Quercetin

Proprietary Source

Quercetin 95% Q-Di 95™ produced by Jiaherb

Chemical Name

3,3',4'5,7-Pentahydroxyflavone

Immune support

Quercetin is a plant pigment (flavonoid). It is found in many plants and foods, such as red wine, onions, green tea, apples, berries, Ginkgo biloba, St. John's wort, American elder, and others.

Buckwheat tea has a large amount of quercetin. People use quercetin as a medicine.Quercetin is most commonly taken by mouth to treat conditions of the heart and blood vessels and prevent cancer. It is also used for arthritis, bladder infections, and diabetes.

Quercetin demonstrates activity against retroviruses as well as Herpes simplex, polio, parainfluenza, and respiratory syncytial viruses. In cell cultures, quercetin reduced the infectivity of viruses and blocked viral replication, possibly by induction of interferon, binding of viral capsid proteins, and inhibition of DNA gyrase and proteases.

Other uses

  • Asthma. Early research shows that taking quercetin might improve asthma symptoms and reduce the use of rescue inhalers in people with asthma.
  • A blood disorder that reduces levels of protein in the blood called hemoglobin (beta-thalassemia). Some people with beta-thalassemia need blood transfusions. These transfusions can cause too much iron to build up in the body. Early research shows that taking quercetin might reduce iron levels in people with beta-thalassemia who need blood transfusions.
  • Heart disease. Some research suggests that eating foods rich in quercetin, such as tea, onions and apples, may reduce the risk of death due to heart disease in elderly men. However, taking a daily quercetin supplement does not seem to improve heart disease risk factors in people who are healthy.
  • Kidney damage caused by contrast dyes (contrast induced nephropathy). Early research shows that taking quercetin before and after receiving contrast dye doesn't prevent kidney damage caused by the dye.
  • Muscle damage caused by exercise. Taking quercetin doesn't seem to help to prevent muscle soreness due to cycling or running. But it might prevent muscle damage associated with certain types of weight training.
  • Airway infections caused by exercise. Early research shows that taking quercetin may reduce the chance for upper respiratory infections after heavy exercise.
  • High cholesterol. Short-term use of quercetin does not appear to lower "bad cholesterol" (low-density lipoprotein (LDL) cholesterol) or total cholesterol, or to raise "good cholesterol" (high-density lipoprotein (HDL) cholesterol). But most of the studies conducted have been small and included people without high cholesterol. It's unclear if quercetin would show benefit in only people with high cholesterol.
  • High blood pressure. Early research suggests that taking quercetin produces a small decrease in blood pressure in people with untreated, mild high blood pressure. It's unclear if this reduction in blood pressure is clinically meaningful.
  • Kidney transplant. Some research suggests that taking a product containing quercetin and curcumin, starting within 24 hours of kidney transplantation, improves early function of the transplanted kidney when taken in combination with anti-rejection drugs.
  • Lung cancer. Higher intake of quercetin as part of the diet has been linked with a lower risk of lung cancer in people who smoke.
  • A grouping of symptoms that increase the risk of diabetes, heart disease, and stroke (metabolic syndrome). Taking quercetin doesn't appear to improve blood sugar or insulin levels in people who are at risk for metabolic syndrome. This includes people with diabetes, obesity, polycystic ovary syndrome (PCOS), or high blood pressure. But quercetin might help lower blood sugar in people with risk factors for metabolic syndrome who are under 45 years of age, those who take quercetin for 8 or more weeks, or those taking at least 500 mg of quercetin per day. It's unclear if quercetin helps with blood sugar in people who have already been diagnosed with metabolic syndrome.
  • Swelling (inflammation) and sores inside the mouth (oral mucositis). Early research suggests that taking quercetin does not prevent mouth sores caused by cancer drugs.
  • Ovarian cancer. One population study found no link between quercetin intake from the diet and the chance of ovarian cancer.
  • Pancreatic cancer. Some research suggests that eating high amounts of quercetin in the diet might reduce the chance of developing pancreatic cancer, especially in men who smoke.
  • A hormonal disorder that causes enlarged ovaries with cysts (polycystic ovary syndrome or PCOS). Research shows that taking quercetin improves hormone levels in women with PCOS by a small amount. In some people it might also improve how sensitive the body is to insulin. But it's unclear if these changes lead to improvements in symptoms of PCOS such as irregular periods.
  • Swelling (inflammation) of the prostate due to infection. Taking quercetin by mouth seems to reduce pain and improve quality of life, but doesn't seem to help urination problems in men with ongoing prostate problems that aren't due to infection.
  • Rheumatoid arthritis (RA). Research shows that taking quercetin reduces pain and stiffness in women with RA. But it doesn't seem to reduce the number of swollen or tender joints.


How it works

Quercetin has antioxidant and anti-inflammatory effects which might help reduce inflammation, kill cancer cells, control blood sugar, and help prevent heart disease.

The anti-inflammatory effects of quercetin might be due to inhibition of the production and activity of leukotrienes and prostaglandins and inhibition of histamine release by basophils and mast cells. Studies in cell cultures and in animals indicate that quercetin inhibits the cyclooxygenase-2 (COX-2) enzyme and nuclear factor-kappa B, which controls expression of genes encoding pro-inflammatory cytokines. However, effects on cyclooxygenase (COX)-2 production may not occur in vivo. It has been suggested that quercetin might be useful for reducing inflammatory cytokine release and muscle damage associated with prolonged, intense exercise. Quercetin decreases levels of some inflammatory cytokines in patients with rheumatoid arthritis. However, in humans undergoing intense exercise, quercetin does not seem to have significant effects on muscle or plasma cytokine levels or leukocyte cytokine mRNA expression.

Safety

Pregnancy and breast-feeding: There isn't enough reliable information to know if quercetin is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.Kidney problems: Quercetin might make kidney problems worse. Don't use quercetin if you have kidney problems.

Interactions with medications

Antibiotics (Quinolone antibiotics)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Taking quercetin along with some antibiotics might decrease the effectiveness of some antibiotics. Some scientists think that quercetin might prevent some antibiotics from killing bacteria. But it's too soon to know if this is a big concern.Some of these antibiotics that might interact with quercetin include ciprofloxacin (Cipro), gemifloxacin (Factive), levofloxacin (Levaquin), moxifloxacin (Avelox), and others.

Cyclosporine (Neoral, Sandimmune)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Quercetin might decrease how quickly the body breaks down cyclosporine. Taking quercetin with cyclosporine might increase the effects and side effects of cyclosporine.

Diclofenac (Voltaren, others)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Quercetin might decrease how quickly the body breaks down diclofenac. Taking quercetin with diclofenac might increase the effects and side effects of diclofenac.

Losartan (Cozaar)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Quercetin might increase how much losartan is absorbed into the body and decrease how quickly the body breaks down losartan. Losartan is normally broken down into another chemical (active metabolite) that has stronger effects on blood pressure than losartan. By decreasing how quickly the body breaks down losartan, quercetin also seems to decrease levels of losartan's active metabolite. Taking quercetin with losartan might increase the effects and side effects of losartan while decreasing the effects of losartan's active metabolite.

Medications changed by the liver (Cytochrome P450 2C8 (CYP2C8) substrates)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.Some medications that are changed by the liver include paclitaxel (Taxol), rosiglitazone (Avandia), amiodarone (Cordarone), docetaxel (Taxotere), tretinoins, repaglinide (Prandin), verapamil (Calan, Isoptin, Verelan, etc.), and others.

Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.Some medications that are changed by the liver include celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), irbesartan (Avapro), losartan (Cozaar), phenytoin (Dilantin), piroxicam (Feldene), tamoxifen (Nolvadex), tolbutamide (Tolinase), torsemide (Demadex), and warfarin (Coumadin).

Medications changed by the liver (Cytochrome P450 2D6 (CYP2D6) substrates)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.Some drugs that are changed by the liver include amitriptyline (Elavil), codeine, flecainide (Tambocor), haloperidol (Haldol), imipramine (Tofranil), metoprolol (Lopressor, Toprol XL), ondansetron (Zofran), paroxetine (Paxil), risperidone (Risperdal), tramadol (Ultram), venlafaxine (Effexor), and others.

Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Some medications are changed and broken down by the liver. Quercetin might change how quickly the liver breaks down some medications. Taking quercetin along with some medications that are broken down by the liver can increase or decrease the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.Some drugs that are changed by the liver include calcium channel blockers (diltiazem, nicardipine, verapamil), chemotherapeutic agents (etoposide, paclitaxel, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), glucocorticoids, alfentanil (Alfenta), fentanyl (Sublimaze), losartan (Cozaar), fluoxetine (Prozac), midazolam (Versed), omeprazole (Prilosec), lansoprazole (Prevacid), ondansetron (Zofran), propranolol (Inderal), fexofenadine (Allegra), amitriptyline (Elavil), amiodarone (Cordarone), citalopram (Celexa), sertraline (Zoloft), and numerous others.

Medications for diabetes (Antidiabetes drugs)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Quercetin might lower blood sugar in people with diabetes. Diabetes medications are also used to lower blood sugar. Taking quercetin along with diabetes medications might cause blood sugar to go too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.

Medications for high blood pressure (Antihypertensive drugs)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Quercetin seems to decrease blood pressure. Taking quercetin along with medications for high blood pressure might cause your blood pressure to go too low.Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDIURIL), furosemide (Lasix), and many others.

Medications moved by pumps in cells (Organic anion-transporting polypeptide substrates)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Some medications are moved by pumps in cells. Quercetin might change how these pumps work and affect how much of some medications get cleared from the body. This could make these medications stay in the blood for longer, which could increase the effects and side effects of these medications.Some of these medications that are moved by pumps in cells include bosentan (Tracleer), celiprolol (Celicard, others), etoposide (VePesid), fexofenadine (Allegra), fluoroquinolone antibiotics, glyburide (Micronase, Diabeta), irinotecan (Camptosar), methotrexate, paclitaxel (Taxol), saquinavir (Fortovase, Invirase), rifampin, statins, talinolol, torsemide (Demadex), troglitazone, and valsartan (Diovan).

Medications moved by pumps in cells (P-glycoprotein substrates)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Quercetin might affect the way certain medications are processed by the body. Quercetin might make these medications easier for the body to use and make them last longer in the body.Some of the drugs that may be affected in these ways by quercetin include paclitaxel, diltiazem, cyclosporine, saquinavir, digoxin, cancer drugs (etoposide, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), protease inhibitors (amprenavir, indinavir, nelfinavir), H2 antagonists (cimetidine, ranitidine), verapamil, corticosteroids, erythromycin, fexofenadine (Allegra), loperamide (Imodium), quinidine, and others.

Midazolam (Versed)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Quercetin might increase how quickly the body breaks down midazolam. Taking quercetin with midazolam might reduce the effects of midazolam.

Pravastatin (Pravachol)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Some drugs are taken up by the liver to be broken down and cleared from the body. Quercetin might decrease how quickly pravastatin is taken up by the liver. This might increase how long pravastatin stays in the blood which could increase the effects and side effects of pravastatin.

Warfarin (Coumadin)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Quercetin might increase the effects that warfarin has on the body. Taking quercetin and warfarin together might increase the chance of side effects of warfarin such as bruising and bleeding.


Interactions with Herbs, Supplements, and Foods

Herbs and supplements that might lower blood pressure

Quercetin can slightly lower blood pressure in people with high blood pressure. Taking quercetin along with other herbs and supplements that lower blood pressure might cause your blood pressure to go too low.Other herbs and supplements that can lower blood pressure include andrographis, casein peptides, cat's claw, coenzyme Q-10, fish oil, L-arginine, lyceum, stinging nettle, theanine, and others.

Herbs and supplements that might lower blood sugar

Quercetin might lower blood sugar in people with diabetes. Taking quercetin along with other herbs and supplements that can lower blood sugar might cause your blood sugar to go too low.Other herbs and supplements that might lower blood sugar include agaricus mushroom, devil's claw, fenugreek, guar gum, Panax ginseng, Siberian ginseng, and others.


Interactions with Foods

There are no known interactions with foods.

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