What are Flavonoids and Why Do You Need Them in Your Diet?

Flavonoids are natural compounds found in plant foods. They are classified under phytochemicals and are one of the most studied groups of phytonutrients. All plants produce phytochemicals, however, dietary flavonoids are found in edible plant foods such as herbs, spices, fruits, and vegetables. They often act as antioxidants, anti-cancer, or anti-inflammatory in the body, thus providing various health benefits. 

Types of Flavonoids

Flavonoids are classified into different types based on how they interact with the body.  Their food sources also vary. Below are the 5 classes of flavonoids. 

Flavanols and Flavan-3-ols

Flavanols, also referred to as flavan-3-ols are the largest subgroups of flavonoids. They are found in a wide range of foods and are well-known for their antioxidant properties. Some fruits and vegetables that contain flavonoids include berries, kale, grapes, onions, garlic, and broccoli. For example, alliums like garlic, scallions, and onions contain a flavonol known as quercetin. Other plant compounds classified under flavanols include myricetin, kaempferol, and fisetin. 


Flavanones are predominantly found in citrus fruits and are known for their anti-inflammatory properties. Some of their health benefits include fighting free radicals, and weight and cholesterol level management. Some examples of flavanones include diosmin, hesperidin, eriodictyol, and naringenin. They are found in grapefruits, lemons, oranges, and limes. 


Isoflavones have hormone-balancing properties and can also help fight diseases. Some isoflavones act as estrogens in some animals, hence they are referred to as phytoestrogens. They are mainly found in legumes and beans, however, they have been detected in some fermented foods. 


Flavones give flowering plants their cream or while and blue color. Their primary function is to protect plants from ultraviolet light and help ward off harmful insects. When they are consumed by humans, they provide anti-inflammatory properties. Some food sources of flavones include chamomile, parsley, green olives, and red peppers.


Anthocyanins are pigments produced by plants, fruits, and flowers. They are found in the skin of fruits like blueberries, strawberries, red and purple grapes, and blackcurrants. Anthocyanins are some of the most beneficial plant compounds. They have anti-inflammatory, anti-cancer, antimicrobial, and antidiabetic effects. Common types of anthocyanin in plants include malvidin, cyanidin, petunidin, delphinidin, and pelargonidin.

Why Do You Need Flavonoids in Your Diet?

Depending on how they are broken down, flavonoids have properties that can help prevent diseases and stimulate the immune system. These properties work by reducing inflammation, preventing oxidative stress, and fighting cancer cells. Here are some of the reasons you need a diet rich in flavonoids.

Blood Pressure Regulation

High blood pressure is a threat to cardiovascular health. Hence, any compound that regulates blood pressure is good for the heart. Certain dietary flavonoids found in fruits like cocoa, apples, citrus fruits, and berries are known to lower blood pressure in hypertensive people. The antioxidant properties in these foods help to expand blood vessels, ultimately enhancing the flow of oxygen and blood to the heart and preventing heart diseases. 

The antioxidant effects in flavonoids can reduce bad cholesterol also known as low-density lipoprotein (LDL) which builds up in the blood vessels and constricts blood flow. This can also lower the risk of cardiovascular diseases.

Cancer Prevention

Flavonoids have been proven to wield anti-cancer effects. For example kaempferol, a compound found in foods like onions, broccoli, spinach, and squash is effective in mitigating ovarian cancer cell growth. The anticancer properties of this flavonoid can hunt free radicals, reduce oxidative stress, repair DNA and prevent harmful substances from being metabolized and transformed into carcinogenic chemicals. Eating fruits rich in flavonoids can reduce your chances of developing certain cancers.

Lowered Risk of Getting Type 2 Diabetes

Type 2 diabetes results from impaired insulin secretion, and increased resistance to insulin. Some types of flavonoids have been found to regulate how carbohydrates are broken down, improve lipid profile and regulate the enzymes and hormones in the body. The positive effect of this is a reduced risk of diabetes, obesity, and other similar complications. Quercetin present in garlic and citrus fruits can lower blood sugar and prevent type 2 diabetes.

Pain Alleviation and Stress Reduction

Studies suggest flavonoids can effectively manage pain and inflammation. Thanks to their anti-inflammatory effects, flavonoids can reduce pathological pain that occurs after inflammation or peripheral nerve injury. Certain studies have also explored the possible pain reduction effects of hesperidin (found in citrus fruits) and naringenin (found in cacao, tart cherries, and tomatoes). Both of these flavonoids were found to target channels expressed by neurons and immune cell signaling pathways to reduce pain and inflammation.

Improved Brain Function

The anti-inflammatory properties found in certain flavonoids are also beneficial to cognitive health. By helping to reduce neuroinflammation and oxidative stress, researchers believe flavonoids can help prevent damage to brain cells and reverse symptoms related to Alzheimer’s disease. Flavonoids can also enhance brain function and reduce cognitive decline.

Viral Infection Treatment

Naturally occurring dietary flavonoids such as quercetin, naringin, hesperetin, and catechin have been found to have antiviral effects. These compounds inhibit virus replication and infectivity, thereby protecting the body against viral infection. 

The Bottom Line

Flavonoids are abundant in fresh plant foods such as whole grains, legumes, fruits, vegetables, herbs, and spices. They are rich in antioxidants, anti-inflammatory, anti-cancer, anti-viral, and anti-allergic activities. Dietary flavonoids can prevent the development of diseases like cancer, type 2 diabetes, Alzheimer's disease, and cardiovascular diseases. Eating fruits and vegetables with a rich palette of colors is a great way to increase your intake of flavonoids.