Serving Size: 1 Capsule
Quercetin … 500 mg
Non-medicinal ingredients: potassium nitrate (providing 259 mg nitrates), green tea extract, citric acid. Capsule: hypromellose.
AOR Guarantees: that no ingredients not listed on the label have been added to the product. Contains no citrus, wheat, gluten, corn, nuts, dairy, soy, eggs, fish, shellfish or any animal byproduct.
Quercetin - Dimorphandra mollis seeds (citrus-free)
Adult Dosage: Take 1 capsule twice daily with food, or as directed by a qualified health care practitioner.
Cautions: Consult a health care practitioner before using this product if you are taking erectile dysfunction-type products or any other nitrate containing medications (or supplements) or for use beyond 1 month.
Pregnancy/Nursing: Do not take
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.
Loke WM, Hodgson JM, Proudfoot JM, McKinley AJ, Puddey IB, Croft KD.
BACKGROUND: Dietary flavonoids may improve endothelial function and ultimately lead to beneficial cardiovascular effects.
OBJECTIVE: The objective was to assess whether pure dietary flavonoids can modulate nitric oxide and endothelin-1 production and thereby improve endothelial function.
DESIGN: A randomized, placebo-controlled, crossover trial in 12 healthy men was conducted to compare the acute effects of the oral administration of 200 mg quercetin, (-)-epicatechin, or epigallocatechin gallate on nitric oxide, endothelin-1, and oxidative stress after nitric oxide production was assessed via the measurement of plasma S-nitrosothiols and plasma and urinary nitrite and nitrate concentrations. The effects on oxidative stress were assessed by measuring plasma and urinary F(2)-isoprostanes. Plasma and urinary concentrations of quercetin, (-)-epicatechin, and epigallocatechin gallate were measured to establish the absorption of these flavonoids.
RESULTS: Relative to water (control), quercetin and (-)-epicatechin resulted in a significant increase in plasma S-nitrosothiols, plasma nitrite, and urinary nitrate concentrations (P < 0.05), but not in plasma nitrate or urinary nitrite. Epigallocatechin gallate did not alter any of the measures of nitric oxide production. Quercetin and (-)-epicatechin resulted in a significant reduction in plasma endothelin-1 concentration (P < 0.05), but only quercetin significantly decreased the urinary endothelin-1 concentration. None of the 3 treatments significantly changed plasma or urinary F(2)-isoprostane concentrations. Significant increases in the circulating concentrations of the 3 flavonoids were observed (P < 0.05) after the corresponding treatment.
CONCLUSIONS: Dietary flavonoids, such as quercetin and (-)-epicatechin, can augment nitric oxide status and reduce endothelin-1 concentrations and may thereby improve endothelial function.
Comparative study of the quercetin, ascorbic acid, glutathione and superoxide dismutase for nitric oxide protecting effects in mouse gastric fundus.
Eur J Pharmacol. 2013 Jan 5;698(1-3):379-87.
Ertu PU, Aydinoglu F, Goruroglu Ozturk O, Singirik E, ÖgÜlener N.
The aim of this work was to compare the preventing capacity of quercetin with Cu/Zn superoxide dismutase (Cu/Zn SOD), ascorbic acid and glutathione on nitric oxide (NO)-induced relaxation in mouse gastric fundus. Furthermore, the effects of the quercetin on the tissue level of total oxidant and antioxidant was investigated. Nitrergic stimulation (4Hz, 25V, 0.1 ms, 10s-train) and exogenous NO (10 μ M) induced relaxation. Pyrogallol (10 μ M), hydroquinone (100 μ M) and LY83583 (6-Anilino-quinolin-5,8-quinone, 5 μ M) inhibited nitrergic relaxations. The inhibition observed with pyrogallol, hydroquinone and LY83583 was prevented by quercetin (0.1 μ M). Also, ascorbic acid (500 μ M), glutathione (100 μ M) and Cu/Zn SOD (100 U/ml) prevented the inhibitory effect of superoxide anion generators on the relaxation to nitrergic stimulation and NO. Diethyldithiocarbamic acid (DETCA; 8mM) inhibited nitrergic relaxations. DETCA-induced inhibition on nitrergic stimulation and NO-induced relaxation was prevented by quercetin, ascorbic acid, glutathione or Cu/Zn SOD. DETCA plus pyrogallol, hydroquinone or LY83583 strengthened the inhibition on the relaxations. Also, pre-treatment with quercetin, ascorbic acid and glutathione prevented the inhibitory effect of DETCA plus LY-83583 on the relaxation to nitrergic stimulation and NO but Cu/Zn SOD did not prevent this inhibition. Also, quercetin increased tissue total antioxidant capacity and decreased tissue oxidant level and oxidative stress index in DETCA-treatment group. These results indicate that quercetin has antioxidant effect and protects NO from endogenous superoxide anion-driven inactivation and enhances its biological activity, suggesting that quercetin may scavenge superoxide anion in a Cu/Zn SOD, glutathione or ascorbic acid-inhibitable manner.
Quercetin, a flavonoid antioxidant, modulates endothelium-derived nitric oxide bioavailability in diabetic rat aortas. Nitric Oxide. 2007 Jun;16(4):442-7.
Machha A, Achike FI, Mustafa AM, Mustafa MR.
The present work examined the effect of chronic oral administration of quercetin, a flavonoid antioxidant, on blood glucose, vascular function and oxidative stress in STZ-induced diabetic rats. Male Wistar-Kyoto (WKY) rats were randomized into euglycemic, untreated diabetic, vehicle (1% w/v methylcellulose)-treated diabetic, which served as control, or quercetin (10mgkg(-1) body weight)-treated diabetic groups and treated orally for 6 weeks. Quercetin treatment reduced blood glucose level in diabetic rats. Impaired relaxations to endothelium-dependent vasodilator acetylcholine (ACh) and enhanced vasoconstriction responses to alpha(1)-adrenoceptor agonist phenylephrine (PE) in diabetic rat aortic rings were restored to euglycemic levels by quercetin treatment. Pretreatment with N(omega)-nitro-l-arginine methyl ester (l-NAME, 10muM) or methylene blue (10muM) completely blocked but indomethacin (10muM) did not affect relaxations to ACh in aortic rings from vehicle- or quercetin-treated diabetic rats. PE-induced vasoconstriction with an essentially similar magnitude in vehicle- or quercetin-treated diabetic rat aortic rings pretreated with l-NAME (10muM) plus indomethacin (10muM). Quercetin treatment reduced plasma malonaldehyde (MDA) plus 4-hydroxyalkenals (4-HNE) content as well as increased superoxide dismutase activity and total antioxidant capacity in diabetic rats. From the present study, it can be concluded that quercetin administration to diabetic rats restores vascular function, probably through enhancement in the bioavailability of endothelium-derived nitric oxide coupled to reduced blood glucose level and oxidative stress.
The effects of quercetin supplementation on body composition, exercise performance and muscle damage indices in athletes.
Int J Prev Med. 2013 Jan;4(1):21-6.
Askari G, Ghiasvand R, Paknahad Z, Karimian J, Rabiee K, Sharifirad G, Feizi A.
BACKGROUND: Flavonoids comprise a large group of plant metabolites, 6,000 of which have been identified to date. Some studies have shown the increased aerobic performance and maximal oxygen consumption (VO2max) and therefore fitness following quercetin intake as a result of elevated number of intracellular mitochondria caused by the flavonoid.
METHODS: This double-blind clinical trial comprised 60 male students having an athletic history of at least 3 years. Body composition, exercise performance, and some blood biomarkers were analyzed. The individuals were selected by convenient sampling, and then were assigned into four groups of equal number by using permuted block randomization. The first to fourth groups received a 500 mg supplemental quercetin capsule plus a 250 mg vitamin C pill, a 500 mg supplemental quercetin capsule plus a 250 mg placebo vitamin C pill, a 500 mg placebo quercetin capsule plus a 250 mg vitamin C pill, and a 500 mg placebo quercetin capsule plus a 250 mg placebo vitamin C pill, respectively, daily for 8 weeks. The participants were asked to continue their routine diet and physical activity during the study and they were monitored through phone calls or text messages.
RESULTS: Lean body mass, total body water, basal metabolic rate, and total energy expenditure increased significantly in the quercetin group after intervention. On the other hand, VO(2max) increased in the “quercetin” and “quercetin + vitamin C” groups following the intervention, non-significantly.
CONCLUSION: Our findings suggest that supplementation with quercetin in athletes may improve some indices of performance.
Quercetin reduces blood pressure in hypertensive subjects.
J Nutr. 2007 Nov;137(11):2405-11.
Edwards RL, Lyon T, Litwin SE, Rabovsky A, Symons JD, Jalili T.
Epidemiological studies report that quercetin, an antioxidant flavonol found in apples, berries, and onions, is associated with reduced risk of coronary heart disease and stroke. Quercetin supplementation also reduces blood pressure in hypertensive rodents. The efficacy of quercetin supplementation to lower blood pressure in hypertensive humans has never been evaluated. We tested the hypothesis that quercetin supplementation reduces blood pressure in hypertensive patients. We then determined whether the antihypertensive effect of quercetin is associated with reductions in systemic oxidant stress. Men and women with prehypertension (n = 19) and stage 1 hypertension (n = 22) were enrolled in a randomized, double-blind, placebo-controlled, crossover study to test the efficacy of 730 mg quercetin/d for 28 d vs. placebo. Blood pressure (mm Hg, systolic/diastolic) at enrollment was 137 +/- 2/86 +/- 1 in prehypertensives and 148 +/- 2/96 +/- 1 in stage 1 hypertensive subjects. Blood pressure was not altered in prehypertensive patients after quercetin supplementation. In contrast, 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. However, indices of oxidant stress measured in the plasma and urine were not affected by quercetin. These data are the first to our knowledge to show that quercetin supplementation reduces blood pressure in hypertensive subjects. Contrary to animal-based studies, there was no quercetin-evoked reduction in systemic markers of oxidative stress.
Quercetin inhibits expression of inflammatory cytokines through attenuation of NF-kappaB and p38 MAPK in HMC-1 human mast cell line.
Inflamm Res. 2007 May;56(5):210-5.
Min YD, Choi CH, Bark H, Son HY, Park HH, Lee S, Park JW, Park EK, Shin HI, Kim SH.
OBJECTIVE AND DESIGN: Mast cell-mediated allergic inflammation is involved in many diseases such as asthma, sinusitis, and rheumatoid arthritis. Mast cells induce production of pro-inflammatory cytokines with immune regulatory properties. We investigated the effect of quercetin on the expression of pro-inflammatory cytokines in human mast cell line, HMC-1.
METHODS: HMC-1 cells were stimulated with phorbol 12-myristate 13-acetate (PMA) and calcium ionophore A23187 (PMACI).
RESULTS: Quercetin decreased the gene expression and production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, and IL-8 in PMACI-stimulated HMC-1 cells. Quercetin attenuated PMACI-induced activation of NF-kappaB and p38 mitogen-activated protein kinase.
CONCLUSION: Our study provides evidence that quercetin may suitable for the treatment of mast cell-derived allergic inflammatory diseases.
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