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Home > Anti-aging Research > Quercetin

Quercetin

Specific Recommendations:

• Quercetin products at iHerb

News & Research:

• Antioxidant may boost exercise endurance - msnbc.com, 6/29/09 - "Compared with days of no supplementation, the quercetin supplement periods were associated with a modest — nearly 4 percent — increase in maximum oxygen uptake. Quercetin was also associated with a 13 percent increase in "ride time" before the volunteers were too fatigued to continue"
• Quercetin Inhibits Path to Myocardial Ischemia-Reperfusion Injury - Medscape, 3/16/09 - "The naturally occurring flavone quercetin inhibits mRNA and protein expression of several components involved in the pathophysiology of myocardial ischemia-reperfusion injury in rabbits"
• Cranberry extracts may prevent colon cancer: Lab study - Nutra USA, 2/13/09 - "These findings are important because they demonstrate that the F-κB signalling pathway provides a potential mechanistic link between inflammation and cancer and that the anti-inflammatory properties of crude cranberry extract or quercetin can be used to modulate this pathway" - See Jarrow Formulas, Cran Clearance, 680 mg, 100 Capsules at iHerb.
• Flavonoids’ heart health benefits in the blood vessels: Study - Nutra USA, 10/10/08 - "A daily dose of quercetin or (-)-epicatechin led to improvements in endothelial function, a key marker of cardiovascular health" - [Abstract]
• Substance Found In Fruits And Vegetables Reduces Likelihood Of The Flu - Science Daily, 0/3/08 - "Mice that exercised and took quercetin had nearly the same rate of illness as those that did not exercise. In other words, quercetin canceled out the negative effect of stressful exercise ... Although this study was done with mice, a recent human study found that people who took quercetin suffered fewer illnesses following three days of exhaustive exercise compared to those who did not"
• Veggies, Exercise May Cut Cancer Risk - WebMD, 4/15/08 - "People who ate quercetin-rich foods at least four times a week, on average, were 51% less likely to have lung cancer than those who ate none"
• Onion compound linked to lower blood pressure - Nutra USA, 10/23/07 - "receive a daily supplement of quercetin (730 mg, USANA Health Sciences) or placebo for 28 days ... the hypertensives receiving the quercitin supplement experienced reductions in systolic and diastolic BP of seven and five mmHg, respectively, compared to placebo"
• Chemical in Curry May Cut Colon Cancer - WebMD, 8/2/06 - "Each of the patients then received 480 milligrams of curcumin and 20 milligrams of quercetin three times a day for six months ... The results showed that treatment with the curry and onion compounds reduced the average number of polyps by 60%, and decreased their size by 50%" - See iHerb curcumin products and iHerb quercetin products.
• Apples May Ward Off Alzheimer's Disease - WebMD, 11/18/04 - "The results suggest that quercetin "contributes significantly" to the protection of brain cells from free radicals in conditions like Alzheimer's disease"
• Mediterranean diet 'extends life' - bbc.co.uk. 8/24/03 - "The[y] found that quercetin, which is abundant in olive oil, has a similar effect"
• Drinking Tea May Help Prevent Heart Attacks - Doctor's Guide, 5/9/02 - "Drinking more tea and increasing flavonoid intake may help primary prevention of ischaemic heart disease ... The intake of the dietary flavonoids quercetin, kaempferol and myricetin was significantly associated inversely with fatal myocardial infarction only in upper tertiles of intake"
• Quercetin Relieves Prostate Pain - Nutrition Science News, 7/01
• Quercetin Is Promising for Chronic Prostatitis - Nutrition Science News, 4/01 - "an encouraging 59 percent of the subjects improved"
• Canceling Cancer: New Cancer Prevention Strategies on the Horizon - WebMD, 3/26/01 - "Xing has shown that quercetin blocks androgen receptors when applied to cancer cells in the laboratory ... We are very excited by our finding that the new approach quercetin [can be used] in the fight against prostate cancer"
• Eating apples improves lung function - Doctor's Guide, 1/26/00 - "Apples are high in the antioxidant flavoid quercetin. This antioxidant is also found in onions, tea and red wine and it may be important in protecting the lungs from the harmful effects of atmospheric pollution and cigarette smoke"
• New Study Offers Hope for Chronic Prostatitis Treatment - Medscape, 1/00 - "More than 80% of chronic prostatitis patients who took a proprietary formulation of quercetin, a natural dietary supplement, significantly reduced pain and improved their quality of life, according to a new study published in the December issue of Urology"

Abstracts:

• Quercetin Potentiates Apoptosis by Inhibiting Nuclear Factor-kappaB Signaling in H460 Lung Cancer Cells - Biol Pharm Bull. 2013;36(6):944-951 - "The herbal flavonoid quercetin inhibits the growth of various cancer cells, but how it affects human cancer cells, particularly lung cancer cells, is unclear ... Taken together, these findings suggest that quercetin may be useful in the prevention and therapy of NSCLC" - See quercetin products at iHerb.
• Resveratrol and Quercetin in Combination Have Anticancer Activity in Colon Cancer Cells and Repress Oncogenic microRNA-27a - Nutr Cancer. 2013 Apr;65(3):494-504 - "Resveratrol and quercetin (RQ) in combination (1:1 ratio) previously inhibited growth in human leukemia cells. This study investigated the anticancer activity of the same mixture in HT-29 colon cancer cells. RQ decreased the generation of reactive oxygen species (ROS) by up to 2.25-fold and increased the antioxidant capacity by up to 3-fold in HT-29 cells (3.8-60 μg/mL), whereas IC50 values for viability were 18.13, 18.73, and 11.85 μg/mL, respectively. RQ also induced caspase-3-cleavage (2-fold) and increased PARP cleavage. Specificity protein (Sp) transcription factors are overexpressed in colon and other cancers and regulate genes required for cell proliferation survival and angiogenesis" - See resveratrol products at iHerb and quercetin products at iHerb.
• Quercetin Induces Apoptosis via Mitochondrial Pathway in KB and KBv200 cells - J Agric Food Chem. 2013 Feb 14 - "In this study, anticancer activities of six compounds of flavonoids were investigated in human epidermoid carcinoma KB and KBv200 cells. Among these compounds, quercetin and acacetin showed strong inhibition of cell growth in KB and KBv200 cells"
• Dietary fat increases quercetin bioavailability in overweight adults - Mol Nutr Food Res. 2013 Jan 15 - "Epidemiologic evidence supports that dietary quercetin reduces cardiovascular disease (CVD) risk, but its oral bioavailability is paradoxically low. The aim of this study was to determine whether dietary fat would improve quercetin bioavailability in adults at high risk for CVD and to assess lipid-mediated micellarization of quercetin in vitro ... In a randomized, cross-over study, overweight/obese men and postmenopausal women (n = 4 M/5 F; 55.9 ± 2.1 years; 30.8 ± 1.4 kg/m(2) ) ingested 1095 mg of quercetin aglycone with a standardized breakfast that was fat-free (<0.5 g), low-fat (4.0 g), or high-fat (15.4 g) ... Compared to the fat-free trial, plasma quercetin maximum concentration (C(max) ), and area under curve (AUC(0-24 h) ) increased (p < 0.05) by 45 and 32%, respectively, during the high-fat trial"
• Protective Effects of Quercetin on Streptozotocin-induced Diabetic Nephropathy in Rats - Phytother Res. 2012 Dec 27 - "Diabetic nephropathy (DN) is an important microvascular complication and one of the main causes of end-stage renal disease. In this study, we examined the protective effects of quercetin on DN in streptozotocin-induced diabetic rats ... Compared with the levels in the DN group, quercetin decreased the levels of fasting blood glucose, creatinine, blood urea nitrogen, and urine protein, and the intensity of oxidative stress decreased significantly. Quercetin significantly inhibited the expression of advanced glycosylation end products, collagen IV, laminin, connective tissue growth factor, Smad 2/3, and transforming growth factor-β(1) mRNA. Moreover, quercetin was observed to inhibit proliferation of mesangial cells and decrease thickness of glomerular basement membrane. Those results suggest that quercetin has protective effects on several pharmacological targets in the progress of DN and is a potential drug for the prevention of early DN"
• Quercetin protects against pulmonary oxidant stress via heme oxygenase-1 induction in lung epithelial cells - Biochem Biophys Res Commun. 2011 Nov 25 - "In the present study, we showed that quercetin increased the levels of heme oxygenase (HO)-1 expression and protected against hydroxy peroxide (H(2)O(2))-induced cytotoxicity in lung epithelial cell lines. Quercetin suppressed H(2)O(2)-induced apoptotic events, including hypodiploid cells, activation of caspase 3 enzyme activity and lactate dehydrogenase release. This cytoprotective effect was attenuated by the addition of the HO inhibitor, tin protoporphyrin IX. In addition, the end products of heme metabolites catalyzed by HO-1, carbon monoxide and bilirubin, protect against H(2)O(2)-induced cytotoxicity in LA-4 cells. Quercetin may well be one of the promising substances to attenuate oxidative epithelial cell injury in lung inflammation"
• Anti-inflammatory, anti-proliferative and anti-atherosclerotic effects of quercetin in human in vitro and in vivo models - Atherosclerosis. 2011 May 5 - "In cultured human endothelial cells, quercetin protected against H(2)O(2)-induced lipid peroxidation and reduced the cytokine-induced cell-surface expression of VCAM-1 and E-selectin. Quercetin also reduced the transcriptional activity of NFκB in human hepatocytes. In human CRP transgenic mice (quercetin plasma concentration: 12.9±1.3μM), quercetin quenched IL1β-induced CRP expression, as did sodium salicylate. In ApoE*3Leiden mice, quercetin (plasma concentration: 19.3±8.3μM) significantly attenuated atherosclerosis by 40% (sodium salicylate by 86%). Quercetin did not affect atherogenic plasma lipids or lipoproteins but it significantly lowered the circulating inflammatory risk factors SAA and fibrinogen. Combined histological and microarray analysis of aortas revealed that quercetin affected vascular cell proliferation thereby reducing atherosclerotic lesion growth. Quercetin also reduced the gene expression of specific factors implicated in local vascular inflammation including IL-1R, Ccl8, IKK, and STAT3 ...Quercetin reduces the expression of human CRP and cardiovascular risk factors (SAA, fibrinogen) in mice in vivo. These systemic effects together with local anti-proliferative and anti-inflammatory effects in the aorta may contribute to the attenuation of atherosclerosis"
• Quercetin's Effects on Intestinal Polyp Multiplicity and Macrophage Number in the Apc(Min/+) Mouse - Nutr Cancer. 2011 Mar 1:1 - "Numerous in vitro studies argue for quercetin's chemopreventive potential in colon cancer; however, experimental studies in rodents are limited. Macrophages play a role in tumorigenesis, but the effects of quercetin on macrophage infiltration in colon cancer is unknown. We examined the effects of quercetin on intestinal polyp multiplicity and macrophage number in Apc(Min/+) mice ... These data suggest that quercetin can reduce polyp number and size distribution in the Apc(Min/+) mouse and that these effects may be related to a reduction in macrophage infiltration"
• The Flavonoid Quercetin Modulates the Hallmark Capabilities of Hamster Buccal Pouch Tumors - Nutr Cancer. 2011 Feb 2:1 - "Epidemiological studies have consistently demonstrated the protective effects of dietary phytochemicals against cancer risk. Quercetin, a ubiquitous dietary flavonoid, has attracted considerable attention owing to its potent antioxidant and antiproliferative activities ... Simultaneous administration of quercetin to DMBA-painted hamsters reduced tumor incidence and tumor burden, while posttreatment of quercetin resulted in a significant tumor growth delay. In addition, quercetin administration induced cell cycle arrest and apoptosis and blocked invasion and angiogenesis. We found a positive correlation between the inhibition of HDAC-1 and DNMT1 by quercetin and its anticancer properties. A dietary phytochemical such as quercetin that modulates a plethora of molecules offers promise as an ideal candidate for multitargeted cancer prevention and therapy"
• Quercetin is equally or more effective than resveratrol in attenuating tumor necrosis factor-{alpha}-mediated inflammation and insulin resistance in primary human adipocytes - Am J Clin Nutr. 2010 Oct 13 - "These data suggest that quercetin is equally or more effective than trans-RSV in attenuating TNF-α-mediated inflammation and insulin resistance in primary human adipocytes"
• Dietary flavonoid intake and colorectal cancer: a case-control study - Br J Nutr. 2009 Sep 7:1-8 - "We concluded that flavonols, specifically quercetin, obtained from non-tea components of the diet may be linked with reduced risk of developing colon cancer"
• Inhibition of UVA and UVB radiation-induced lipid oxidation by quercetin - J Agric Food Chem. 2009 Jun 24;57(12):5301-5 - "Quercetin, which absorbs UV radiation at 255 and 365 nm, was determined to be a stronger inhibitor of lipid oxidation induced by UVB (3.7 radicals scavenged per molecule) than by lipid oxidation induced by UVA (1.9 radicals scavenged per molecule). The values for inhibition of UVB-induced lipid oxidation by quercetin are comparable to those when 2,2'-azobis(2-amidinopropane) was used as an oxidizing system (four radicals scavenged per molecule). The protective effect of quercetin appears to be mainly the result of scavenging of UV-generated radical species, although this may be decreased slightly in the UVA as a result of its absorption at 365 nm"
• Quercetin inhibits fatty acid and triacylglycerol synthesis in rat-liver cells - Eur J Clin Invest. 2009 Jun 8 - "In hepatocytes from normal rats, the quercetin-induced decrease in both de novo fatty acid and TAG synthesis, with a consequent reduction in VLDL-TAG formation, may represent a potential mechanism contributing to the reported hypotriacylglycerolemic effect of quercetin"
• Quercetin reduces systolic blood pressure and plasma oxidised low-density lipoprotein concentrations in overweight subjects with a high-cardiovascular disease risk phenotype: a double-blinded, placebo-controlled cross-over study - Br J Nutr. 2009 Apr 30:1-10 - "Subjects were randomised to receive 150 mg quercetin/d in a double-blinded, placebo-controlled cross-over trial with 6-week treatment periods separated by a 5-week washout period. Mean fasting plasma quercetin concentrations increased from 71 to 269 nmol/l (P < 0.001) during quercetin treatment. In contrast to placebo, quercetin decreased systolic blood pressure (SBP) by 2.6 mmHg (P < 0.01) in the entire study group, by 2.9 mmHg (P < 0.01) in the subgroup of hypertensive subjects and by 3.7 mmHg (P < 0.001) in the subgroup of younger adults aged 25-50 years. Quercetin decreased serum HDL-cholesterol concentrations (P < 0.001), while total cholesterol, TAG and the LDL:HDL-cholesterol and TAG:HDL-cholesterol ratios were unaltered. Quercetin significantly decreased plasma concentrations of atherogenic oxidised LDL, but did not affect TNF-alpha and C-reactive protein when compared with placebo ... Blood parameters of liver and kidney function, haematology and serum electrolytes did not reveal any adverse effects of quercetin. In conclusion, quercetin reduced SBP and plasma oxidised LDL concentrations in overweight subjects with a high-CVD risk phenotype. Our findings provide further evidence that quercetin may provide protection against CVD"
• Quercetin up-regulates paraoxonase 1 gene expression with concomitant protection against LDL oxidation - Biochem Biophys Res Commun. 2009 Jan 10 - "Compared to the pair-fed control group, feeding quercetin (10mg/L) in the liquid diet for 4 weeks increased (a) hepatic expression of PON1 by 35% (p<0.01), (b) serum and liver PON1 activities by 29% (p<0.05) and 57% (p<0.01), respectively, and (c) serum homocysteine thiolactonase (HCTL) activity by 23% (p<0.05). Correspondingly, the lag time of low-density lipoprotein (LDL) oxidation was increased by >3-fold (p<0.001) with plasma HDL from quercetin-fed group compared to the HDL from control group. Our data suggest that quercetin has antiatherogenic effect by up regulating PON1 gene expression and its protective capacity against LDL oxidation"
• Protective Effect of Quercetin against Gentamicin-Induced Nephrotoxicity in Rats - Pharm Bull. 2009 Jan;32(1):61-7 - "Gentamicin (GM) is an antibiotic widely used in treating severe gram-negative infections. However, its clinical use is limited by its nephrotoxicity ... Histopathological examination of GM-treated rats revealed degenerative changes in glomeruli and tubules. On the other hand, simultaneous administration of quercetin plus gentamicin protected kidney tissues against nephrotoxic effects of gentamicin as evidenced from amelioration of histopathological changes and normalization of kidney biochemical parameters"
• Pure dietary flavonoids quercetin and (-)-epicatechin augment nitric oxide products and reduce endothelin-1 acutely in healthy men - Am J Clin Nutr. 2008 Oct;88(4):1018-25 - "Dietary flavonoids, such as quercetin and (-)-epicatechin, can augment nitric oxide status and reduce endothelin-1 concentrations and may thereby improve endothelial function"
• Serum C-reactive protein concentrations are inversely associated with dietary flavonoid intake in u.s. Adults - J Nutr. 2008 Apr;138(4):753-60 - "Among the flavonoid compounds investigated, quercetin, kaempferol, malvidin, peonidin, daidzein, and genistein had inverse associations with serum CRP concentration"
• Quercetin inhibits vascular superoxide production induced by endothelin-1: Role of NADPH oxidase, uncoupled eNOS and PKC - Atherosclerosis. 2008 Mar 16 - "Chronic administration of the most abundant dietary flavonoid quercetin exerts antihypertensive effects and improves endothelial function ... endothelin-1 (ET-1, 10nM). ET-1 increased the contractile response induced by phenylephrine and reduced the relaxant responses to acetylcholine in phenylephrine contracted intact aorta, and these effects were prevented by co-incubation with quercetin, isorhamnetin or chelerythrine (protein kinase C (PKC) inhibitor). This endothelial dysfunction was also improved by superoxide dismutase (SOD), apocynin (NADPH oxidase inhibitor) and sepiapterin (tetrahydrobiopterin synthesis substrate). Furthermore, ET-1 increased intracellular O(2)(-) production in all layers of the vessel, protein expression of NADPH oxidase subunit p47(phox) without affecting p22(phox) expression and lucigenin-enhanced chemiluminescence signal stimulated by calcium ionophore A23187. All these changes were prevented by both quercetin and isorhamnetin. Moreover, apocynin, endothelium denudation and N(G)-nitro-l-arginine methylester (l-NAME, nitric oxide synthase inhibitor) suppressed the ET-1-induced increase in A23187-stimulated O(2)(-) generation. Moreover, quercetin but not isorhamnetin, inhibited the increased PKC activity induced by ET-1"
• The flavonoid luteolin inhibits niacin-induced flush - Br J Pharmacol. 2008 Jan 28 - "Sustained release niacin effectively lowers serum cholesterol, LDL and triglycerides, while raising HDL. However, 75% of patients experience cutaneous warmth and itching known as flush, leading to discontinuation. Acetylsalicylic acid (aspirin) reduces this flush only by about 30% ... Quercetin and luteolin (4.3 mg per rat; 1000 mg per human), administered i.p. 45 min prior to niacin, inhibited the niacin effect by 96 and 88%, respectively. Aspirin (1.22 mg per rat; 325 mg per human) inhibited the niacin effect by only 30%. Niacin almost doubled plasma PGD(2) and 5-HT, but aspirin reduced only PGD(2) by 86%. In contrast, luteolin inhibited both plasma PGD(2) and 5-HT levels by 100 and 67%, respectively"
• Quercetin selectively inhibits bioreduction and enhances apoptosis in melanoma cells that overexpress tyrosinase - Nutr Cancer. 2007;59(2):258-68 - "quercetin can selectively sensitize Tyr+ expressing melanoma cells to apoptosis and may serve as an adjuvant to chemotherapy by enhancing cell death and interfering with GST-mediated drug resistance"
• Quercetin reduces blood pressure in hypertensive subjects - J Nutr. 2007 Nov;137(11):2405-11 - "730 mg quercetin/d for 28 d vs. placebo ... reductions in (P < 0.01) systolic (-7 +/- 2 mm Hg), diastolic (-5 +/- 2 mm Hg), and mean arterial pressures (-5 +/- 2 mm Hg) were observed in stage 1 hypertensive patients after quercetin treatment"
• Comparative effects of quercetin and its predominant human metabolites on adhesion molecule expression in activated human vascular endothelial cells - Atherosclerosis. 2007 Sep 17 - "both quercetin and its metabolites, at physiological concentrations, can inhibit the expression of key molecules involved in monocyte recruitment during the early stages of atherosclerosis"