root of most diseases, including heart disease, cancer, cognitive decline, some mental disorders and autoimmune disorders.
At this time, practitioners and patients report using quercetin to effectively fight conditions related to inflammation, including:
hardening of the arteries (atherosclerosis)
heart disease and circulation problems
insulin resistance and diabetes
eye-related disorders, including cataracts
allergies, asthma and hay fever
inflammation of the prostate, bladder and ovaries
chronic fatigue syndrome
chronic infections of the prostate
skin disorders, including dermatitis and hives
2. Fights Allergies
Is quercetin an antihistamine? Some consider it to be a natural antihistamine and an anti-inflammatory, possibly making it effective for lowering the effects of seasonal and food allergies, plus asthma and skin reactions.
However, most research to date has been conducted on animals and not humans.
Histamines are chemicals that are released when the immune system detects an allergy or sensitivity, and they are what account for uncomfortable symptoms we face whenever the body has an allergic reaction.
Quercetin can help stabilize the release of histamines from certain immune cells, which results in decreased symptoms like coughs, watery eyes, runny noses, hives, swollen lips or tongue, and indigestion.
Its long been used in ancient Chinese herbal formulas created to block allergies to certain foods (such as peanuts). Studies conducted on mice suggest that it may be equivalent at fighting allergies as some prescription medications, all with little to no side effects.
3. Supports Heart Health
Because of its ability to lower inflammation and oxidative stress, quercetin seems to be beneficial for people with heart and blood vessel-related disorders, according to a number of studies.
For example, eating lots of deeply colored fruits and veggies that contain flavonoids is linked to a lower risk of cardiovascular disease, and even death, in older adults, among reduced risk for vascular diseases.
Its also been connected to reduced risk for type 2 diabetes and obesity, which have many of the same risk factors as heart disease.
Studies done in animal and some human populations show that various types of flavonoids (quercetin, resveratrol and catechins, for example) can help reduce the risk of atherosclerosis, which is a dangerous condition caused by plaque building up within the arteries. Cut-off blood flow in the arteries is one of the primary risk factors for experiencing a heart attack or stroke, which is why cardiac arrest is less likely among people who eat a nutrient-packed diet.
Antioxidants also seem to protect the body from experiencing increases in LDL bad cholesterol and can help regulate blood pressure levels. Certain studies show that quercetin prevents damage to LDL cholesterol particles, and it seems that people who eat the most flavonoid-rich foods typically have healthier and lower cholesterol levels, plus fewer incidences of hypertension and high blood pressure.
In fact, if youve ever heard that red wine is good for your heart, thats because its a natural source of quercetin. Its one of the main active ingredients in red wine extract, which is associated with healthier heart function.
4. Helps Fight Pain
Taking quercetin supplements may help lower pain associated with autoimmune conditions such as arthritis, as well as infections, including those of the prostate and respiratory tract.
Thats because studies suggest quercetin reduces inflammatory pain. For example, theres some evidence from several small studies that people experiencing bladder pains from infections (causing an urgent need to urinate, swelling and burning) have fewer symptoms when taking quercetin supplements.
Flavonoids are also linked to reduced symptoms of prostatitis (inflammation of the prostate) and rheumatoid arthritis (RA). Theres evidence that when patients with RA switch from eating a typical Western diet to one higher in antioxidant-rich foods (like uncooked berries, fruits, vegetables, nuts, roots, seeds and sprouts), they experience less pain and reoccurring symptoms.
5. Might Help Improve Energy and Endurance
Quercetin is added to some athletic supplements because its believed to help increase athletic performance and endurance, likely because of its positive effects on blood flow.
Researchers from the School of Applied Physiology at the Georgia Institute of Technology found that, on average, quercetin provides a statistically significant benefit in human endurance exercise capacity (VO2 max) and endurance exercise performance).
While improvements were at times small, it makes sense that antioxidants could boost physical performance since they help increase the health of blood vessels, which carry oxygen and nutrients to muscle and joint tissue.
Other studies also show that it helps increase immune function and prevents susceptibility to illnesses that can occur when someone trains intensely and experiences exhaustion. One study found evidence that taking 500 milligrams of quercetin twice daily helped protect cyclers from developing exercise-induced respiratory infections following periods of heavy exercise.
Because it can boost your energy level, does quercetin affect sleep? For example, is there a link between quercetin and insomnia?
One study found evidence that it may alter the sleep-wake cycle partly through activation of GABA receptors. However, insomnia is generally not believed to be a common side effect of taking it in dietary supplement form.
6. Might Help Fight Cancer
A Boston University School of Medicine study published in the Journal of Biological Regulators and Homeostatic Agents shows a link between a nutrient-dense diet rich in quercetin plus other antioxidants and a lowered risk of cancer.
Quercetin seems to have potential chemo-preventive activity and might have a unique antiproliferative effect on cancerous cells, making it an effective addition to any natural cancer treatment approach. Research shows that this may result from the modulation of either EGFR or estrogen-receptor pathways.
Recent studies have found quercetin can help stop the processes involved in cell proliferation and mutation, the growth of tumors, and symptoms related to typical cancer treatments, such as radiation or chemotherapy.
At this time, the majority of studies done on quercetins effects on cellular functioning have involved animals, so more research is still needed to reveal specific effects on human cancer cells. This is especially true when taken in high doses above the amount someone would get from a healthy diet.
7. Helps Protect Skin Health
Capable of blocking mast cells, which are immune cells critical in triggering allergic reactions, inflammatory disease and autoimmune disease, research shows that quercetin helps protect skin from the effects of disorders like dermatitis and photosensitivity.
Flavonoids like quercetin block the release of many pro-inflammatory cytokines, such as IL-8 and TNF, which helps stop symptoms related to skin inflammation, even in people who dont find relief from other conventional treatments or prescriptions.
Studies have found that this compound has antioxidant and anti-inflammatory effects that help fight allergic and inflammatory diseases, as well as some prescriptions, when taken in oral supplement form. For example, some people take quercetin for eczema since it can inhibit the secretion of histamine and pro-inflammatory markers.
8. Protects Liver Health
Recent research has shown that this antioxidant has protective effects when administered to rats with ethanol-induced acute liver injury. Researchers concluded that quercetin, by multiple mechanisms interplay, demonstrates hepatoprotective effect on liver-injury induced by alcohol, by increasing ethanol metabolizing enzyme activities, increasing antioxidant system activities against oxidative stress, lowering the expressions of pro-inflammation cytokines.
A 2017 study found evidence indicating that quercetin attenuates liver inflammation and fibrosis in mice through inhibiting macrophages infiltration. Researchers believe it holds promise as potential therapeutic agent for human fibrotic liver disease, a condition triggered by liver injury and inflammation.
9. Protects Against Neurological Disorders
Theres mounting evidence showing that quercetin offers neuroprotective benefits, due to its ability to defend the brain against oxidative stress and inflammation, leading to potentially less risk for cognitive conditions like Alzheimers disease and dementia.
A 2018 study concluded that findings suggest a possible new protective role for dietary flavonoids on alzheimers disease (AD). The study found that administration of quercetin in early-middle stages of AD pathology ameliorates cognitive dysfunction and boosts protection mainly related to increased A² clearance and reduced astrogliosis, which is related to destruction of neurons.
Related: Berberine: The Plant Alkaloid that Helps Treat Diabetes & Digestive Problems
Chris Martenson has a PhD in Toxicology. He recommends Quercetin and zinc. I take both.