What foods are high in Quercetin?Red Onion - Quercetin

Quercetin is a plant-derived flavonoid. Sources include fruits, vegetables, leaves and grains. The name has been used since 1857, and is derived from quercetum (oak forest).

In red onions higher concentrations of quercetin occur in the outermost rings and in the part closest to the root.  One study found that organically grown tomatoes had 79% more quercetin than conventionally grown  fruit.

Health Benefits

As a natural antihistamine it is being use as a supplement. Quercetin has shown nervous system and immune support as well as weight managing properties.

Quercetin is highly concentrated in apples (50 mg in one apple), onions, berries, tea, grapes, citrus fruit, tomatos, broccoli, leafy greens, and many other fruits and vegetables as well as red wine.

Paraoxonase-1 (PON-1) is the secret to clean arteries. This enzyme plays an important role in protecting arteries from plaque build-up by augmenting the removal of cholesterol from the walls of arteries. PON-1 also protects against lipid oxidation.  PON-1 helps to stabilize plaques by inhibiting chronic inflammation and platelet activation.

As humans age, PON-1 levels noticeably decline, thus reducing the ability of HDL to guard against heart attack and stroke.

The age-related reduction in PON-1 may also clarify studies presenting that statin drugs lose their value in some aging populations, since the effects of statins are no longer able to protect against the multiple factors involved in the advancement of atherosclerosis in the elderly.

Resveratrol is the best-known of the red wine polyphenols. It applies powerful control over the PON-1 gene, growing PON-1 expression in human liver cells and shielding against atherosclerosis in animal models.

Quercetin is an alternative polyphenol. It up-regulates PON-1 gene expression, defending against fat and cholesterol oxidation.

Quercetin holds unique antioxidant action. A study in October 2009 confirmed how Quercetin activates the key step leading to the making of cellular glutathione (a cell’s primary antioxidant). This mechanism sheltered the insulin producing beta cells of the pancreas, donating to healthier blood sugar function.

A 2009 study established that Quercetin protects against liver injury by antioxidant role. A January 2009 study showed that Quercetin presented noteworthy antioxidant protection for cells lining the sinuses. And a March 2009 study showed that Quercetin offers substantial antioxidant defense to the mitochondria (cell engines).


In a 2007 study that assessed the anti-Hepatitis B effects of Hyperoside, and that was published in the Acta Pharmacologica Sinica, it was shown that Hyperoside (which is the 3-O-galactoside of quercetin) is a strong inhibitor of HBsAg and HBeAg secretion in 2.2.15 cells.

In another study also published in 2007 in the Archives of Pharmacal Research it was shown that quercetin, quercitrin and myricetin 3-O-beta-D-galactopyranoside displayed inhibition against HIV-1 reverse transcriptase, all with IC50 values of 60 microM.

Quercetin has anti-tumor potential in laboratory studies, and has probable use in many cancers including pancreatic cancer, however human studies are difficult to find.

The American Cancer Society says while quercetin “has been promoted as being effective against a wide variety of diseases, including cancer,” and “some early lab results appear promising, as of yet there is no reliable clinical evidence that quercetin can prevent or treat cancer in humans.” In the amounts consumed in a healthy diet, quercetin “is unlikely to cause any major problems or benefits.”

Inflammation and aging
Inflammation in the blood vessels in addition with other factors increases the likelihood of plaque formation leading to cardiovascular disease. A study in 2007 showed that Quercetin can inhibit cytokines (inflammatory substances) from being formed. Quercetin blocks a cell mediator called NF-kappaB, which is connected to cancer and inflammation. Other studies have found additional anti-inflammatory properties on C-reactive protein, known as a indicator for possible cardiovascular disease.

Several laboratory studies show quercetin may have anti-inflammatory properties for a wide range of potential health benefits.

Quercetin has been reported to be of use in alleviating symptoms of hay fever (pollinosis). It was found to alleviate ocular but not the nasal symptoms of hay fever. Studies done in test tubes have shown quercetin may prevent immune cells from releasing histamines which might influence symptoms of allergies.

A study with rats showed that quercetin effectively reduced immediate-release niacin (vitamin B3) flush, in part by means of reducing prostaglandin D2 production.  A pilot clinical study of four humans gave preliminary data supporting this.

Well established are Quercetin’s antihistamine properties.  It has been found to steady mast cells in a way that helps reduce stress induced anxiety and allergic reactions.
Quercetin has shown that it can reduce the effects of stress in nerves while stopping reduction of nerve antioxidants due to stress. The neuro-protective properties of quercetin can be used in the treatment and management of stress and related disorders.


Quercetin Side Effects
Quercetin has been safely used in amounts up to 500 mg twice daily for 12 weeks. Safety of Long-term use or larger amounts It is not known.

When given intravenously (by IV) in appropriate amounts (less than 722 mg), quercetin is possibly safe. Larger amounts given by IV are possibly safe. There have been reports of kidney damage at higher doses.


So apparently Quarcetin is quite the bad-ass! To know that you can get quite a lot of it in you simply by eating apples is super fantastic!
Please check out the references below to learn more.







1) Quercetin Boosts Cellular Antioxidant Function, Protects Beta Cells  J Cell Biochem.  Kang JH, Chang SY, Jang HJ, Cho JM, Kim DB, Lee SS, Ko SH, Park YM, Needs PW, Jo YH, Kim MJ.

2) Antioxidant Properties of Quercetin Protect Against Liver Damage  Free Radic Res.   Yokoyama A, Sakakibara H, Crozier A, Kawai Y, Matsui A, Terao J, Kumazawa S, Shimoi K.

3) Quercetin and Q10 Protect Human Sinus Cells  Anticancer Res.  Reiter M, Rupp K, Baumeister P, Zieger S, Harréus U.

4) Quercetin Protects Mitochondria  The Journal of Nutritional Biochemistry  Mara Fiorania, Andrea Guidarellib, Manuela Blasaa, Catia Azzolinia, Manila Candiraccia, Elena Piattia and Orazio Cantoni.

5) Role of Quercetin in Disease Prevention  Curr Opin Clin Nutr Metab Care  Bischoff SC.

6) Quercetin Demonstrates Cardio Protection  J Pharm Pharmacol.  Annapurna A, Reddy CS, Akondi RB, Rao SR.

7) Quercetin and Blood Pressure  American Journal of Clinical Nutrition  Wai Mun Loke, Jonathan M Hodgson, Julie M Proudfoot, Allan J McKinley, Ian B Puddey and Kevin D Croft

8) Quercetin Supports Male Health  Fundam Clin Pharmacol  Ertuğ PU, Olguner AA, Oğülener N, Singirik E.

9) Quercetin Helps Offset Occluded Carotid Arteries  Phytother Res+  Yao Y, Han DD, Zhang T, Yang Z.

10) Quercetin Helps Stop Bone Loss   Biol Pharm Bull.   Woo JT, Nakagawa H, Notoya M, Yonezawa T, Udagawa N, Lee IS, Ohnishi M, Hagiwara H, Nagai K.

11) Quercetin Lowers Inflammation in an Arthritis Model  J Med Food.   Choi EJ, Bae SC, Yu R, Youn J, Sung MK.

12) Quercetin, Chondroitin, and Glucosamine Help Osteoarthritis  Biosci Biotechnol Biochem.  Matsuno H, Nakamura H, Katayama K, Hayashi S, Kano S, Yudoh K, Kiso Y.

13) Quercetin Stabilizes Mast Cells   J Biol Regul Homeost Agents.  Shaik YB, Castellani ML, Perrella A, Conti F, Salini V, Tete S, Madhappan B, Vecchiet J, De Lutiis MA, Caraffa A, Cerulli G.

14) Stress Activates Immune Cells in Skin  Am J Pathol,   Joachim RA, Handjiski B, Blois SM, Hagen E, Paus R, Arck PC.

15) Stress Activates Mast Cells  Science  Donald Pfaff, et al.

16) Quercetin Protects Against Stress Journal of Medicinal Food. Anil Kumar, R. Goyal

17) Ibid.

18) Quercetin Is A Powerful Regulator of Mast Cells  Clin Exp Allergy.  Lee JH, Kim JW, Ko NY, Mun SH, Kim DK, Kim JD, Kim HS, Lee KR, Kim YK, Radinger M, Her E, Choi WS.

19) Quercetin Prevents Inflammatory Signal Release from Mast Cells  Br J Pharmacol.  Kandere-Grzybowska K, Kempuraj D, Cao J, Cetrulo CL, Theoharides TC.

20) Quercetin and Alzheimer’s  The Journal of Nutritional Biochemistry.  Mubeen Ahmad Ansariabc, Hafiz Mohammad Abdulab, Gururaj Joshiab, Wycliffe O. Opiiab, D. Allan Butterfieldabc.

21) Quercetin Supports Nerve Healing  Spinal Cord.  Schültke E, Kamencic H, Skihar VM, Griebel R, Juurlink B.

22) Quercetin and Prostate Cancer   Prostate.   Aalinkeel R, Bindukumar B, Reynolds JL, Sykes DE, Mahajan SD, Chadha KC, Schwartz SA.

23) Quercetin Inhibits Changes that Lead to Colon Cancer  Journal of Nutrition  Cynthia A. Warren, Kimberly J. Paulhill, Laurie A. Davidson, Joanne R. Lupton, Stella S. Taddeo, Mee Young Hong, Raymond J. Carroll, Robert S. Chapkin, and Nancy D. Turner. .

24) Quercetin and the Flu  American Journal of Physiology-Regulatory, Integrative and Comparative Physiology.  J. Mark Davis, E.A. Murphy, J.L. McClellan, M.D. Carmichael, and J.D. Gangemi.

25) Quercetin Reduces Hepatitis C Virus Production  Hepatology.  Gonzalez O, Fontanes V, Raychaudhuri S, Loo R, Loo J, Arumugaswami V, Sun R, Dasgupta A, French SW.

26) Quercetin Inhibits Influenza A  Eur J Pharm Sci  Choi HJ, Song JH, Park KS, Kwon DH.

27) Quercetin Boosts Respiratory Antioxidants Upon Flu Exposure  Exp Lung Res.   Kumar P, Khanna M, Srivastava V, Tyagi YK, Raj HG, Ravi K.

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