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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] Quercetin is found in high concentrations in carob, dill, red onions, buckwheat and kale.[2]

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

Health Uses[edit | edit source]

Quercetin supplements are used for prevention and treatment of cancer.[4] It is promoted for atherosclerosis, high cholesterol, heart disease and circulatory problems, too. People with diabetes, hay fever, cataracts, peptic ulcer, schizophrenia, inflammatory conditions (asthma, gout), chronic fatigue syndrome and chronic prostate infection use it. Quercetin is also taken by athletes to increase endurance and improve performance.[5]

Quercetin is a potent anti-oxidant.[6] 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.[3]

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.[7] 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.[8]

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.,[9] 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]

Further reading[edit | edit source]

References[edit | edit source]

  1. PVP - Quercetin dihydrate
  2. 2.02.1 Wikipedia - Quercetin
  3. 3.03.1 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 
  4. Quercetin dihydrate safety sheet on http://www.pvp.com.br (English)
  5. WebMD - Vitamins and Supplements - Quercetin
  6. 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 
  7. FDA's Electronic Reading Room - Warning Letters
  8. European Food Safety Agency (EFSA) NDA Panel (Dietetic Products, Nutrition and Allergies) (8 April 2011).
  9. 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.

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 controversial term, invented by the U.S. Centers for Disease Control, that generally refers to a collection of symptoms as “fatigue”. There have been multiple attempts to come up with a set of diagnostic criteria to define this term, but few of those diagnostic criteria are currently in use. Previous attempts to define this term include the Fukuda criteria and the Oxford criteria. Some view the term as a useful diagnostic category for people with long-term fatigue of unexplained origin. Others view the term as a derogatory term borne out of animus towards patients. Some view the term as a synonym of myalgic encephalomyelitis, while others view myalgic encephalomyelitis as a distinct disease.

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.