Vitamin P is a term that was once used for a group of plant compounds called flavonoids. However, these compounds are not actually vitamins.

There are several types of flavonoids found in fruits, vegetables, tea, cocoa, and wine. They give certain foods their color, provide plants with protection from ultraviolet (UV) rays and infection, and may offer health benefits (1).

This article provides an overview of vitamin P, including info on the different categories of flavonoids, food sources, and possible benefits.

Flavonoids, also known as bioflavonoids, are a family of polyphenol plant compounds with six subclasses. There are currently over 6,000 known flavonoids (2).

When first extracted from an orange by scientists in 1930, they were thought to be a new type of vitamin and, therefore, named vitamin P. This name is no longer used, as flavonoids are not vitamins (1).

Flavonoids exist in plants to help prevent infection, protect against the sun and environmental stresses, and attract insects for pollination. They’re also responsible for the color of many deep-colored fruits and vegetables, such as berries, cherries, and tomatoes (1).

Here are the major classes of flavonoids and their food sources:

  • Flavonols. The most abundant source of flavonoids in the diet, flavonols include kaempferol, quercetin, myricetin, and fisetin. These compounds are found in olive oil, berries, onions, kale, grapes, tomatoes, red wine, and teas (1, 2).
  • Flavones. These are also widely present in the food supply. They exist in parsley, thyme, mint, celery, and chamomile (2).
  • Flavanols and flavan-3-ols. This subclass includes catechins, such as epicatechin and epigallocatechin, which are found in high concentrations in black, green, and oolong tea. Flavanols are also present in cocoa, apples, grapes, and red wines (1).
  • Flavanones. Found in citrus fruits, flavanones are responsible for the bitter taste of orange, lemon, and other citrus peels. Examples include hesperitin, naringenin, and eriodictyol (2).
  • Isoflavones. The best-known isoflavones are genistin and daidzin, which are found in soybeans and soy products (1).
  • Anthocyanidins. Most red, blue, or purple fruits and vegetables get their color from anthocyanidins. Compounds like cyanidin, delphinidin, and peonidin are present in cranberries, strawberries, blueberries, blackberries, grapes, and red wine (1).

The major classes of flavonoids include flavonols, flavones, flavanols, flavanones, isoflavones, and anthocyanidins. Different types of flavonoids are abundant in fruits, vegetables, red wine, cocoa, and teas.

Flavonoids are thought to offer a variety of health benefits and help prevent heart disease, diabetes, and other diseases.

Perhaps the best-studied function of flavonoids is their ability to act as antioxidants. They have been shown to reduce the formation of reactive molecules called free radicals, which can lead to cell damage and disease (1, 3).

Test-tube vs. human studies

Most research on the benefits of flavonoids has been conducted in test tubes. Thus, the activity of flavonoids in the body is not well understood.

In fact, it’s generally thought that they’re poorly absorbed and not very bioavailable.

For one, it appears that your metabolism largely influences the bioavailability of flavonoids in your body. They may also be rapidly excreted (4, 5).

When flavonoids are consumed, they’re broken down into compounds called metabolites. Some of these metabolites may exhibit properties similar to those of the flavonoid from which they were derived, but others do not (4, 5).

What’s more, studies suggest that whether flavonoids are consumed with carbs, proteins, or fats can affect their bioavailability and absorption. These factors are also affected by the composition of your gut bacteria (6, 7).

Thus, it’s difficult to determine how and whether a particular flavonoid affects human health.

Possible health benefits

While limitations exist, some human studies suggest that flavonoids have possible health benefits.

Below are some of those benefits, many of which stem from their antioxidant activity, as well as other mechanisms that are not fully understood:

  • Brain health. Several studies on cocoa flavanols suggest that they may protect brain cells and boost brain health in humans, likely via interactions with cell signaling pathways involved in cell survival and memory (8).
  • Diabetes. One review found high dietary intake of specific flavonoids was associated with a lower risk of type 2 diabetes. For every 300 mg of flavonoids consumed daily, the risk of diabetes decreased by 5% (9).
  • Heart disease. A review of 14 studies in humans showed the intake of certain classes of flavonoids, specifically flavonols, anthocyanidins, proanthocyanidins, flavones, flavanones, and flavan-3-ols, was associated with a significantly lower risk of heart disease (10).

While results from some observational studies suggest that flavonoids may help protect against disease, more extensive research is needed to fully understand how flavonoids affect human health.

Furthermore, this article highlights just a few of the possible health benefits of flavonoids. A growing body of research is examining the functions of flavonoids, as well as the specific classes of flavonoids.


Flavonoids are thought to offer a number of health benefits, but most research has been conducted in test tubes. Some observational studies in humans suggest that they may boost brain health and decrease the risk of heart disease and diabetes.

Currently, there is no Dietary Reference Intake (DRI) for flavonoids, as they’re not considered essential for human development. A diet rich in healthy, whole foods will naturally contain flavonoids and contribute to good health (11).

Therefore, supplemental versions are unnecessary, but they do exist. Some of the most common flavonoid supplements include quercetin, flavonoid complexes, and rutin (12).

There’s no standardized dosage for flavonoid supplements, and each kind may have specific instructions for its use. The side effects and potential dangers of many of these supplements are unknown.

Experts warn that while there’s no risk of toxicity from the amount of flavonoids commonly consumed through food, there may be risks associated with high dose supplements (11).

High doses of flavonoids may negatively affect thyroid function, interact with medications, and affect levels of other nutrients in your body (12).

What’s more, supplements are not tightly regulated by the Food and Drug Administration (FDA) and, therefore, can be contaminated or contain amounts of flavonoids that differ from what’s reported on their labels.

Finally, many research studies have shown that eating whole foods that contain certain nutrients offer greater benefits than their supplement-form counterparts.

If you want to try a supplement, consult your healthcare provider, especially if you’re pregnant or breastfeeding.


Flavonoids are widely available in foods, but supplements are available. These supplements are not regulated and may have unknown harmful side effects. Always consult a healthcare provider before trying one.

Flavonoids, once known as vitamin P, are a large class of plant compounds found in deeply colored fruits, vegetables, cocoa, tea, and wine.

Studies suggest that they act as antioxidants and may help protect against chronic diseases. However, the beneficial effects of flavonoids in the human body may be limited by metabolism and other factors.

To reap the possible benefits of flavonoids, eat a variety of plant foods. Supplements are also available, but they should only be taken after consulting a healthcare provider, as their effects are not well understood.

Eating a variety of whole foods that are good sources of flavonoids is likely more beneficial to your overall health.