Quercetin in Detail

Red Onions are rich in Quercetin. These onions are especially high in Quercetin, a bioflavonoid. These are what give apples their color. Onions, garlic, tea, red grapes, berries, broccoli, and leafy greens are also rich sources of quercetin. Bioflavonoids are water-soluble compounds. In humans, bio-flavonoids maintain resistance of capillary walls to permeation and change of pressure, and have synergistic antioxidant effects with vitamin C.

What Experts have to say about Quercetin:

“Indicators suggest quercetin may help performance in athletes and may help also improve our cognitive performance, or brain alertness. I strongly encourage you to look into quercetin.”
-Dr. Daniel Johnston Preventive Medicine, Department of Defense, US Military, Comprehensive Soldier Fitness

 “Quercetin exerts strong anti-oxidative, anti-inflammatory, anti-pathogenic, and immune regulatory effects in vitro and in animal-based studies. Epidemiological data indicates reduced rates of cardiovascular disease and various types of cancer in groups self-selecting diets high in Quercetin. In human studies, quercetin has shown to lower blood pressure, and in athletes it significantly reduces the incidence of the common cold, especially during periods of heavy training and race competition" 
-Dr. David Nieman Director, Human Performance Lab - North Carolina Research Center

 “Quercetin is a most promising compound for disease prevention and therapy.” - German Nutrition Expert Dr. Stephan Bischoff

DARPA researchers have identified a very safe, natural antioxidant – called Quercetin – and developed it into a new form that is now available to the military and the general public.

 Among Quercetin’s many potential benefits is illness prevention. In a randomized, placebo-controlled study, Quercetin helped prevent viral illnesses, like colds and flu, after physical exertion. Following a strenuous 3-day exercise routine, 50 percent of the control group became ill with colds and flu, whereas only five percent of the Quercetin supplemented group did. This important immune protective effect will help keep our war fighters healthy during training and deployment. Tony Tether Director, DARPA Quercetin, besides inactivating cancer-causing agents, inhibits enzymes that spur cancer growth. It also has anti-inflammatory, anti-bacterial, anti-viral and anti-fungal activity.
Quercetin is a powerful anticancer substance by several mechanisms. It is cytotoxic (kills cancer cells) by inhibiting the transport of lactate out of anaerobic cancer cells. This causes the cancer cell to become more acidic and die (apoptosis.)

Cancers generate consume large amounts of glucose, starving the body. From this glucose they generate lactic acid which poisons the body. The liver combats this by converting the lactic acid back into glucose which feeds the tumor again in a kind of snowballing effect. Quercetin helps prevent the tumor from releasing lactate in the first place.

Among other antitumor effects are: 

• Arrest of cell progression at the G1/S and G2/M interphase
•  suppression of glycolysis and ATP production
•  interference with ion pump systems
•  interference with various signal transduction pathways
•  and inhibition of DNA polymerase B and I.

It was also found that Quercetin blocks androgen (male hormone) receptors and in a study caused a dramatic reduction in two androgen-regulated tumor markers, including PSA, the marker for prostate cancer. The author, Dr. Xing said that it could be “a chemopreventive and/or chemotherapeutic agent for prostate cancer.”

It’s well known to nutritional scientists as a potent free radical-scavenger (Murakami 2008). Quercetin also happens to possess a singular cancer-fighting feature: it can prevent cancer caused by chemicals. Its unique molecular structure enables it to block receptors on the cell surface that interact with carcinogenic chemical compounds. This makes it a perfect anticancer agent for the colon, where carcinogenic chemicals tend to accumulate (Murakami 2008).

Researchers in Greece have also discovered that quercetin dramatically suppresses one particular cancer-causing gene in colon cells. This makes quercetin supplementation an ideal form of early prevention for individuals with a family history of colon cancer (Psahoulia 2007).

Dutch scientists uncovered even more evidence of its cancer-preventive power at the genetic level. In an animal study, quercetin reduced “cancer gene” activity and increased “tumor-suppressor gene” activity in colon cells after 11 weeks (Dihal 2008).

In yet another promising animal study, scientists in South Carolina were able to halt the development of aberrant crypts. Cancer-prone rats fed a diet high in quercetin (Mahmoud 2000) underwent a four-fold reduction in the number of aberrant crypts compared to a control group. Similar research has yielded additional evidence of quercetin’s capacity to reduce emerging aberrant crypts — a vital first step in preventing colon cancer from developing at all (Gee 2002).

In 2006, scientists at the Cleveland Clinic evaluated patients suffering from familial adeno-matous polyposis. They discovered that a combination of curcumin and quercetin could cause these growths to diminish substantially. The researchers supplemented the patients with 480 mg of curcumin and 20 mg of quercetin orally, three times a day, for six months. Every single patient experienced a remarkable decrease in polyp numbers and size, with average reductions of 60% and 51%, respectively (Cruz-Correa 2006).

Here is an PubMed article published in NCBI about how Quercetin can help in Cancer Cachexia- Click Here.

More details of Quercetin benefits- Lifeextension Article