How much quercetin

It also showed quercetin could protect against the toxic effect of certain metals on the nervous system. Research suggests that quercetin might be an effective antihistamine, as it restricts histamine from being released from cells. These anti-allergy properties indicate that quercetin might help treat bronchitis and asthma.

Quercetin has antibacterial properties, which are effective against almost all types of bacteria, particularly those linked to:. Diet plays an essential role in reducing the risk of cardiovascular diseases, such as heart disease and strokes. Because fruit and vegetables contain flavonoids, eating more of them can reduce the risk of these diseases. Quercetin may improve blood vessel cell health and blood flow through arteries in people with heart disease.

According to a study by the American Heart and Stroke Association, taking quercetin supplements could be an effective way to reduce blood pressure. Other research showed that people who were overweight and took a quercetin supplement of milligrams mg per day had lower levels of harmful cholesterol in their blood, as well as reduced systolic blood pressure, which measures the pressure in the blood vessels during a heartbeat. Onions have the highest level of quercetin compared to other tested produce, containing approximately mg per kilogram.

If people take quercetin as a supplement, the most common dose is mg per day , but some people can take up to 1, mg per day. Supplements may also include other substances, such as bromelain or vitamin C, which may help the body absorb quercetin more effectively.

The natural antioxidants found in fruits and vegetables can be very beneficial when consumed as part of a balanced and nutritious diet. Some people reported minor side effects when taking high doses of quercetin, such as 1, mg per day, long-term. Quercetin may interact with some medications, so people should ask their doctor before taking a supplement. Quercetin is a flavonoid found in fruit and vegetables. It has a wide range of benefits, which people can get by including a variety of fruit and vegetables in their diet.

Side effects may include headache and upset stomach. Preliminary evidence suggests that a byproduct of quercetin can lead to a loss of protein function. Very high doses of quercetin may damage the kidneys. You should take periodic breaks from taking quercetin. If you are being treated with any of the following medications, you should not use quercetin supplements without talking to your health care provider first.

There is some concern that quercetin may reduce the effectiveness of certain antibiotics. Speak with your doctor. Quercetin may enhance the effect of these drugs, increasing your risk for bleeding. Anticoagulants include:. Test tube and animal studies suggest that quercetin may enhance the effects of doxorubicin and cisplatin, which are two chemotherapy medications used to treat cancer.

In addition, some doctors believe taking antioxidants at the same time as chemotherapy can be harmful, while others believe it can be helpful. In one study, combining quercetin with the anti-tumor drug doxorubicin, increased the drug's beneficial effects on breast cancer cells. In another, taking quercetin alongside cisplatin reduced the medicines' therapeutic effects in ovarian cancer cells.

Talk to your oncologist before taking any supplements if you are undergoing chemotherapy. Quercetin may interfere with the body's absorption of this drug, which is used to suppress the immune system.

Since quercetin affects the liver, concomitant use with medications that are changed by the liver may alter how the body metabolizes these medications. Speak with your physician. Health effects of quercetin: from antioxidant to nutraceutical. Eur J Pharmacol. The quercetin paradox.

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Protective effect of quercetin against arsenite-induced COX-2 expression by targeting PI3K in rat liver epithelial cells. It is generally considered safe for most people, but pregnant women, breastfeeding women, and people with kidney disease should avoid it. Quercetin can interact with antibiotics or blood thinners, so it might be wise to talk to a healthcare provider first.

Foods that have quercetin include apples, onions, red wine, tea, and berries. It can also be found in the herbs ginkgo biloba and St. Quercetin intake should never exceed one gram per day, since more than that amount can cause kidney damage. When taking a dietary supplement, always follow the guidelines on the product packaging. Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life.

Memorial Sloan Kettering Cancer Center. Updated December 6, Quercetin and its anti-allergic immune respons e. Effects of quercetin on blood pressure: a systematic review and meta-analysis of randomized controlled trials. J Am Heart Assoc. Quercetin and endurance exercise capacity: a systematic review and meta-analysis.

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