Enhanced Antioxidant Protection -- Heart Disease, Cancer, Allergies, and More - Page 2
By Julius Goepp, MD
Researchers in both Brazil10 and Korea11 protected animals from fatal allergic reactions to common food allergens by pre-treating them with quercetin in oral or inhaled forms.
Quercetins ability to prevent allergic effects has tremendous implications for the treatment and prevention of asthma and bronchitis, conditions for which quercetin-rich foods have had long traditional roles.12 Several studies since 2007 have shown that animals pre-treated with quercetin or related compounds have dramatically reduced side effects to chemicals that trigger asthma attacks.13-15
In a dramatic study in 2008, Korean researcher Hee Moon compared inhaled quercetin head-to-head with prescription asthma drugs in guinea-pigs.16 Remarkably, the nutrient-derived quercetin treatment reduced airway resistance (difficult breathing) more than the adrenaline-like drug albuterol and had equivalent effects to the anti-inflammatory cromolyn as well as the potent steroid dexamethasone.
In a form of epidemiological detective work, nutrition scientists from Michigan State University explored the impact of dietary flavonoids such as quercitin in their more general roles as systemic anti-inflammatory agents. Basing their work on knowledge that intake of certain foods can lower levels of the inflammatory risk factor C-reactive protein (CRP), they went looking for the most potent food components, studying more than 8,000 adults. They found that higher flavonoid intake was associated with lower CRP levels and quercetin headed the list of specific flavonoid compounds that had the strongest protective effect. Since elevated CRP levels are associated with numerous disease states such as obesity, heart disease, and lupus, this provides compelling reason to explore its potential for preventing death and disability from a host of major killers.Immune-Modulating Effects
Quercetin is one of nearly 200 beneficial compounds found in garlic18 which has been used for millennia in treating and preventing infectious disease such as viral syndromes.19 Indeed, modern science confirms its benefits in helping fight off viral invaders and their side effects.
In laboratory studies, quercetin has been found to reduce the replication and infectivity of numerous viruses, including respiratory syncytial virus (a common cause of childrens upper respiratory infection) and para-influenza virus type 3.2
Italian researchers just last year showed that they could use a quercetin-rich extract to up-regulate the antiviral immune response in cells infected with herpes viruses.20 Additionally, an animal study last year showed that supplementation with quercetin helped protect mice against influenza infection following exercise-induced stress.21 These findings make quercetin an intriguing candidate for preventing and managing viral infections in susceptible individuals.Obesity
The rampant rise of obesity poses one of the greatest global health threats today. Scientists are now eagerly exploring quercetins potential as a means of controlling fat accumulation.
Fat, long considered to be an inert and biologically uninteresting tissue, is now known to be a virtual beehive of metabolic and endocrine activity. It helps produce a myriad hormones, inflammatory cytokines, and other molecules that influence health for better or for worse.22 Fat tissue mass is essentially the product of new fat cells, their accumulation of fat triglycerides (blood fats), and their programmed death (apoptosis).23 Each of these processes can be affected by various natural dietary components. As University of Georgia nutritionist Srujana Rayalam recently observed, Therapy employing compounds that target different stages of the adipocyte [fat cell] life cycle might prove beneficial for decreasing adipose tissue volume by inducing apoptosis or by inhibiting adipogenesis [fat accumulation] or both.23 What is so exciting about quercetin is recent evidence that this flavonoid, alone or in combination with resveratrol and genistein, is capable of exerting just such multiple effects directly on fat tissue.
Quercetin inhibits fat accumulation in maturing human fat cells in culture, for example, while also suppressing the maturation of new fat cells and simultaneously triggering apoptosis (programmed cell destruction) in existing fat cells.24,25 Quercetin actually blocks the uptake of glucose from the blood, depriving fat cells of the raw material they need to manufacture and accumulate fat molecules.26 In remarkable work published in 2008, the University of Georgia group found that while they could block fat cell production and enhance fat cell death dramatically using either quercetin or resveratrol (another powerful flavonoid) alone. When they used the two in combination they decreased lipid (fat) accumulation in cultured fat cells by nearly 70% while increasing fat apoptosis by a whopping 310%. 27
Just a few months later, the same research team found that resveratrol and genistein synergize with quercetin to decrease lipid accumulation in human fat cells. While genistein, quercetin, and resveratrol decreased lipid accumulation in fat cells by 17%, 20%, and 17%, respectively, the combination of all three agents decreased lipid accumulation by an impressive 80%.25
Studies in animals lend support to the potential anti-obesity effects of quercetin. In mice fed a high-fat diet, quercetin produced a transient increase in energy expenditure,28 while another study showed that high-dose quercitin supplementation was associated with reduced body weight gain in obese, insulin-resistant mice.3
Its no surprise that quercetin, alone or in combination with other nutraceuticals, is drawing the attention of researchers searching for novel strategies for fighting obesity via numerous mechanisms.
In 2004, British researchers demonstrated that humans who took quercetin supplements had substantially reduced platelet aggregation, suggesting that another of its cardiovascular health benefits was related to a reduced risk of clotting.30 These researchers later showed that dietary ingestion of quercetin from onion soup also helped inhibit platelet aggregation.31 And, in a study of 30 men who already had coronary heart disease, Greek cardiologists showed that a red grape polyphenol extract rich in quercetin caused an increase in flow-mediated dilation of major arteries, a potent indicator of improved endothelial health.32
The natural next step was to study quercetin supplements alone and their effect on blood pressure -- a study undertaken at the University of Utah in 2007.33 They studied 19 patients with pre-hypertension and 22 with stage 1 (early) hypertension, supplementing them with placebo or 730 mg quercetin/day for 28 days. There was no effect on the pre-hypertensive patients but the hypertensive group enjoyed reductions in both systolic and diastolic blood pressure (average 7 mmHg and 5 mmHg reductions, respectively) ... meaningful changes that lower vascular disease risk.
In 2008, a randomized, placebo-controlled crossover trial in 12 healthy men showed biochemical evidence of improved endothelial function (such as augmentation of nitric oxide status) with as little as 200 mg/day of quercetin.34
Together, these effects point to an important role for quercetin in protecting cardiovascular health.
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