What is Quercetin?

Quercetin is a pigment found in vegetables and fruits. Because of its antioxidant property, it scavenges free-radicals—a harmful substance that damage the cell structures.

quercetin berries

What is quercetin?

Foods such as berries, teas, onions, red wine, and apples produce the pigment quercetin. But herbs such as St. John’s wort and ginkgo biloba has it as well.

Quercetin is a powerful chemical which hunts free radicals—a harmful substance that damage DNA. No wonder, manufacturers made a supplement nowadays. It has antioxidant, anti-inflammatory, and antihistamine properties.

What are the Properties of Quercetin?

Quercetin is associated with many powerful properties including the following:


The antioxidant content of quercetin is considered more powerful than beta carotene, vitamin E, and vitamin C. Because of its antioxidant property, it is believed to fight free radicals off. Free radicals are these harmful molecules in the body which increase your risk of getting sick. Some factors that contribute to getting more free radicals are greenhouse gases, chemical toxins, radiation, cigarette smoke, and pollution.


Inflammation is part of the body’s natural response to heal faster. However, chronic inflammation is the kind of inflammation that can make some conditions worse than good. But inflammation can be reduced through the help of quercetin. It is shown in one animal study, wherein acute and chronic inflammation is both prevented; aside from the anti-arthritis property it has been shown. But while these results are promising, remember that there is no sufficient human study made yet to fully support this claim.


All types of bacteria won’t work against the antibacterial property of quercetin. Thus, viruses such as a respiratory syncytial virus, Japanese encephalitis, herpes simplex virus, and adenovirus has no effect against it. Moreover, bacteria relating to urinal, respiration, skin, intestines, and stomach is poor compared to the antibacterial property of quercetin.

What are the Possible Health Benefits of Quercetin?

Because of the mentioned properties, quercetin is believed to improve colds, inflammation, cardiovascular disease, and allergies. However, there is no scientific evidence to back it up.

Nevertheless, some studies exist on how the compound interacts with the following conditions.


Histamine is an inflammatory chemical associated with the signs of allergies. These include itching and sneezing. Lab experiments reported that quercetin has the ability to prevent certain immune cells from releasing histamine. Thus, allergic reactions are prevented. But a 2002 report said that allergic rhinitis has not enough good studies to support quercetin effect against it.

Heart Disease

One factor that contributes to cardiovascular diseases is an unhealthy diet. But because quercetin is based on fruits and vegetables, it reduces the risk of such diseases because it contains flavonoids. In fact, high consumption of fruits and vegetables that contains quercetin promote a healthy heart.


Cell structure research shows that quercetin is helpful in slowing down the growing cancer cell. It was even indicated in animal-based research that supplements can protect against some types of cancer including colon cancer. However, there is no enough human-based study to conclude the effect quercetin against cancer. What the American Cancer Society suggests is including quercetin-based food in your diet is a good habit.

Chronic Pelvic Pain Syndrome

Quercetin supplements are associated with promoting chronic pelvic pain syndrome among men. This has been shown in a study which involved 30 men. These participants have the condition of prostatitis, which is a condition characterized by an inflamed prostate gland. Thus, after giving them the supplement for some time, they have shown improvements with their symptoms.

Neurological Diseases

Having an imbalance amount of free radicals in the body results in oxidative stress, which is associated with many neurological diseases including Parkinson’s and Alzheimer’s disease. But through quercetin antioxidant property, oxidative stress may reduce. There has been a study on rats where it shows that quercetin protects it from oxidative stress. Additionally, the rat’s nervous system has been protected against certain harmful metals.

High Blood Pressure

Elevated blood pressure among 41 adults have been shown to reduce after a daily supplication of 730 mg quercetin in 28 days, according to a study conducted in 2007. Contrary to that result, participants with prehypertension (a condition where blood pressure is slightly increased) have shown no different after taking quercetin.

What are the Possible Side Effects of the Supplements?

Consuming an appropriate amount of quercetin is not harmful. Too much consumption may lead to unwanted results. For instance, intravenous use has some negative side effects including, dyspnea, vomiting, nausea, sweating, flushing, and even pain at the injection site. Meanwhile, taking it orally in a very high dose may cause tingling in the legs and arms. Moreover, a headache may manifest. But worst, an inappropriately high dose can lead to kidney damage.

Quercetin supplements are not largely monitored that is why there is no scientific test for its safety. The content may be different from what is indicated on its label. Lastly, there is not yet established safety for children, pregnant women, breastfeeding mothers, and individuals who have certain conditions and taking medications.

What is the Appropriate Dosage?

With the supervision of your health care provider, you may take quercitin up to 500 mg two times a day for 3 months. Longer than that time period has taken no evidence yet if considered safe. Thus, taking it short term is the safest.

Taking the right dose has a variety of factor to consider including gender, age, and medical history. If you are fully decided to take this supplement, the best move is to consult your health care provider. He/she may provide the best advice as he/she knows your medical information.

Taking Quercetin

Perhaps the best way to have quercetin in your system is to take it from its natural sources such as apples, onions, teas, buckwheat, and many others. But if you choose a supplement to take it down, consuming a product with papain or bromelain may be the best to partner it with. Bromelain and papain are fruit extracts that make quercetin absorption rapid.

Remember that there is not enough proof to support the health benefits of quercetin. But if you do want to try its supplement, informing your health care provider might be the best move; especially if you are using the supplement as a form of self-treatment. Self-treatment may cause serious consequences.

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