Last updated on May 6th, 2023 at 06:06 am
Oxidative stress is one of those stressors that often go unnoticed and can cause several health issues. It can lead to problems such as DNA damage, blood sugar imbalances, and alterations in hormone secretion, all of which can be controlled by increasing the levels of antioxidants in the body. Antioxidants are molecules that can counteract the effects of free radicals and reduce the stress of oxidation on the body. They are present in nutrients such as vitamins, essential minerals, and flavonoids. Flavonoids are phytonutrients that are responsible for the bright colors found in fruits and vegetables and are known for their wide-ranging health benefits due to their anti-inflammatory and antioxidant properties. These benefits include cancer prevention, longevity, diabetes management, weight management, and the prevention of neurodegenerative diseases. One of the most well-known flavonoids is quercetin.
What is Quercetin?
The word quercetin is derived from the Latin word quercetin, which means Oak forest. Quercetin is named as such because acorns and oak trees are rich sources of quercetin. As a flavonoid (natural plant pigment), quercetin is present in many vegetables, fruits (especially citrus fruits), seeds, and foods, including onions, buckwheat, flowers, barks of certain trees, apples, berries, and green tea.
Quercetin, also known as vitamin P, has a bitter taste and is used in dietary supplements, beverages, and packaged food for its health benefits. As it is one of the most common flavonoids, it is not hard to find in our daily foods, which can contain up to 50 milligrams of quercetin. In the body, it metabolizes at a very high rate and stays in the body for less than 24 hours after ingestion.
In plants, it is a naturally occurring polar auxin transport inhibitor and regulates the transport of the hormone auxin from one region to another. For humans, quercetin acts as an antioxidant and anti-inflammatory substance, which reduces and manages free radicals by giving them some of its electrons to shut off the oxidative activity of free radicals. If left unchecked, free radicals cause a chain reaction leading to cell damage. Quercetin’s antioxidant properties may help in heart conditions, blood sugar management, cancer management, and inflammation-induced swelling.
Quercetin Benefits
Antioxidant Property of Quercetin
In several studies, quercetin has shown high antioxidant potential, which is higher than other nutrients, including Vitamin C, Vitamin E, and Carotene. It can act as a protective agent against the harmful effects of nicotine abuse, smoking, and tobacco use. Quercetin can relieve Oxidative stress on the body, which damages cells and causes inflammation and severe health problems. The antioxidant activity of quercetin promotes cell repair, prevents DNA damage, and provides a shield against radiation-induced damage.
Quercetin for weight management
Flavonoids have been studied for their various health benefits, including weight loss. Among them, quercetin is a flavonoid that has been reported to aid in weight loss and obesity management.
An animal study involving obese rats showed that quercetin supplementation for 8 weeks led to a significant reduction in weight compared to obese rats not given quercetin.
Quercetin has also been shown to increase the rate at which the body burns excess fat during exercise or while consuming fewer calories. In the same study, quercetin demonstrated hunger-suppressing properties.
Although studies on quercetin and its effectiveness in weight management are promising, more research is needed to establish quercetin as a standalone weight management approach. However, quercetin can be blended with other ingredients to enhance its weight-loss effects. Multiple weight management supplements contain quercetin along with other ingredients.
Quercetin for Allergies
Quercetin acts as a natural antihistamine and suppresses the production of histamines by the mast cells present in the connective tissues, which get triggered by allergens. The natural antihistamine property of quercetin makes it extremely useful in the treatment of allergic diseases, including asthma, bronchitis, rhinitis, etc. Quercetin prevents allergic reactions caused by the environment and allows the body to use its resources better.
Quercetin used for Infections
Quercetin is an antiviral and antibacterial flavonoid that is especially effective against bacteria that affect digestion, kidney function, skin, and lungs. It stops bacteria from replicating, and this function of quercetin is also effective against viruses that stop multiplying under the influence of quercetin, which prevents cytokines and leukotrienes production.
Viruses and bacteria that quercetin seems to stop from replicating are:
- Bacteria
- Heliobacter Pylori (causes gastritis and ulcers)
- Salmonella enteritidis (causes food poisoning)
- Staphylococcus aureus (causes staph infection)
- Escherichia coli (causes food poisoning and UTI)
- Proteus (causes UTI)
- Aspergillus flavus (causes arthritis)
2. Viruses
- Adenovirus
- Herpes simplex virus
- Japanese encephalitis virus
- Respiratory syncytial virus
Quercetin also shows scavenging activity (in vitro) against the HIV-1 virus and prevents it from causing infection. Quercetin achieves this by inhibiting reverse transcriptase and protease activity of the HIV-1 virus which is how the virus affects the patient’s DNA.
Quercetin used for Cardiovascular Health
Our health is affected by what we eat, and quercetin is part of a healthy diet that affects all of our body and its organs. A quercetin-rich diet is not only healthy but also has heart-protective properties.
Quercetin stops fat cell accumulation and maturation and promotes apoptosis (cell death) in already-matured fat cells. In many studies, quercetin has been shown to lower the risk of hypertension, heart attacks, endothelial dysfunction, and death caused by low-density lipoprotein. In a research study done in Greece, quercetin showed the potential to reverse the effects of coronary heart disease and stopped its progression by improving blood flow in the arteries.
Quercetin used for the Brain
Oxidative stress-induced brain damage is caused by free radicals, and if left unchecked, it leads to Alzheimer’s, Parkinson’s, and even strokes due to neuronal damage. Quercetin, along with other flavonoids, is being tested for neuroprotective properties as quercetin is a known antioxidant and may possibly be used as a prophylactic against brain injury due to oxidative stress.
Due to its neuroprotective properties quercetin can be used to help in vision impairment caused by a damaged optic nerve.
However, the effects of quercetin on brain function and as a neuron protector have yet to be fully studied.
Quercetin used for Cancer
Several studies have linked certain cancers (like colon cancer) to lifestyle and diet, and in those cases, the anticancer properties of quercetin can help manage the effects of lifestyle-related cell damage to some degree.
In one study, the anti-tumor activity of quercetin, in combination with other phytonutrients, decreased and reduced the size of tumors in the rectum and small intestine.
Quercetin also seems to trigger apoptosis, which is one of its anticancer properties. It is extensively being studied for its anticarcinogenic activities, and as more research comes out, we will see an increase in the use of quercetin for cancer and tumor treatment.
Quercetin Food Sources
Quercetin is present in many foods which are part of our daily diet.
- Quercetin Sources: Broccoli, Green Tea Leaf, Capsicum, Acerola Cherry, Kale, and Asparagus.
- Quercetin Blend: Green tea, oranges, acerola cherries, and oranges can be included in the natural quercetin blend.
Dosage
Up to 1500 mg/day (orally)
Quercetin can be taken three times a day in 500 mg doses orally for its general health benefit.
Up to 1400 mg/week (intravenous)
In certain conditions, like cancer, where quercetin is needed to be released quicker, it can be taken intravenously with a dosage limit of around 1400 mg for one week.
Quercetin Side Effects
Quercetin is a flavonoid that is already present in our foods, and we consume around 30mg of it on average. However, if you are taking quercetin as a supplement for its health benefits, use it within the recommended dose as mentioned on the supplement or consult your doctor.
Some known side effects of quercetin are:
- Headaches
- Numbness
- Tingling
- Shortness of breath
- Nausea and vomiting
- Kidney damage (can happen if taken intravenously in doses greater than 945 mg/m2)
Drug Interaction Warning
Quercetin supplements should not be taken with certain drugs, including everolimus and topotecan. If you are on medication for any disease, consult your doctor or take proper guidance before starting quercetin.
Takeaways
Quercetin is a flavonoid found in many fruits and vegetables that can act as an antioxidant and anti-inflammatory substance in the body. It has numerous health benefits including relieving oxidative stress, managing blood sugar levels, and reducing inflammation in the body. Quercetin can also act as a natural antihistamine, suppress histamine production and prevent allergic reactions, and it is effective against various bacterial and viral infections. Additionally, quercetin has been shown to promote cardiovascular health and may have neuroprotective properties. Quercetin and its supplements can be taken for all these benefits without any major side effects.
