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What are flavonoids and what is their effect?

Published: 25/04/2022
Katarzyna Kieszkowska
She holistically guides clients and creates educational programs. She continues to expand her knowledge of nutritional medicine, food therapy, natural approaches to health and lifestyle. She is passionate about a healthy lifestyle.

Date of the last update: 25.04.2022

Flavonoids have become an area of growing interest over the recent months. No wonder – owing to their biological activity they can be used to cure certain diseases. They also have health-promoting properties – they scavenge free radicals, regulate steroid hormone metabolism and inhibit cancer cell proliferation. Increasing awareness about flavonoids present in fruits and vegetables is a big step to convincing more people of their beneficial influence on human health and the proper body function. So what are flavonoids? Where to find them and what effect do they have? Read our article to find out!

Table of Contents:

  1. What are flavonoids?
  2. Flavonoids – where to find them?
  3. Flavonoids – effects
  4. Summary

You can read this article in 3 minutes.

What are flavonoids?

Flavonoids are various compounds naturally occurring in plants. You could say they are plant equivalents of the human immune system, and not without reason. Thanks to them, plants can fight different intruders – bacteria, fungi and insects. In addition to their protective properties, flavonoids are responsible for colours, ranging from light and warm to dark and cold. This is why oranges are orange and peas are green. Flavonoids affect flavour and smell. Most of them, however, have an unpleasant bitter taste. These compounds are found in every part of the plant, especially under the skin (as in fruit). The amount also depends on how ripe the fruit is. The more sun the fruit receives, the more flavonoids it contains. These natural plant compounds are divided into: flavins, isoflavones, flavanols and anthocyanins.

Flavonoids – where to find them?

As mentioned above, flavonoids are found in plants, fruits and some herbs. It is worth mentioning that the reference daily intake of flavonoids is 1g–2g. But these substances do not accumulate in the body, so you need to supply a certain amount of flavonoids every day. The daily dose of these compounds may, of course, increase when you: 

  • drink a lot of water,
  • smoke cigarettes,
  • abuse alcohol,
  • have a weak immune system,
  • have a poor diet.

Deficiency in flavonoids can lead to an increased tendency to burst capillaries and dilated capillaries on the face and legs (bruises under the eyes, skin bleeding).

Rich dietary sources of flavonoids include:

  1. pomegranate and red coloured fruits – blueberries, blackcurrants, blueberries, red grapes, elderberries, strawberries,
  2. pulses – peas, beans,
  3. coffee and tea – especially black and green tea,
  4. red wine and grape juice,
  5. nuts, buckwheat, spices and herbs such as rosemary,
  6. citrus fruits – lemon, orange, grapefruit,
  7. other fruits such as rosehip, peach, apple

So remember to consume adequate amounts of fruit and vegetables. Apart from flavonoids, they also contain other vitamins and antioxidants which are certainly useful for the proper body function. By regularly eating fresh fruit and vegetables you reduce the risk of diseases of civilisation.

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Flavonoids – effects

Estimates say that at least half of the flavonoids pass from the gastrointestinal tract into the blood in an unchanged form, while the remaining ones are mainly metabolised in the liver and intestines. Flavonoids as antioxidants can act in a direct manner by:

  • capturing and scavenging free radicals 

And indirectly, by:

  • reducing the formation of free radicals,
  • inhibiting enzymes responsible for the formation of free radicals,
  • protecting other antioxidants.

In addition, flavonoids:

  • support cardiovascular health – they maintain normal blood pressure, have a beneficial effect on the condition of blood vessel walls, influence the proper heart health and function, reduce cholesterol levels,
  • reduce the number of erythrocytes (red blood cells),
  • protect vitamin C in the body by increasing its absorption from the gastrointestinal tract, supporting its assimilation by the body and inhibiting ascorbic acid oxidase,
  • remove toxic elements from the body – they can form complexes with heavy metals, thus accelerating and facilitating toxin removal,
  • help in cleansing the urinary tract,
  • slow down the ageing process,
  • have a positive effect on human eyesight – anthocyanins are responsible for this, as among other things, they improve visual acuity at night and speed up the visual pigment regeneration process,
  • they have estrogenic effects – reduce hot flashes, improve skin condition and help with mood swings,
  • sustain the effects of adrenaline.

Explore more: How Do Probiotics and Prebiotics Work?


Flavonoids are compounds which, despite everything, are difficult to avoid. Their presence in fruit and vegetables makes us consume them every day. However, there is no reason to worry, as they provide so many pro-health effects for our organism! But remember that everything is best in moderation – their excessive doses can probably reduce the bioavailability of some elements, folic acid and vitamins, as well as block or reduce the effect of antibiotics.

Katarzyna Kieszkowska
She holistically guides clients and creates educational programs. She continues to expand her knowledge of nutritional medicine, food therapy, natural approaches to health and lifestyle. She is passionate about a healthy lifestyle.