Introduction to Flavonoids

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Flavonoids are plant compounds that may play important roles in health promotion and disease risk reduction.  Read on to learn more!

What are flavonoids?

Flavonoids are compounds found naturally in various plants that have antioxidant and anti-inflammatory properties and have been associated with various health benefits.

While over 5000 plant compounds have been identified as part of the large flavonoid family; these compounds are classified among different flavonoid subclasses, based on chemical structures.

There are six major subclasses of flavonoids that are of dietary importance including: anthocyanidins, flavan-3-ols, flavanones, flavones, flavonols, and isoflavones.  Some foods contain only one subclass, while others contain several. 

See the chart below for an overview of the major flavonoid subclasses and the associated common food sources.

What foods have flavonoids?

Flavonoid subclassCommon food sources
AnthocyanidinsBerries (red, blue, and purple), red grapes, red wine
Flavan-3-olsTeas (white, green, oolong), cocoa-based products, grapes, berries, apples
FlavanonesCitrus fruit (oranges, grapefruits, lemons)
FlavonesParsley, thyme, celery, hot peppers
FlavonolsOnions, kale, broccoli, apples, berries, teas
IsoflavonesSoybeans, soy foods, legumes

Health benefits of flavonoids

There has been much interest in flavonoids as a flavonoid-rich diet has been associated with many health benefits such as a lower risk of:

  • heart disease
  • high blood pressure
  • type 2 diabetes
  • some cancers
  • cognitive decline

Researchers are still studying exactly how flavonoids may affect health.  One of the ways flavonoids are thought to exert their health benefits are through their powerful antioxidant properties.  Flavonoids may help prevent damage to the body caused by free radicals, which harm cells and over time has been linked with many chronic diseases and memory decline.

Flavonoids may also help control cellular activity and have been shown to play a role in activities related to the prevention of cardiovascular disease, such as reducing inflammation, relaxing blood vessels and inhibiting blood clots.

Further, flavonoids have shown anti-diabetic properties such as improving insulin secretion and increasing glucose (sugar) uptake by cells.

A lot of research has been done investigating flavonoids and while there is accumulating evidence linking a flavonoid-rich diet with many potential health benefits, more research is needed to prove and solidify the findings.

How much do I need?

While a dietary reference intake (DRI) has not been established for flavonoids, following Health Canada’s Food Guide recommendations to include plenty of vegetables and fruits in your meals and snacks; try making half of your plate vegetables and fruits; and try to choose protein foods that come from plants every day would be good ways to help add a variety of different flavonoids to your diet.  

Bottom line

  • A flavonoid-rich diet may offer several health benefits.  While there is accumulating evidence linking a flavonoid-rich diet with many potential health benefits, more research is needed to solidify the findings.  
  • Common flavonoid food sources such as fruits and vegetables are easy to incorporate into your diet and also offer excellent sources of other important nutrients for good health, such as vitamins, minerals and fibre.   
  • Remember to eat a variety of healthy foods each day. See Canada’s Food Guide for more information:

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