Quercetin

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Quercetin is one of many flavonoids 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.[1][2] Quercetin is found in high concentrations in asparagus, red onions, broccoli and buckwheat.

Other names include: Citrus bioflavonoid, Sophoretin; Meletin; Quercetine; Xanthaurine; Quercetol; Quercitin; Quertine; Flavin.[3][2]

Function[edit | edit source]

Quercetin affects immunity and inflammation by acting mainly on leukocytes and targeting many intracellular signaling kinases and phosphatases, enzymes and membrane proteins often crucial for cellular specific function.[4]

Food sources[edit | edit source]

Quercetin can be found in many foods including red onions, red wine, onions, green tea, apples, asparagus, berries, broccoli and Brassica vegetables, ginkgo biloba, St. John's Wort, American elder, tea and buckwheat tea.[5]

Health uses[edit | edit source]

Quercetin supplements are often promoted for

  • prevention and treatment of certain types of cancer[6]
  • atherosclerosis
  • high cholesterol
  • heart disease and circulatory problems
  • diabetes
  • hay fever
  • cataracts
  • peptic ulcer
  • schizophrenia
  • inflammatory conditions (asthma, gout)
  • chronic fatigue syndrome
  • chronic prostate[6][5]

However, many of these uses have weak evidence supporting them, and for some uses there is evidence that quercetin supplementation do not improve symptoms.[5]

Quercetin is also taken by athletes to increase endurance and improve performance.[5]

Quercetin is a potent anti-oxidant.[7] Most of the information on flavonoids 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.[4]

Safety[edit | edit source]

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.[8] 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.[9]

Chronic fatigue syndrome[edit | edit source]

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.,[10] showed markers of mitochondrial biogenesis in mouse skeletal muscle and brain, and on endurance exercise tolerance after a week of quercetin in their food.

See also[edit | edit source]

Learn more[edit | edit source]

References[edit | edit source]

  1. "PVP Sociedade Anônima | Quercetin Dihydrate". Retrieved May 5, 2020. 
  2. 2.02.1 "Quercetin Uses, Benefits & Dosage - Drugs.com Herbal Database". Drugs.com. Retrieved May 5, 2020. 
  3. PubChem. "Quercetin". pubchem.ncbi.nlm.nih.gov. Retrieved May 5, 2020. 
  4. 4.04.1 Chirumbolo, Salvatore (September 2010), "The role of quercetin, flavonols and flavones in modulating inflammatory cell function", Inflammation & Allergy Drug Targets, 9 (4): 263–285, ISSN 2212-4055, PMID 20887269 
  5. 5.05.15.25.3 "Quercetin: Uses, Side Effects, Interactions, Dosage, and Warning". www.webmd.com. Retrieved May 5, 2020. 
  6. 6.06.1 Quercetin dihydrate safety sheet on http://www.pvp.com.br (English)
  7. Balavoine, G. G.; Geletii, Y. V. (1999), "Peroxynitrite scavenging by different antioxidants. Part I: convenient assay", Nitric Oxide: Biology and Chemistry, 3 (1): 40–54, doi:10.1006/niox.1999.0206, ISSN 1089-8603, PMID 10355895 
  8. FDA's Electronic Reading Room - Warning Letters
  9. European Food Safety Agency (EFSA) NDA Panel (Dietetic Products, Nutrition and Allergies) (8 April 2011).
  10. Davis, J. Mark; Murphy, E. Angela; Carmichael, Martin D.; Davis, Ben (Apr 1, 2009), "Quercetin increases brain and muscle mitochondrial biogenesis and exercise tolerance", American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, 296 (4): –1071–R1077, doi:10.1152/ajpregu.90925.2008, ISSN 0363-6119, PMID 19211721, retrieved Nov 9, 2016 

enzyme - a substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.

membrane - The word "membrane" can have different meanings in different fields of biology. In cell biology, a membrane is a layer of molecules that surround its contents. Examples of cell-biology membranes include the "cell membrane" that surrounds a cell, the "mitochondrial membranes" that form the outer layers of mitochondria, and the "viral envelope" that surrounds enveloped viruses. In anatomy or tissue biology, a membrane is a barrier formed by a layer of cells. Examples of anatomical membranes include the pleural membranes that surrounds the lungs, the pericardium which surrounds the heart, and some of the layers within the blood-brain barrier.

chronic fatigue syndrome (CFS) - A fatigue-based illness. The term CFS was invented invented by the U.S. Centers for Disease Control as an replacement for myalgic encephalomyelitis (ME). Some view CFS as a neurological disease, others use the term for any unexplained long-term fatigue. Sometimes used as a the term as a synonym of myalgic encephalomyelitis, despite the different diagnostic criteria.

assay - 1. (verb) analysis (as of an ore or drug) to determine the presence, absence, or quantity of one or more components. 2. (noun) In biochemistry, any laboratory protocol used to test a sample for one or more qualities.

chronic fatigue syndrome (CFS) - A fatigue-based illness. The term CFS was invented invented by the U.S. Centers for Disease Control as an replacement for myalgic encephalomyelitis (ME). Some view CFS as a neurological disease, others use the term for any unexplained long-term fatigue. Sometimes used as a the term as a synonym of myalgic encephalomyelitis, despite the different diagnostic criteria.

ME/CFS - An acronym that combines myalgic encephalomyelitis with chronic fatigue syndrome. Sometimes they are combined because people have trouble distinguishing one from the other. Sometimes they are combined because people see them as synonyms of each other.

mitochondria - Important parts of the biological cell, with each mitochondrion encased within a mitochondrial membrane. Mitochondria are best known for their role in energy production, earning them the nickname "the powerhouse of the cell". Mitochondria also participate in the detection of threats and the response to these threats. One of the responses to threats orchestrated by mitochondria is apoptosis, a cell suicide program used by cells when the threat can not be eliminated.

assay - 1. (verb) analysis (as of an ore or drug) to determine the presence, absence, or quantity of one or more components. 2. (noun) In biochemistry, any laboratory protocol used to test a sample for one or more qualities.

The information provided at this site is not intended to diagnose or treat any illness.
From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history.