The Ultimate Guide to Quercetin


What is quercetin?

Quercetin (117-39-5) belongs to a group of compounds called flavonoids. Its chemical name is 3, 3′,4′,5,7-pentahydroxyflavone. It is a pigment that exists naturally in many vegetables, fruits, and grains and is among the leading antioxidants in diets. Quercetin is also available in capsule form and also in powder form as a dietary supplement.

Quercetin (117-39-5) helps the body in combating the damages caused by free radicals that are linked to many chronic diseases. Its antioxidant properties also help in reducing blood pressure, allergy symptoms, and inflammation.


How does Quercetin work?

Quercetin has anti-inflammatory and antioxidant effects that help in reducing prostate inflammation. It’s able to inhibit the oxidation of other compounds or molecules because it contains a polyphenolic chemical that scavenges on free radicals.

It also inhibits or activates the activities of many proteins. For example, it inhibits the actions of protein kinase while at the same time activating estrogen receptors.

Some studies suggest quercetin may:

  • Reduce damage to fats by oxidation
  • Block the release of histamine, a nitrogenous compound which masts cell activation and affects allergies
  • Neutralize ROS and free radicals
  • Boost glutathione levels.  Glutathione prevents damage to cellular components caused by free radicals
  • Blocking inflammatory pathways and substances (including CRP and COX-2) hence reducing inflammation
  • Increase the overall antioxidant power of the blood
  • Be active against some viruses and bacteria


Quercetin use

For quercetin to be effective you must only use it when recommended by your doctor. Even if you’ve made a personal decision to use it, you need to get approval from your doctor. And before you begin taking the quercetin supplement, ensure you read the patient’s information on the leaflet that comes with the supplement. Follow the instructions carefully before quercetin use, and ensure you ask your healthcare provider or doctor any questions you might have in mind.

For quercetin to be effective, stick to the dose prescribed by your healthcare provider – do not increase or decrease the dosage or stop using the supplement without consulting your healthcare provider. Note that taking high quercetin dosage may put too much stress on your kidneys. Meaning you only need to take the prescribed dose to prevent unnecessary health concerns.

Quercetin is usually taken daily, and to benefit most from its effects, you are supposed to take it regularly.


The Ultimate Guide to Quercetin


Quercetin dosage

If you decide to take a quercetin supplement then the recommended daily dose is 500 mg. Some people can take up to 1000 mg daily to enjoy full quercetin benefits. The supplement may also include vitamin C, bromelain or any substances that help your body to effectively absorb quercetin.

The suitable quercetin dosage for an individual depends on factors including medical history, gender, and age. That’s why you need to speak to your doctor, healthcare provider, or pharmacist to get appropriate advice and dose if you choose to take quercetin.


Quercetin benefits

The antioxidant properties of quercetin have been linked to many health benefits. Some of these quercetin benefits include:


Quercetin for immune Defense

Quercetin use may have some positive effects on the immune system. In one study, 1000 people were put on a dose of 1000 mg of quercetin per day. The drug managed to significantly reduce their sick days and the severity of the symptoms of the common cold.

Athletes on endurance exercises are more likely to catch a common cold because they usually exhaust their bodies by frequent stretching. A dose of 1000 mg of quercetin per day was found to reduce the incidences of the common cold and incidences of respiratory infections in 40 trained athletes on endurance training.

Quercetin was given to them after 3 days of intense endurance exercise over the exercise recovery period which took two weeks.


The Ultimate Guide to Quercetin


Quercetin as an anti-aging agent

Researchers believe that quercetin is “senolytic” in that it can stop the process of aging. In one study done on human skin, quercetin was found to eliminate the harmful senescent cells which are responsible for aging.

In another study, quercetin was found to have the ability to increase stress resistance in worms and also to increase their lifespan. In yet another study, quercetin was found to increase the lifespan of worms by 15% while at the same time increasing their ability to handle stress. The results of these studies suggest that quercetin can be used as an anti-aging agent.


Asthma and Allergies

If you are allergic or suffering from asthma, quercetin can be an answer to your problem. Some people who have used it have reported that it helps with Th2 dominance. Quercetin can relax smooth muscles lining the airways thereby improving the airway flow.

Quercetin has also been found to reduce allergies due to foods such as soy, tree nuts, shellfish, wheat, fish, peanuts, eggs, lactose, and other foods that trigger allergic responses. In one animal study, it was found that quercetin can balance immune response and reduce allergies.

If you are suffering from mast cell activation syndrome, the overactive mast cell will release molecules such as cytokines, leukotrienes, histamine, and other harmful chemicals in your body. These chemicals cause inflammation similar to that which occurs during an allergic response.

Quercetin can block the activation of mast cells in your body hence preventing them from releasing the harmful chemicals that cause inflammation.

If you are suffering from hay fever, it means your histamine H1 receptor gene is over-expressed. When this gene is over-expressed, your allergy symptoms will be more severe. Quercetin has been found to reduce the expression on the H1R gene hence reducing the allergic symptoms.


Quercetin may reduce inflammation

Inflammation is caused by free radicals which damage boy cells. High levels of free radicals activate genes that trigger inflammation.

While your body needs a little inflammation to fight infections and heal, persistent or high levels of inflammation are known to cause health problems including kidney and heart diseases, as well as some cancers.

Some studies have shown that quercetin helps in reducing inflammation. In one test-tube study, it was found that quercetin was able to reduce inflammation markers in human cells such as the tumor necrosis molecules interleukin-6 (IL-6) and alpha (TNFα).

In another study involving 50 women who had been diagnosed with rheumatoid arthritis, the subjects took 500 mg of quercetin for eight weeks. After the eight weeks, the participants reported a significant reduction in after-activity pain, morning pain, and early morning stiffness.

The participants also experienced a remarkable reduction in inflammation markers than those in the control group.


Quercetin may ease allergy symptoms

The anti-inflammatory properties of quercetin may provide relief for allergy symptoms. Animal and test-tube studies have found that quercetin can block the enzymes responsible for inflammation and it also suppresses chemicals that promote inflammation.

For instance, in one study, mice that are allergic to peanuts were given quercetin supplements. The results of the study were quite promising as it showed that taking the supplements suppressed their anaphylactic reactions.


Quercetin may have anticancer effects

The cancer-fighting properties of quercetin can also be attributed to its antioxidant properties. In some animal and test-tube studies, it was found that quercetin induces the death of prostate cancer cells and suppresses the growth of the same cells.

In other studies, it was found that quercetin has similar effects in adrenal, lymphoid, ovarian, colon, blood, bladder, breast, lung, and liver cancer cells.


Quercetin may lower the risk of chronic brain disorders

From research findings, quercetin may help protect against dementia, Alzheimer’s disease and other degenerative brain disorders.

In one study that took three months, quercetin injections were administered to mice with Alzheimer’s disease. At the end of the three months, it was found that several Alzheimer’s markers had been reduced and the mice performed so well in learning tests.

Another study was conducted on mice with the early mid-late stage of the disease and the results were remarkable. The animals were fed on a diet rich in quercetin for the duration of the study. At the end of it, the animals showed improved brain functions and a reduction in Alzheimer’s disease markers.

For many years, coffee has been known to lower the risk of Alzheimer’s disease. Research has shown that this protective effect results from quercetin in coffee and not from the caffeine.


The Ultimate Guide to Quercetin


Quercetin may reduce blood pressure

Research has shown that high blood pressure is the leading cause of death in the U.S. In fact, the condition affects one out of three adults in America.

From one test-tube study, quercetin was found to have the ability to lower blood pressure levels. The compound was found to cause relaxation of the blood vessels.

In another research conducted on mice, it was found that their diastolic and systolic blood pressure levels (lower and upper numbers) were lowered by 23% and 18% respectively.

In a review of human studies involving 580 people, it was found that their diastolic and systolic blood pressure reduced by 2.6 mmHg and 5.8 mmHg respectively after taking more than 500 mg of quercetin supplement daily.


Quercetin may improve metabolic Health

Some research suggests that quercetin use can improve metabolic health. In one study 78 obese women, polycystic ovary syndrome took 1000 mg of quercetin per day for 12 weeks. The results showed that the levels of LH, testosterone, and resistin (obesity marker) were reduced in these women.


Quercetin helps in post-exercise recovery

Among the quercetin benefits are that it helps in enhancing recovery after training exercises. In one study 30 cyclists were put on quercetin of 1000 mg per day after very heavy training.

The chemical was found to improve their recovery, especially when combined with other anti-inflammatories and antioxidants such as DHA, EPA, isoquercetin, and EGCG.

In another study, quercetin reduced oxidative stress and post-exercise inflammation after 2 weeks in untrained young men.


Quercetin may treat ulcers

In one trial, 40 men took quercetin directly by mouth. In half of the cases, this drug helped to relieve their pain within 7 – 10 days. Their ulcers also got healed.

There is research currently going on to find out the effect of quercetin against acid reflux, Helicobacter pylori, and stomach ulcers.


Quercetin side effects

Quercetin is generally safe because it is obtained from fruits and vegetables. Even as a supplement, it appears to be very safe with no or little side effects. In some instances, when you take more than 1000 mg of the drug per day, you may experience some quercetin side effects such as:

  • Tingling and numbness
  • Headache
  • Shortness of breath
  • Kidney damage if administered intravenously in doses greater than 945 mg/m2
  • Vomiting and nausea

When taken with food, quercetin is also safe for breastfeeding and pregnant women. However, there are no scientific studies to support the safety of quercetin supplements for breastfeeding or pregnant women. So if you are pregnant or breastfeeding, you need to consult your doctor before consuming the drug to avoid any quercetin side effects.

As with all other supplements, if you are taking any other medications, it is advisable to consult your doctor before taking quercetin because it can interact with these other medications.


Quercetin’s interaction with other drugs

If your health care provider directs you to use quercetin, bring to his attention any other medications you are currently using. Your health care provider should be aware of any interactions that may happen between the medications you are using and quercetin and will be in a better position to monitor you for these interactions. Once you start using quercetin, do not change, stop, or start using any other medication before consulting your doctor, pharmacist, or health care provider.

Quercetin has severe interactions with topotecan and everolimus but has moderate interactions with more than 60 other drugs, among them:

  • armodafinil
  • alvimopan
  • ciprofloxacin
  • fleroxacin
  • fexofenadine
  • gemifloxacin
  • loratadine
  • levofloxacin
  • moxifloxacin
  • ofloxacin
  • norfloxacin

The list above is not comprehensive. So, before using quercetin, tell your pharmacist or doctor all the medications you are using. You need to keep a list of all your medications and share this information with your healthcare provider.

Some drugs are broken down or changed by the liver. When you take quercetin together with these drugs, it may lower the rate at which the liver breaks down or changes these drugs. This may increase the side effects of these other drugs. So, before you take quercetin alongside these drugs that are changed or broken down by the liver, you need to talk to your healthcare provider about it. Some of these drugs include:

  • Avandia  (rosiglitazone)
  • Taxol  (paclitaxel)
  • verapamil (Verelan, Isoptin,  Calan, etc.)
  • Cordarone (amiodarone)
  • tretinoins
  • Taxotere  (docetaxel)
  • Prandin (repaglinide), and others.

There are also other drugs such as P-glycoprotein Substrates that are moved by pumps in cells. When quercetin is used together with such drugs, it may increase the rate at which these drugs get absorbed by making the pumps to be less active. When that happens the side effects of these drugs will be more severe. These drugs include:

  • Cardizem (diltiazem)
  • Lanoxin (digoxin)
  • Verapamil (Ispotin, Calan, Verelan)
  • Cyclosporine (Sandimmune, Neoral)
  • Agenerase  (amprenavir)
  • Invirase (saquinavir)
  • Viracept  (nelfinavir)
  • Quinidine
  • Imodium (loperamide)
  • vincristine
  • Taxol  (paclitaxel)
  • Etoposide (VePesid, VP16)
  • Zantac (ranitidine)
  • Tagamet  (cimetidine)
  • Allegra  (fexofenadine)
  • Sporanox  (itraconazole)
  • Nizoral  (ketoconazole), and others.


Quercetin reviews

The name quercetin has been in use since 1857. As stated earlier, quercetin is a flavonoid and it is the most abundant of all. Plants containing flavonoids have been used in many cultures for their medicinal values. However, flavonoids were discovered in the 1930s and were identified as the compounds responsible for the many health benefits of the plants containing them.

Quercetin came into the limelight several years ago when scientists discovered that it can cause mutations in bacteria, a property that had the potential of causing cancer.

However, from all the quercetin reviews and studies, the supplement has been found to contribute to the suppression of cancer cells. Today, there are many quercetin reviews online and the best way to identify a good quercetin supplier is to read these reviews.


The Ultimate Guide to Quercetin


Quercetin powder for sale

Quercetin supplements come in different forms. Some come in capsule form while some come in powder form. The capsule form of quercetin is easy to swallow because it is slick. Quercetin powder for sale is also available in gummy forms which are great for kids. Liquid quercetin supplements are available in some outlets and they come in the form of sprays or drops.

When it comes to choosing quercetin supplements, it is good to consider which form works best for you. Many people report that quercetin supplements powder works better and is easy to use. The powder forms of quercetin can also be mixed into food or a beverage.

Quercetin powder for sale is packed in quantities that take into consideration the recommended quercetin dosage so you can buy the exact quantity you need. The dosage for quercetin powder (117-39-5) is usually two scoops per day. This will only be sufficient if you but from a trusted source. Low-quality quercetin powder may require you to consume more than two scoops per day.

Another thing you need to consider when buying quercetin powder is its strength or potency. A high-quality quercetin powder should contain between 500 – 1,200 mg per dose. Anything lower than that is not recommended and should not be purchased. For children, the recommended quercetin dosage is about 100 mg per day.

Quercetin powder for sale in reputable outlets usually contains some additional ingredients to enhance the anti-inflammatory and antioxidant properties of quercetin.


Where to buy Quercetin powder

There are many outlets where you can buy quercetin powder. These outlets also sell quercetin powder in bulk in case you want to re-sell.

Reports have shown that not all quercetin products contain what the labels claim they contain. After purchasing, reviewing, and testing a variety of quercetin products used in the U.S., a study found out that two products contained up to 14% less quercetin that what was listed on their labels.

That’s why before you buy quercetin powder, it’s good to do so only from trusted sources or a reputable quercetin supplier.

You can buy quercetin online, but before you do so, ensure you read their online reviews to learn what their previous customers have to say. If possible, let your friends or family members recommend a good quercetin supplier for you.

Are you looking for an online store with high-quality quercetin powder and with excellent customer service? You can order from us.


Final Words

Quercetin is a very popular flavonoid. The supplement has been linked to reduced blood sugar levels, blood pressure, inflammation, and enhanced exercise performance. Scientists also believe that quercetin has anticancer, anti-allergy, and brain-protective properties.

If you want to supplement your diet with quercetin, you should seek advice from a doctor or a healthcare provider first. Finally, ensure you buy quercetin powder only from reputable suppliers.



  • Quercetin, Inflammation and Immunity, Yao Li, Jiaying Yao, Chunyan Han, Jiaxin Yang, Maria Tabassum Chaudhry, Shengnan Wang, Hongnan Liu, and Yulong Yin2, NCBI.
  • Davis J.M., Murphy E.A., Carmichael M.D. Effects of the dietary flavonoid quercetin upon performance and health.  Sports Med. Rep. 2009;8:206–213.
  • Formica JV, Regelson W (1995). “Review of the biology of quercetin and related bioflavonoids”. Food and Chemical Toxicology. 33 (12): 1061–80.





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