The health benefits of Quercetin have been recognized for as long as 3,500 years. The people of antiquity put great value on the Quercetin-rich pomegranate juice as an elixir of good health. Nowadays, Quercetin supplements can be purchased at very little expense and can provide enormous benefits to those wanting to heal or optimize their health.
In this post, we will explore the science to reveal the full range of benefits that Quercetin offers, before hinting at the best ways in which you can get extra Quercetin into your diet and supplement regime.
- The Quercetin That I Take
- What is Quercetin?
- Benefits of Quercetin
- 1) Quercetin Protects the Brain
- 2) Quercetin Might Heal Leaky Gut
- 3) Quercetin is Anti-inflammatory
- 4) Quercetin May be Anti-Aging
- 5) Quercetin May Prevent Cancer
- 6) Quercetin Reduces the Histamine Response
- 7) Quercetin is Antibacterial
- 8) Quercetin Limits, and Protects Against, Obesity
- 9) Quercetin May Prevents and Treat Diabetes
- 10) Quercetin Reduces Symptoms of Arthritis
- 11) Quercetin is Good For Your Heart
- 12) Quercetin May Reduce Allergies
- 13) Quercetin Enhances the Immune System
- 14) Quercetin is Good for Athletic Endurance
- 15) Quercetin Reduces Blood Pressure
- 16) Quercetin May Protect the Liver
- 17) Quercetin May Protect the Kidneys
- 18) Quercetin is Good for Circulation
- 19) Quercetin Might Improve Your Sex-life
- 20) Quercetin is an Asthma Treatment
- 21) Quercetin May Protects Your Eyes
- 22) Quercetin May Protect Against Radiation
- 23) Quercetin Works with Resveratrol to Increase Its Effects
- Future Studies
- Dietary Sources of Quercetin
- Buying Quercetin
The Quercetin That I Take
What is Quercetin?
Quercetin belongs to a group of plant pigments, called flavonoids, that give many vegetables and fruits their color. Quercetin is the most widely consumed flavonoid in the human diet (R).
Like all flavonoids, Quercetin demonstrates antioxidant defense by scavenging free radicals and inhibiting oxidation of various molecules. In doing so, Quercetin protects against the negative effects of free radicals, such as cell membrane damage, DNA alterations and cell death (R, R1)
By protecting the body against the damage wrought by these free radicals, Quercetin can protect against a wide range of health conditions that we will now explore.
Benefits of Quercetin
1) Quercetin Protects the Brain
Quercetin protects the brain from toxicity associated with D-galactose. This protection is associated with Quercetin’s ability to increase superoxide dismutase (SOD) activity and decrease levels of malondialdehyde (MDA) (R).
Flavonoids, including Quercetin, inhibit the pro-inflammatory molecules that are associated with many progressive brain disorders. These include: Alzheimer’s disease, viral and bacterial meningitis, AIDS dementia complex, and stroke (R).
Quercetin reverses cognitive deficits in aged and lipopolysaccharide-intoxicated mice (R).
Neuroleptics, used in the treatment of schizophrenia and other brain-related disorders, are often associated with side effects involving movement disorders, similar to Parkinson’s. In mice, pretreatment with Quercetin reduces the side effects of neuroleptic medications (R).
2) Quercetin Might Heal Leaky Gut
Quercetin has also been shown to tighten the junctions between the cells in the gut. In doing so it helps prevent unwanted food particles from entering the bloodstream (R).
Quercetin reverses leaky gut in rodents that are given a substance that induces colon damage (R).
3) Quercetin is Anti-inflammatory
Quercetin decreases pro-inflammatory cytokines which can lead to tissue damage in humans (R).
One study found that men who took Quercetin experienced fewer symptoms of prostatitis – inflammation of the prostate (R).
4) Quercetin May be Anti-Aging
In mice, Quercetin was found to increase exploratory behavior, spatial learning, and memory. These effects were related to Quercetin’s ability to enhance brain functions, limit oxidative stress and increase glutathione levels. The authors conclude that these findings suggest that Quercetin may work as a possible natural anti-aging supplement (R).
Quercetin was found to extend the lifespan and increase stress resistance of worms (R).
A second study confirmed that Quercetin increases the ability of worms to handle stress, both thermal and oxidative while increasing their average lifespan by 15% (R).
However, it is unclear how well these worm studies translate to mammals. A 2013 study found that Quercetin does not extend the lifespan of animals. More research is needed (R).
5) Quercetin May Prevent Cancer
Scientists have long considered Quercetin, and other flavonoids contained in fruits and vegetables, important in cancer prevention. People who eat more fruits and vegetables tend to have a lower risk of certain types of cancer (R).
This fits in with other studies demonstrating the anti-cancer properties of flavonoids that lower TNF-a (R).
Quercetin stops fast reproducing cancer cells when they are in an early, non-productive phase of the cell replication cycle. This freezes tumor growth and also initiates mitochondrial pathways of apoptosis (cell death) (R, R1).
Quercetin enhances the efficacy of conventional chemotherapeutic drugs, like doxorubicin (R).
Some researchers have concluded that Quercetin may be a useful treatment for rare cancers that are resistant to conventional drugs (R).
Giving Quercetin to mice with leukemia led to a 5-fold increase in the life span compared to that of untreated controls (R).
6) Quercetin Reduces the Histamine Response
Quercetin suppresses H1R (Histamine H1 Receptor) gene expression (by suppressing of Protein-Kinase C-δ activation) (R).
7) Quercetin is Antibacterial
Quercetin exerts antibacterial activity against various types of Staphylococcus infections, including antibiotic-resistant S. aureus (MRSA) (R).
Quercetin shows antibacterial activity against the H. Pylori infection (R)
Quercetin inhibits the growth of a wide range of oral bacteria. Therefore, it may be a useful treatment for dental cavities, gum infections and oral mucosa infectious diseases (R).
The antibacterial properties of Quercetin are at least partially attributed to its ability to inhibit DNA gyrase – an important enzyme involved in DNA unfolding (R).
Quercetin offers an effective alternative to the immediate dangers of antibiotic usage and the possibility of a global antibiotic resistance (R).
8) Quercetin Limits, and Protects Against, Obesity
In mice, Quercetin supplementation reduced body weight by nearly 40% and suppressed expression of fat cell metabolism and inflammation-related cytokines (R).
Quercetin inhibits fat accumulation and obesity-induced inflammation in cell studies (R).
In rats, Quercetin reduces obesity-induced skeletal muscle wasting by inhibiting inflammatory receptors and their signaling pathway (R).
9) Quercetin May Prevents and Treat Diabetes
Mice fed on a Quercetin-rich diet for seven weeks showed a reduction in blood glucose levels and blood glycated hemoglobin without any changes in insulin. This was possibly due to the inhibition of small intestine maltase activity (R).
Rats with type-1 diabetes, who were given Quercetin (10-15 mg/kg body weight) for 10 days, showed significantly lowered blood sugar levels (R).
One cell study analyzed the effects of ten compounds present in berries on glucose uptake. Two forms of Quercetin (Quercetin-3- O-glycoside and Quercetin aglycone) were the most potent compounds for regulating glucose uptake via the AMPK pathway (R, R1).
10) Quercetin Reduces Symptoms of Arthritis
There are reports of people with Rheumatoid Arthritis who had fewer symptoms when they switched from a typical Western diet (meat heavy) to one with lots of berries, fruits, vegetables, nuts, roots, seeds, and sprouts containing Quercetin and other antioxidants (R).
A cell study found that Quercetin inhibited neutrophil activation and synoviocyte proliferation – two key factors in the development and proliferation of arthritis (R).
Quercetin has a key advantage over conventional arthritis drugs (such as methotrexate and paclitaxel) in that it doesn’t cause serious systemic toxicity (R).
11) Quercetin is Good For Your Heart
Daily doses of Quercetin reduces systolic blood pressure (R).
Quercetin-rich supplementation from onion peel extract improved blood lipid profiles, glucose, and blood pressure – all of which are important factors in heart health (R).
Regular Quercetin supplementation provides beneficial effects on blood lipid behavior, especially in cigarette smokers who are exposed to a high degree of oxidative stress and are particularly susceptible to the development of coronary heart disease (R)
Lastly, a study found that 500mg of Quercetin per day significantly reduced HDL cholesterol (R).
12) Quercetin May Reduce Allergies
Lactose, eggs, peanuts, fish, wheat, shellfish, tree nuts, and soy can all trigger an immunoglobulin E (IgE) allergic response (R).
Quercetin is a potent suppressor of IgE allergic responses and, therefore, should be used as an alternative medicine to treat IgE-mediated food allergies (R).
Mast cells, which are activated during an allergic response, promote inflammation by releasing molecules such as histamine, leukotrienes, cytokines chemokines, and neutral proteases. Quercetin inhibits human mast cell activation by controlling the amount of calcium that enters each cell (R).
The histamine H1 receptor (H1R) gene is up-regulated in patients with allergic hay fever. The level of H1R expression correlates with the severity of allergic symptoms. Quercetin inhibits the up-regulation of histamine H1 receptor (R).
13) Quercetin Enhances the Immune System
Clinical trials have shown that Quercetin reduces susceptibility to viral illnesses (R).
Because they stretch their bodies to exhaustion so frequently, endurance athletes are more susceptible to getting sick than normal people. One study showed taking 1000 milligrams of Quercetin a day protected cyclists from developing exercise-induced respiratory infections following heavy training (R).
14) Quercetin is Good for Athletic Endurance
In just seven days, Quercetin supplementation (500mg taken twice per day) increased endurance without exercise training (R).
15) Quercetin Reduces Blood Pressure
Quercetin improves the function of endothelial cells and vascular smooth muscle, which are responsible for governing blood pressure (R).
16) Quercetin May Protect the Liver
Treatment with Quercetin, prior to receiving toxic amounts of ethanol, protected the liver of rats against oxidative stress by neutralizing the products of lipid peroxidation and increasing the production of the antioxidant Glutathione (R, R1).
Quercetin can mitigate acetaminophen-induced liver toxicity by reducing reactive oxygen and nitrogen species (R).
Rats with diet-induced liver damage that were then given Quercetin showed decreased levels of liver damage enzymes, lipoperoxidation, DNA damage and a lower degree of overall inflammatory processes (R).
Quercetin protects against obesity-induced fatty liver disease by stimulating mitochondrial oxidative metabolism in the liver (R).
17) Quercetin May Protect the Kidneys
Quercetin reduces damage done to the kidneys of rats that are administered toxic substances, such as chemotherapy drugs (R).
A compound called Fe-NTA induces significant oxidative stress in the kidneys. Quercetin substantially reduces kidney dysfunction and structural changes while restoring depleted kidney antioxidant enzymes (R).
18) Quercetin is Good for Circulation
Quercetin improves the health of your blood vessels by increasing the products of nitric oxide and reducing endothelin-1 concentrations (R).
19) Quercetin Might Improve Your Sex-life
Oxidative stress is a primary cause of erectile dysfunction (inability to get or maintain an erection). Quercetin treats erectile dysfunction by reducing levels of oxidative stress in diabetic mice (R).
20) Quercetin is an Asthma Treatment
21) Quercetin May Protects Your Eyes
Quercetin reduces the risk of cataracts by acting on a number of pathways that play important roles in eye lens function (e.g. oxidative stress, non-enzymatic glycation, and epithelial cell signaling) (R).
Retinal cells are found at the back of your eye and act as light receptors, playing an important role in setting the color, resolution, and brightness of your vision. Quercetin has a protective effect on retinal cells (R).
Aldose reductase (AR) is an enzyme that can accumulate in the lenses of people with consistently high blood sugar, such as diabetics, and cause significant eye problems. Quercetin can limit the negative consequences of high AR on eyes (R).
In animals, Quercetin enhances lens clarity (R).
Finally, The National Eye Institute found that Quercetin behaves as a powerful antioxidant and prevents inflammation in eye tissues (R).
22) Quercetin May Protect Against Radiation
Quercetin mitigates the damage done to the skin of rodents that are exposed to X-ray radiation, which would otherwise induce skin fibrosis (R).
23) Quercetin Works with Resveratrol to Increase Its Effects
The combination of quercetin and resveratrol, a compound/polyphenol from grapes, can also have more health benefits. For example, they combine their effects together to inhibit colon cancer and increase cancer cell death (apoptosis) in human cell culture (R).
In rats, this combination also significantly reduced fat tissue. In contrast, resveratrol or quercetin alone did not have any effect on the fat tissue. The combination of resveratrol and quercetin is synergistic (R).
As mentioned, Quercetin lowers TNF-a. High TNF-a levels are associated with the following diseases: Crohns, Alzheimers, Rheumatoid Arthritis, Psoriasis and Ankylosing Spondylitis. Antibodies raised against TNF-α are now commercially available under prescription and are proving beneficial for many patients.
Because of the inpact of Quercetin on TNF-a it is likely that further studies will emerge showing that Quercetin is beneficial for a whole range of health conditions.
Quercetin is a safe, natural supplement that you can use as a primary therapy or in conjunction with conventional methods (R).
However, there have been a small number of reports indicating that Quercetin can act as a thyroid disruptor. Thus, you should think carefully when considering its supplemental and therapeutic application in those with existing thyroid irregularities (R).
Quercetin Has Toxic Effects on Neurons
While quercetin has antioxidant effects, not enough is known about its effects on healthy cells. In rat nerve cells, quercetin treatment for 24 hours can cause cell death (R).
The nerve cells died in a concentration dependent manner. This means that more cells died when the concentration of quercetin was higher. Additionally, the cells died in an equal manner of apoptosis (programmed cell death) and necrosis (death due to injury or disease) (R).
The results of this study indicate that more caution is required when using quercetin for treating health problems (R).
Quercetin Increases Homocysteine Levels
Homocysteine is a product of protein metabolism. High concentrations of homocysteine are associated with strokes and heart attacks. In human liver cancer cell culture, quercetin significantly increased homocysteine concentration (R).
This increase in homocysteine outside of the cells (extracellular) may be related to increased methylation. Thus, people should be more cautious when using quercetin supplements (R).
Dietary Sources of Quercetin
Quercetin is found in a large number of foods. How the food was grown and transported will impact the concentrations of Quercetin (R).
You can enhance the absorbability of Quercetin by combining it with glucose. Thus, sugary fruit like apples and blueberries are probably a good bet for a natural Quercetin source (R).
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