什麼是槲皮素?好處、食物、劑量和副作用

Quercetin is a natural pigment found in many:

  • fruit
  • vegetable
  • cereals

It is one of the most abundant antioxidants in the diet and plays an important role in helping your body fight free radical damage related to chronic diseases.

In addition, its antioxidant properties may help reduce:

  • inflammation
  • Allergy symptoms
  • blood pressure

This article explores the properties of quercetin:

  • use
  • benefit
  • side effect
  • dose

What is quercetin?

Quercetin is a pigment that belongs to a group of plant compounds called flavonoids.

Flavonoids are found in:

  • vegetable
  • fruit
  • cereals
  • Tea
  • wine

They are associated with a variety of health benefits, including reducing the risk of heart disease, cancer, and degenerative brain diseases.

The beneficial effects of flavonoids such as quercetin come from their role in the body.

Antioxidants are compounds that can bind and neutralize free radicals.

Free radicals are unstable molecules, and when their levels are too high, they may cause cell damage.

The damage caused by free radicals is related to many chronic diseases, including cancer, heart disease and diabetes.

Quercetin is the most abundant flavonoid in the diet. It is estimated that the average person consumes 10-100 mg per day through various food sources.

Foods that usually contain quercetin include onions, apples, grapes, berries, broccoli, citrus fruits, cherries, green tea, coffee, red wine, and capers.

It can also be used as a dietary supplement in powder and capsule form.

People take this supplement for several reasons, including:

  • Improve immunity
  • Fight inflammation
  • Fight allergies
  • Auxiliary sports performance
  • Maintain overall health

Health benefits of quercetin

Research has linked the antioxidant properties of quercetin to various potential health benefits.

Here are some of its main benefits based on science.

Can reduce inflammation

Free radicals may not only damage your cells.

Studies have shown that high levels of free radicals may help activate genes that promote inflammation. Therefore, high levels of free radicals may lead to increased inflammation.

Although a little bit of inflammation is needed to help your body heal and fight infections, persistent inflammation is related to health problems, including certain cancers, and heart and kidney diseases.

Research shows that quercetin may be.

In test-tube studies, quercetin reduced inflammatory markers in human cells, including tumor necrosis factor alpha (TNFα) and interleukin 6 (IL-6) molecules.

An 8-week study of 50 women with rheumatoid arthritis observed that participants who took 500 mg of quercetin experienced a significant reduction in morning stiffness, morning pain, and pain after exercise. .

Compared with those who received a placebo, their inflammatory markers (such as TNFα) were also reduced.

Although these findings are promising, more human studies are needed to understand the compound's potential anti-inflammatory properties.

Can relieve allergy symptoms

The potential anti-inflammatory properties of quercetin can relieve allergy symptoms.

Test tube and animal studies have found that it may block enzymes related to inflammation and inhibit chemicals that promote inflammation, such as histamine.

For example, one study showed that taking quercetin supplements can suppress peanut-related allergic reactions in mice.

Nevertheless, it is not yet clear whether the compound has the same effect on human allergies, so more research is needed before it can be recommended as an alternative therapy.

May have anti-cancer effects

Because quercetin has antioxidant properties, it may have anti-cancer properties.

In a review of test tube and animal studies, it was found that quercetin can inhibit the cell growth of prostate cancer cells and induce cell death.

Other test tube and animal studies have observed that the compound has similar effects on liver, lung, breast, bladder, blood, colon, ovarian, lymph and adrenal cancer cells.

Although these findings are promising, human studies are needed before quercetin can be recommended as an alternative therapy for cancer.

May reduce your risk of chronic brain disease

Studies have shown that the antioxidant properties of quercetin may help prevent degenerative brain diseases such as Alzheimer's disease and dementia. .

In one study, mice with Alzheimer's disease received quercetin injections every 2 days for 3 months.

By the end of the study, the injection reversed several markers of Alzheimer's disease, and the mice performed better on the learning test. .

In another study, a diet rich in quercetin reduced Alzheimer's disease markers and improved brain function in mice in the middle and early stages of the disease.

However, this diet has little effect on animals suffering from advanced Alzheimer's disease.

Coffee is a popular beverage and is associated with reducing the risk of Alzheimer's disease.

In fact, studies have shown that quercetin, not caffeine, is the main compound in coffee, and it has a potential protective effect on this disease.

Although these findings are promising, more research on humans is needed.

May lower blood pressure

High blood pressure affects one-third of American adults. It increases your risk of heart disease-this is the leading cause of death in the United States.

Studies have shown that quercetin may help lower blood pressure levels. In test-tube studies, the compound appeared to have a relaxing effect on blood vessels.

When hypertensive mice took quercetin daily for 5 weeks, their systolic blood pressure and diastolic blood pressure (upper and lower limit) decreased by an average of 18% and 23%, respectively.

Similarly, a review of 9 human studies of 580 people found that taking more than 500 mg of quercetin supplements per day reduced systolic and diastolic blood pressure by an average of 5.8 mm Hg and 2.6 mm Hg, respectively.

Although these findings are promising, more human studies are needed to determine whether the compound can be an alternative treatment for hypertension.

Other potential benefits

Here are several other potential benefits of quercetin:

  • May help fight aging. Test tube and animal studies have shown that quercetin may help restore or eliminate senescent cells and reduce aging markers. However, more human research is needed.
  • May help exercise performance. A review of the 11-person study found that taking quercetin may slightly improve endurance sports performance.
  • May help control blood sugar. Human and animal studies have shown that the compound can reduce fasting blood sugar levels and prevent diabetes complications.

Food sources and dosage

Quercetin is naturally present in many plant foods, especially in the outer layer or peel.

Good food sources include:

  • Capers
  • Chili - yellow and green
  • Onions-red and white
  • Shallots
  • Asparagus - cooked
  • Cherry
  • tomato
  • Red apple
  • Red grapes
  • broccoli
  • Kale
  • Red leaf lettuce
  • Berries-all types such as cranberries, blueberries and raspberries
  • Tea-green and black

Please note that the content of quercetin in food may depend on the growth conditions of the food.

For example, in one study, organic tomatoes appeared to contain 79% more quercetin than traditionally grown tomatoes.

However, other studies have pointed out that there are differences in the quercetin content of various tomatoes regardless of the cultivation method. There is no difference between traditionally or organically grown bell peppers.

Quercetin Supplements

You can buy quercetin as a dietary supplement online and in health food stores. It comes in many forms, including capsules and powders.

The typical dosage range is 500–1,000 mg per day.

The bioavailability of quercetin itself is very low, which means your body absorbs it poorly.

This is why supplements may contain other compounds, such as vitamin C or digestive enzymes such as bromelain, because they may increase absorption.

In addition, some studies have shown that quercetin has a synergistic effect when combined with other flavonoid supplements such as resveratrol, genistein, and catechins.

Safety and side effects

Quercetin is found in many fruits and vegetables and is safe to eat.

As a supplement, it seems to be generally safe with few side effects.

In some cases, taking more than 1,000 mg of quercetin per day may cause mild symptoms such as headache, stomach pain, or tingling sensation.

When consumed in food, quercetin is safe for pregnant and lactating women.

However, there is a lack of research on the safety of supplementing quercetin in pregnant and breastfeeding women, so if you are pregnant or breastfeeding, you should avoid taking quercetin.

As with any supplement, consult your healthcare provider before taking quercetin, as it can interact with certain medications, including antibiotics and blood pressure medications.

Generalize

Quercetin is the most abundant dietary flavonoid.

It is related to improving sports performance and reducing inflammation, blood pressure and blood sugar levels. In addition, it may have brain protection, anti-allergic and anti-cancer properties.

Although its benefits seem promising, more human research is needed.

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