Flavonoids are a class of polyphenolic secondary metabolites found in plants, and commonly consumed in the diets of humans.

Chemically, flavonoids have the general structure of a 15-carbon skeleton, which consists of two phenyl rings (A and B) and a heterocyclic ring (C, the ring containing the embedded oxygen).

Flavonoids can be classified into:

flavonoids or bioflavonoids, or 


The three flavonoid classes all ketone-containing compounds and as such, anthoxanthins.

Flavonoids are a type of antioxidant compounds found in many plant-based foods, such as fruits, vegetables, nuts, tea, and wine. 

There are over 6,000 known flavonoids, classified into several subgroups based on their chemical structures.

Flavonoids are known for their health-protective properties, including their ability to reduce inflammation, improve cardiovascular health, and potentially reduce the risk of certain cancers. 

Flavonoids are a group of natural compounds found in various fruits, vegetables, tea, and red wine.

They have many health benefits, including:

1. Antioxidant properties: Flavonoids are powerful antioxidants that help protect the body against free radicals, which can damage cells and cause illnesses like cancer and heart disease.

2. Anti-inflammatory effects: Some flavonoids have anti-inflammatory properties that can help reduce inflammation in the body, which is linked to many chronic diseases.

3. Cardiovascular benefits: Certain flavonoids, such as those found in red wine and dark chocolate, can help lower blood pressure and reduce the risk of heart disease and stroke.

4. Improved brain function: Some flavonoids have been shown to improve memory and cognitive function, which may help prevent age-related decline in brain function.

5. Protection against cancer: Several studies have found that flavonoids can help prevent the growth and spread of cancer cells, particularly in the breast, colon, lung, and prostate.

6. Skin health: Certain flavonoids, such as those found in green tea, can help protect the skin against UV damage and reduce the signs of aging.

Overall, a diet rich in flavonoids can promote overall health and reduce the risk of many chronic diseases.

Some specific flavonoids, such as quercetin and catechins, have also been shown to have antiviral and immune-boosting effects.

Good sources of flavonoids include berries, apples, citrus fruits, onions, broccoli, kale, chocolate, and red wine.

Flavonoids are a class of compounds that are found in many plants, including fruits, vegetables, grains, tea, and wine. 

They are known for their antioxidant and anti-inflammatory properties and can provide a range of health benefits.

There are many different types of flavonoids, including quercetin, catechins, and anthocyanins. 

Quercetin, which is found in onions, apples, and berries, has anti-inflammatory properties and may help reduce the risk of heart disease. 

Catechins, which are found in green tea, are known for their antioxidant properties and may help protect against cancer and heart disease. 

Anthocyanins, which are found in red and purple fruits like blueberries and cherries, also have antioxidant properties and may help reduce the risk of chronic diseases.

Consuming flavonoids as part of a healthy diet can help reduce the risk of chronic diseases such as heart disease, stroke, and cancer. 

It is best to get flavonoids from whole foods rather than supplements as the overall nutrient profile of whole foods is beneficial beyond just the flavonoid content.

Flavonoids are secondary metabolites synthesized mainly by plants. 

The general structure of flavonoids is a 15-carbon skeleton, containing 2 benzene rings connected by a 3-carbon linking chain: depicted as C6-C3-C6 compounds. 

Flavonoids can be classified into different groups, such as anthocyanidins, chalcones, flavonols, flavanones, flavan-3-ols, flavanonols, flavones, and isoflavonoids.

Favonoids can be found in plants in glycoside-bound and free aglycone forms. 

The free form is the most common flavone and flavonol form consumed in the diet.

Flavonoids are the most important plant pigments for flower coloration, producing yellow or red/blue pigmentation in petals designed to attract pollinator animals. 

In higher plants flavonoids are involved in UV filtration, symbiotic nitrogen fixation, floral pigmentation, chemical messengering, physiological regulation, and cell cycle inhibition.

Some flavonoids have inhibitory activity against organisms that cause plant diseases.

Over 5000 naturally occurring flavonoids have been characterized from various plants.: classified as 



Parsley is a source of flavones

Blueberries are a source of dietary anthocyanidins

A variety of flavonoids are found in citrus fruits, including grapefruit.

Flavonoids are the most common group of polyphenolic compounds in the human diet and are found ubiquitously in plants.

Flavonols, are also found ubiquitously, but in lesser quantities. 

The widespread distribution of flavonoids, their variety and their relatively low toxicity compared to other active plant compounds allows humans to ingest significant quantities in their diet.

Foods with a high flavonoid content include parsley, onions, blueberries and other berries, black tea, green tea and oolong tea, bananas, all citrus fruits, Ginkgo biloba, red wine, sea-buckthorns, buckwheat, and dark chocolate with a cocoa content of 70% or greater.

Parsley, both fresh and dried, contains flavones.

Blueberries are a dietary source of anthocyanidins.

Black tea is a rich source of dietary flavan-3-ols.

The citrus flavonoids are much less concentrated in the pulp than in the peels.

Flavonoids exist naturally in cocoa, but because they can be bitter, they are often removed from chocolate, even dark chocolate.

Peanut skin contains significant polyphenol content, including flavonoids.

In the United States NHANES survey, mean flavonoid intake was 190 mg/d in adults, with flavan-3-ols as the main contributor.

Flavan-3-ols makes up about 80% of flavonoids for USA adults: mainly from tea or cocoa in chocolate, while intake of other flavonoids was considerably lower.

The FDA has not approved any health claim for flavonoids or approved any flavonoids as prescription drugs.

Flavonoids are poorly absorbed, at less than 5%,and then are quickly metabolized into smaller fragments with unknown properties, and rapidly excreted.

Flavonoids have negligible antioxidant activity in the body, and the increase in antioxidant capacity of blood seen after consumption of flavonoid-rich foods is not caused directly by flavonoids, but by production of uric acid resulting from flavonoid depolymerization and excretion.

Microbial metabolism is a major contributor to the overall metabolism of dietary flavonoids.

There is no clinical evidence that dietary flavonoids affect any disorders of inflammation.  

There is little evidence to indicate that dietary flavonoids affect human cancer risk.

Np significant association has been found between flavan-3-ol intake and cardiovascular disease mortality.

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