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Quercetin
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'''Quercetin''' is one of many [[flavonoid]]s found in plant pigments, being orange to orange-yellow in color. It is the principal source flavonoid in human nutrition and is commonly used in food processing.<ref name="webmd" /> Quercetin is found in high concentrations in asparagus, red onions, broccoli and buckwheat. Other names for quercetin include: Citrus bioflavonoid, Sophoretin; Meletin; Quercetine; Xanthaurine; Quercetol; Quercitin; Quertine; Flavin.<ref name="pubchem">{{Cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/5280343| title = Quercetin | last = PubChem|website=pubchem.ncbi.nlm.nih.gov|language=en|access-date=2020-05-05}}</ref><ref name="drugscom">{{Cite web|url=https://www.drugs.com/npp/quercetin.html| title = Quercetin Uses, Benefits & Dosage - Drugs.com Herbal Database|website=Drugs.com|language=en|access-date=2020-05-05}}</ref> ==Function== Quercetin affects immunity and inflammation by acting mainly on [[leukocyte]]s and targeting many intracellular signaling kinases and phosphatases, [[enzyme]]s and membrane proteins often crucial for cellular specific function.<ref name="Chirumbolo2010">{{Citation| issn = 2212-4055| volume = 9 | issue = 4| pages = 263β285| last = Chirumbolo | first = Salvatore| title = The role of quercetin, flavonols and flavones in modulating inflammatory cell function| journal = Inflammation & Allergy Drug Targets| date = September 2010 | pmid = 20887269}}</ref> <ref name="Balavoine1999">{{Citation| doi = 10.1006/niox.1999.0206| issn = 1089-8603| volume = 3 | issue = 1| pages = 40β54| last1 = Balavoine | first1 = G.G. | last2 = Geletii | first2 = Y.V. | title = Peroxynitrite scavenging by different antioxidants. Part I: convenient assay| journal = Nitric Oxide: Biology and Chemistry| date = 1999 | pmid = 10355895}}</ref> == Food sources == Quercetin can be found in many foods including red onions, red wine, onions, [[green tea]], apples, asparagus, berries, broccoli and Brassica vegetables, [[kale]], [[ginkgo biloba]], [[St. Johnβs Wort|St. John's Wort]], American elder, and buckwheat tea.<ref name="webmd" /><ref name="pcrm">{{Cite web|url=https://www.pcrm.org/good-nutrition/food-and-mood| title = Food and Mood: Eating Plants to Fight the Blues | website = Physicians Committee for Responsible Medicine|language=en|access-date=2021-03-26}}</ref> ==Health uses== Quercetin supplements are often promoted for * prevention and treatment of certain types of cancer<ref name="safety">https://www.researchgate.net/profile/Karen-Hirsch-Ernst/publication/321014123_Safety_Aspects_of_the_Use_of_Quercetin_as_a_Dietary_Supplement/links/5c03d507a6fdcc1b8d502a93/Safety-Aspects-of-the-Use-of-Quercetin-as-a-Dietary-Supplement.pdf</ref> * atherosclerosis * high cholesterol * heart disease and [[:Category:Cardiac signs and symptoms|circulatory problems]] * [[diabetes]] * [[hay fever]] * cataracts * peptic ulcer * [[depression]] * schizophrenia * inflammatory conditions (asthma, gout) * [[chronic fatigue syndrome]] * chronic prostate<ref name="safety" /><ref name="webmd" /> However, many of these uses have weak evidence supporting them, and for some uses there is evidence that quercetin supplementation do not improve symptoms.<ref name="webmd" /> Quercetin is also taken by athletes to increase endurance and improve performance.<ref name="webmd">{{Cite web|url=http://www.webmd.com/vitamins-supplements/ingredientmono-294-quercetin.aspx?activeingredientid=294&| title = Quercetin: Uses, Side Effects, Interactions, Dosage, and Warning|website=webmd.com|language=en|access-date=2020-05-05}}</ref> Quercetin is a potent antioxidant.<ref name="Balavoine1999" /> Most of the information on [[flavonoid]]s concerns quercetin because with only sight changes to the backbone of flavones and subtle cell behavior mechanisms and responsiveness, flavoinoids can be modulating, biphasic and exert regulatory action on immunity and inflammation. Only a few flavones and flavonols have been assayed mainly due to chemical similarity to quercetin.<ref name="Chirumbolo2010" /> ==Safety== The US FDA has issued warning letters to manufacturers of supplements containing quercetin to withdraw health benefit claims and emphasize that quercetin is not a defined nutrient nor an [[antioxidant]], cannot be assigned a dietary content level and is not regulated as a drug to treat any human disease.<ref>[https://www.accessdata.fda.gov/scripts/warningletters/wlSearchResult.cfm?webSearch=true&qryStr=quercetin&Search=Search FDA's Electronic Reading Room - Warning Letters]</ref> The European Food Safety Authority evaluated possible health claims associated with consumption of quercetin, and found that no cause-and-effect relationship established for any physiological effect in human health or diseases.<ref>European Food Safety Agency (EFSA) NDA Panel (Dietetic Products, Nutrition and Allergies) (8 April 2011).</ref> ==Chronic fatigue syndrome== Quercetin's antioxidant and anti-inflammatory properties are thought to be important in resolving the pathophysiology of ME/CFS. Additionally, a 2009 study by J. Mark Davis, et al. (2008)<ref name="Davis2008">{{Citation| doi = 10.1152/ajpregu.90925.2008| issn = 0363-6119| volume = 296 | issue = 4| pages = 1071-R1077| last1 = Davis | first1 = J. Mark | last2 = Murphy | first2 = E. Angela | last3 = Carmichael | first3 = Martin D. | last4 = Davis | first4 = Ben| title = Quercetin increases brain and muscle mitochondrial biogenesis and exercise tolerance| journal = American Journal of Physiology - Regulatory, Integrative and Comparative Physiology| access-date = 2016-11-09| date = 2009-04-01| url = http://ajpregu.physiology.org/content/296/4/R1071 | pmid = 19211721}}</ref> showed markers of mitochondrial biogenesis in mouse skeletal muscle and brain, and on endurance exercise tolerance after a week of quercetin in their food. Luteolin is another flavonoid antioxidant which is common place. Flavonoids are believed to be poorly absorbed due to bring rapidly metabolized and excreted. There remains no evidence that polyphenols (of which flavonoids are subset of) have any relevance on the body. Additionally, although antioxidants in the diet are required to be healthy, there is considerable debate on which antioxidants are health promoting, in what amounts and if they can prevent or help chronic diseases. == Depression == Quercetin acts to inhibit the enzyme monoamine oxidase (MAO), an enzyme that breaks down the mood-influencing [[Neurotransmitter|neurotransmitters]] [[serotonin]], [[dopamine]] and [[norepinephrine]],<ref name="pcrm" /> although clinical trials in humans are lacking. ==See also== *[[Flavonoid]] ==Learn more== *[https://pubchem.ncbi.nlm.nih.gov/compound/Quercetin Quercetin] - Pubchem *[https://www.drugs.com/npp/quercetin.html Quercetin] - drugs.com ==References== {{Reflist}} [[Category:Potential treatments]] [[Category:Flavonoids]] [[Category:Supplements]] [[Category:Mast cell stabilizers]] [[Category:Depression alternative treatments]] [[Category:Depression treatments]]
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