What Are Flavonoids?
Flavonoids are plant compounds with a variety of health benefits. Many plant-based foods, as well as beverages such as tea and wine, contain flavonoids.
Many studies have shown the benefits of these plant chemicals (phytonutrients). Researchers suggest that a diet rich in flavonoids could reduce your risk for cardiovascular disease, diabetes, and some types of cancer.
You might also hear about flavonoids called vitamin P, bioflavonoids, or polyphenols. Plants use these compounds for their own growth. They help plants attract pollinators and fight infections. They also give some fruits and vegetables their deep, rich colors.
Types of Flavonoids
There are six main classes of flavonoids:
Flavonols. The most studied flavonols are quercetin, myricetin, and fisetin. Flavonols are linked to many health benefits, including a lower risk of heart disease. They’re found in:
- Lettuce
- Tomatoes
- Onions
- Kale
- Apples
- Grapes
- Berries
- Tea
- Red wine
Isoflavones. These compounds are found mostly in legumes and soybeans and, less commonly, in other plants. Some are considered to be phytoestrogens, a form of estrogen that we can get from food.
Flavanones. Citrus fruits like oranges, lemons, and grapefruits have flavanones. These compounds make citrus juice and peels taste bitter. They help:
- Lower inflammation
- Act as antioxidants
- Lower cholesterol
- Lower fat levels in your blood
Flavanols. Flavanols are also called flavan-3-ols or catechins. Black tea, oolong tea, and chocolate are rich in catechins. They’re also found in fruits, including:
- Bananas
- Blueberries
- Peaches
- Apples
- Pears
Anthocyanins. The color of red, purple, and blue fruits comes from anthocyanins. They're found in:
- Red grapes
- Cranberries
- Raspberries
- Strawberries
- Blueberries
- Bilberries
- Blackberries
Chalcones. These are thought to have antioxidant properties. Some types of these compounds are used in beauty products. Foods high in chalcones include:
- Tomatoes
- Pears
- Strawberries
- Bearberries
- Wheat
Health Benefits of Flavonoids
Experts are still studying how flavonoids affect health. But some of the potential benefits include:
Antioxidant effects. Your body makes free radicals, unstable molecules that can damage cells. This damage can lead to inflammation and contribute to other problems such as cancer and heart disease.
Antioxidants help neutralize free radicals. Flavonoids have been shown to have antioxidant effects. They might help prevent chronic diseases, but your body may not absorb them as well as other antioxidants like vitamin C.
Heart disease prevention. Flavonoids might reduce your risk for heart disease. Their antioxidant activity could help lower inflammation and blood pressure.
Diabetes prevention. Flavonoids may reduce your risk for type 2 diabetes because they improve how your body uses glucose (sugar) and digests carbohydrates. A study of 200,000 people showed that those who consumed lots of flavonoids had a lower risk of diabetes.
Brain health. Flavonoids might protect your brain by lowering inflammation and protecting your vascular (blood vessel) system. Studies show a type of flavonoids found in cocoa could improve brain function, memory, and blood flow.
Cancer prevention. A long-term review of several studies found that a diet rich in flavonoids leads to a reduced risk of breast, prostate, and colorectal cancers. The studies suggest that different flavonoids help protect against specific types of cancer. For example, anthocyanidins decrease lung cancer risk, while flavonols reduce the risk of prostate cancer. That's why it’s best to consume a variety of plant foods.
Managing chronic pain and inflammation. Another review study looked at flavonoids' anti-inflammatory and pain-relieving properties. Flavonoids were found to reduce cells' response to pain. Researchers propose that flavonoids could someday be used to manage chronic pain and treat inflammatory diseases.
Treating viral infections. Flavonoids have known antibacterial and antiviral effects. Many lab studies show that certain flavonoids can help keep the H1N1 flu, HIV, SARS, and RSV viruses from reproducing themselves. But we need more research to figure out how flavonoids might work in the body against viruses.
Foods With the Most Flavonoids
You can buy many flavonoid supplements. But, as with most nutrients, it’s probably best to get them from food. These 10 foods are some of the best sources of dietary flavonoids:
- Berries
All berries contain flavonoids, but some varieties are more potent than others. Blackberries are particularly powerful and include all six types of flavonoids. Blueberries, cherries, and raspberries also contain all flavonoids. Strawberries have moderate amounts of anthocyanidins. - Red cabbage
Another great source of anthocyanidins is red cabbage. Anthocyanidins have been studied for their protective effects against cancer, cardiovascular disease, diabetes, and age-related thinking disorders. - Onions
Onions are the basis of many different cuisines, and it’s no wonder why. This humble vegetable is a powerhouse of nutrients and adds flavor to any dish. Onions are a great source of flavonols, which can reduce the risk of prostate cancer. - Kale
This leafy green is another great source of flavonols. Kale leaves make an excellent base for salads. You can also add them to soups and stews to boost their nutritional value. If you don’t care for the taste, add kale to smoothies and protein shakes. - Parsley
Parsley provides more flavonols in the American diet than any other food. It contains over 130 milligrams of flavonols per gram. Add it to soups and sauces, or sprinkle over dishes before serving. - Tea
One of the easiest ways to add flavonoids to your diet is to drink tea. Green, oolong, and black teas all contain high levels of flavanols, which have been studied for their benefits to heart and brain health. - Red wine
Another good source of flavanols is red wine. Red wine in moderation has many health benefits and may help lower your risk for cardiovascular disease. - Dark chocolate
Chocolate and cocoa are both high in flavanols. Cocoa, in particular, has been studied for its brain-boosting properties and its protective effect on the cardiovascular system. - Citrus fruits
Citrus fruits such as oranges, grapefruit, tangerines, lemons, and limes contain flavanones. Juicing these fruits gives you a more concentrated source of these healthy plant compounds. Try squeezing fresh lemon or lime juice into ice water to add nutritional value. - Soybeans
Soybeans come in many forms and are a top source of isoflavones. Edamame, tofu, and tempeh can boost the isoflavones in your diet. Isoflavones are thought to help protect against reproductive cancers such as breast, ovarian, prostate, and testicular cancers.
