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Quercetin can also help regenerate blood vessels to improve blood flow, which supports healthy heart function. Only a limited number of human studies have evaluated the effects of quercetin on obesity treatment, but the results are promising.

In one small study, six men and 30 women who were overweight or had obesity were randomly assigned to take either milligrams mg of quercetin or a placebo every day for 12 weeks.

The researchers found that the quercetin group had significant decreases in weight; body mass index; and waist, hip, and thigh measurements. The quercetin group also had a reduction in overall body fat percentage, particularly in the arms. More research—especially in larger numbers—would be needed to say for certain the effect quercetin can have on weight loss or how quercetin would fit into an overall weight management plan.

Over time, it destroys memory and thinking. Flavonoids, the family of antioxidants to which quercetin belongs, have been extensively studied for their antioxidant and anti-inflammatory activities—both of which are important in the prevention of Alzheimer's.

Research has shown that flavonoids as a whole may be able to help prevent the development or progression of Alzheimer's.

Research on how the flavonoid quercetin affects Alzheimer's has been primarily animal-based. But one study in humans looked at the impact of quercetin-rich onion powder on cognitive function in 70 healthy Japanese adults aged The participants were randomly assigned to consume either 11 grams of air-dried, high-quercetin onion powder or a placebo daily for 24 weeks.

The results showed quercetin-rich onion powder may delay cognitive decline in older adults with early stage Alzheimer's. The researchers also found the quercetin group experienced better cognitive function scores, improved depressive symptoms, and increased overall motivation.

Studies regarding quercetin and immune function have had mixed results, but there is some promise that the flavonoid can support immune function. In one trial, 1, participants took mg or 1, mg of quercetin or a placebo each day for 12 weeks. Overall, quercetin supplementation did not have a significant effect on rates of upper respiratory tract infections, such as colds , compared with the placebo.

However, in a subgroup of participants aged 40 or older who rated themselves as physically fit, 1, mg of quercetin per day resulted in fewer total sick days and a reduced severity of upper respiratory tract infection symptoms.

Another small study among athletes found that supplementing with mg of quercetin per day did not impact several measures of immune function after three days of intense exercise, but it did significantly reduce upper respiratory tract infection risk.

In the two-week period after the exercise sessions, just one out of 20 participants in the quercetin group got sick compared to nine of 20 in the placebo group. One of those studies looked at the effect that a product made from quercetin and sunflower lecithin—which increases the rate of quercetin absorption by up to 20 times compared to pure quercetin—had on people with COVID The National Institutes of Health NIH included quercetin in its review of supplements for COVID Some of these conditions include rheumatoid arthritis RA , inflammatory bowel disease, multiple sclerosis , and lupus.

Due to its protective anti-inflammatory and antioxidant abilities, quercetin may help prevent or manage autoimmune conditions. For example, in one small study, 50 women with RA were randomly assigned to receive either mg of quercetin or a placebo every day for eight weeks.

The quercetin group experienced significant reductions in early morning stiffness, morning pain, and post-activity pain compared with the placebo group.

In addition, the number of patients with active RA disease in the quercetin group significantly decreased. women of reproductive age. People with PCOS have higher levels of the male hormone androgen than people with female reproductive systems usually have.

The levels of androgen can lead to several symptoms, including a stop in ovulation. This can increase the risk of type 2 diabetes. A limited number of human studies have looked at the impact of quercetin supplements vs. a placebo on PCOS for up to 12 weeks. So far, the research has shown positive outcomes, with quercetin users experiencing improvements in both hormone and insulin regulation.

However, scientists say there are not enough studies to make strong conclusions about the use of quercetin supplements for PCOS. While quercetin can be taken in supplement form, it is also naturally found in a variety of plant foods.

Fruits, vegetables, herbs, and beverages are all potential sources of quercetin. Here are examples of foods and drinks that might be good natural sources of quercetin:.

Queretin is taken in naturally through the food, drinks, and herbs you consume. If you are taking supplementary quercetin, it's possible to use it topically, intravenously, and orally. Most people take quercetin orally, through a supplement capsule you'd buy at the store. Tthere is no recommended daily quercetin intake for general health, wellness, or disease prevention.

It's typically used in doses of , mg daily for up to 12 weeks. Worth noting is that fruits and vegetables are the major sources of quercetin, and the Dietary Guidelines for Americans advise adults to consume 1. When used as an ingredient in food and drinks, quercetin is believed to be safe in amounts up to mg per serving, according to the U.

Food and Drug Administration FDA. Currently, it is only known that up to 1 gram of quercetin supplements a day for 12 weeks has been considered safe.

More research on longer use and higher doses is needed. People with kidney problems should avoid quercetin—especially when administered through the vein—since the supplement can make kidney issues worse. It's unknown how safe quercetin is for people who are pregnant or breastfeeding, so these groups should also avoid the supplement.

Quercetin supplements may interact with some medications. For instance, quercetin might reduce blood pressure in people with high blood pressure, so the supplement could increase the effects of medications used to treat the condition, lowering blood pressure too much.

Quercetin might affect other medications, including Pravachol pravastatin, used to treat high cholesterol and Allegra fexofenadine, an antihistamine used to manage allergy symptoms. Many of the studies on how quercetin interacts with other medications were done on animals or in test tubes.

If you are taking any medication, talk with your healthcare provider about any potential risk there is before starting quercetin. As with any supplement, quercetin isn't regulated by the FDA.

To ensure what you are buying was manufactured correctly, is true to the ingredient list, and doesn't contain harmful levels of contaminants, purchase a product that has been third-party tested.

Reputable third-party testing organizations include ConsumerLab, NSF International, and U. Kidney damage has been reported but only with the use of intravenous quercetin in large amounts. It's unknown how safe large doses or long-term use of oral quercetin supplementation is.

Generally, quercetin is considered to be safe when gotten naturally through food and drinks. Quercetin works in synergy with other immune-supporting nutrients, including vitamins C, D, E and zinc.

Quercetin is a zinc ionophore, which means that it helps zinc enter into cells so that it can carry out its antiviral activity.

Vitamin C, as well as being a well-known nutrient itself for supporting immunity, increases how much quercetin we can absorb via our gut. Most, if not all, of the studies into the effects of quercetin on the immune system have used it in supplement form.

However, because quercetin is so widely distributed throughout the plant kingdom, you can get useful amounts from your diet. Small dietary changes can increase the amount of quercetin you consume.

The main food sources of quercetin include:. Red apples contain much more quercetin than green apples, as the pigment is a sign of quercetin being present. Therefore, when choosing an apple, choose the rosiest for you can find for more quercetin!

For the same reason, red onions and spring onions contain more quercetin than brown or white onions. Frying, roasting or baking onions increases the quercetin content.

Interestingly, onion skins can contain almost 50 times more quercetin than the flesh. If you really want to increase the quercetin in your diet, you can save your onion skins and put them in a herb bag which you can add to stews and soups while cooking.

Just remember to remove the bag before serving! Eating a diet based on a wide variety of fresh plant foods should ensure that you consume plenty of quercetin. Through the genius of Mother Nature, quercetin in food form will also come packaged with other immune supportive nutrients such as vitamin C.

These nutrients will in turn help your immune system to defend you against whatever viruses are going around. An Apple a Day…. How Quercetin Supports the Immune System by Emily Fawell and Lisa Patient Jan 31, Health Issues , Healthy Foods.

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So why is it so useful for our immune system? Quercetin supports immunity via various mechanisms. Firstly, it is an antioxidant. This is useful because infections result in oxidative stress, which can damage body tissues and worsen symptoms.

In animal studies, quercetin proved to be a powerful antioxidant and reduced the oxidative stress caused by the flu virus and hence protected the lungs from damage. Chronic inflammation goes hand in hand with oxidative stress and can drive many chronic diseases — quercetin works as an anti-inflammatory.

Quercetin is often used therapeutically to help with symptoms of asthma, hay fever and allergic reactions. All these conditions involve histamine, which causes redness, swelling, and symptoms such as watery eyes and constricted airways. Quercetin inhibits the release of histamine from white blood cells and so reduces the reaction.

Consumption of apples a concentrated source of quercetin has been linked to a reduction of asthmatic symptoms in children. One study found that women who ate apples during pregnancy bore children with significantly lower rates of asthma and wheezing at 5 years old than the children of pregnant women who did not eat apples.

No associations were found with fruit and vegetables in general. This does not, of course, prove that quercetin was responsible for the reduction in symptoms, but it is an interesting finding. Quercetin has, however, been studied in more depth as an isolated compound in animals.

In one rodent study, anaphylactic reactions to peanuts were completely resolved after 4 weeks of being fed quercetin daily. Note that there is no comparable evidence in humans yet, so please do not start experimenting if you or someone close to you has a peanut allergy.

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