Flavonoids—Once Called Vitamin P—May Help Slow Signs of Aging, But They’re Not Actually Vitamins
Flavonoids, also once referred to as “Vitamin P,” are plant compounds that your body can’t make on its own but may provide important health benefits if consumed regularly through diet. While you won’t find Vitamin P on any list of essential vitamins anymore—because it was removed from the category decades ago—scientific interest in flavonoids hasn’t gone away. In fact, recent research continues to explore their antioxidant properties and potential to reduce disease risk.
Let’s be clear from the beginning: flavonoids are not officially vitamins. But that doesn’t mean they’re useless. That misunderstanding started in the early 20th century when scientists observed certain plant compounds helping reduce capillary fragility. They thought it was a newly discovered vitamin and called it Vitamin P. Later, they realized that these were flavonoids, a group of polyphenolic compounds present in nearly all fruits and vegetables.
What Flavonoids Actually Are
Flavonoids are naturally occurring compounds found mostly in plant-based foods. They’re part of a larger group called polyphenols. You can find them in colorful fruits, vegetables, herbs, teas, and oils—especially citrus peels, leafy greens, green tea, and foods like soy or olives. Flavonoids have antioxidant and anti-inflammatory properties. That means they help fight oxidative stress in the body, which is a fancy way of saying they may reduce damage caused by free radicals—unstable molecules that age your cells faster.
Now, does this mean flavonoids are magic? No. But they’re not fluff either. They actually help your body handle the wear and tear that comes with aging, metabolic processes, and environmental exposures like pollution or poor diet.
They’re broken down into subcategories like flavonols, flavanones, isoflavones, and more. Each one has different roles and is found in different foods. For example, isoflavones are found mostly in soy and have been studied for hormonal effects, while flavonols like quercetin are abundant in apples and onions.
Why People Thought They Were Vitamins
The confusion goes back to when these compounds were first isolated. Scientists noticed that people eating diets rich in plant-based foods had fewer issues with fragile blood vessels and internal bleeding. They extracted some of these plant chemicals, saw promising results, and assumed they had discovered a new vitamin that supported vascular health. It was given the temporary name “Vitamin P,” with the “P” standing for permeability, referring to blood vessel walls.
Eventually, deeper studies revealed that these substances didn’t meet the strict biochemical criteria to be considered vitamins. Unlike Vitamin C or B12, flavonoids are not essential in the way that deficiency causes specific diseases. So, “Vitamin P” was dropped, but flavonoids stuck around as a research subject.
What They Actually Do in the Body
Flavonoids don’t function like vitamins. You won’t get scurvy or night blindness from not eating them. But that doesn’t mean they’re irrelevant. Flavonoids can influence several biological pathways, especially those related to inflammation, oxidative stress, and metabolic regulation.
Multiple studies suggest flavonoids can help reduce the risk of certain chronic conditions—heart disease, type 2 diabetes, high blood pressure, and even some forms of cancer. These are not cure-all claims, and most of the research is observational or animal-based. Still, the patterns are consistent: people who eat more fruits and vegetables rich in flavonoids tend to have better long-term health outcomes.
There’s also evidence that flavonoids can contribute to skin health by protecting collagen and reducing inflammation. Some dermatology researchers have proposed that dietary intake of flavonoids might help slow skin aging, but again, this is correlation—not direct causation.
Common Sources of Flavonoids
Flavonoids are abundant in many everyday foods, especially ones that are colorful, bitter, or aromatic. Here are some notable sources:
- Citrus fruits (especially the peels)
- Berries (blueberries, blackberries, strawberries)
- Red grapes
- Apples (especially with skins)
- Onions
- Leafy greens like spinach
- Green tea and black tea
- Soy and soy-based foods (tofu, tempeh)
- Olive oil
- Dark chocolate
- Fresh herbs like mint and parsley
One important note: the way you prepare these foods matters. For example, peeling fruits removes some of the highest concentrations of flavonoids. Boiling vegetables in water can cause flavonoids to leach out into the water. Using minimal cooking or steaming is a better method if preserving antioxidants is the goal.
Do Flavonoids Absorb Well?
That’s still being studied. Unlike vitamins with clear absorption rates and mechanisms, flavonoids are less predictable. Some are absorbed easily in the small intestine, while others reach the large intestine and are broken down by gut bacteria. The form in which flavonoids are consumed (raw vs. cooked, whole fruit vs. juice) also affects absorption.
Also, bioavailability is a factor. Just because you consume something doesn’t mean your body can use it efficiently. Flavonoids often undergo changes during digestion that can impact how useful they are by the time they reach your bloodstream.
Still, many researchers argue that you don’t need to worry too much about individual absorption rates. The bigger picture is that people who consume flavonoid-rich diets over time tend to see health benefits, regardless of the exact absorption details.
What Happens If You Don’t Get Enough?
Again, flavonoids aren’t essential nutrients like Vitamin D or Iron. There’s no defined deficiency state for them. You won’t experience a crisis if you go a few days without them. But skipping them regularly—by not eating fruits and vegetables, drinking mostly sugar-laden beverages, and relying on ultra-processed foods—could mean you miss out on the long-term benefits they offer.
Over time, diets low in plant compounds may increase the risk of inflammation, oxidative stress, and metabolic diseases. You may not notice the damage immediately, but it builds up. Many chronic diseases don’t happen overnight—they result from years of cumulative impact.
Flavonoids vs. Supplements
There are flavonoid supplements on the market. Some contain isolated compounds like quercetin or catechins from green tea. But most health experts agree: it’s better to get flavonoids from whole foods.
That’s because whole foods contain a combination of nutrients—fiber, water, vitamins, and minerals—that work together in ways supplements often can’t replicate. Also, dosages in supplements vary wildly and are not tightly regulated. Some supplements may even interfere with medications or have side effects at high doses.
Eating a bowl of berries or sipping green tea is safer, more balanced, and harder to overdo.
Conclusion: Not a Vitamin, Still Worth Eating
Flavonoids might have lost their “Vitamin P” label a long time ago, but they haven’t lost their potential. While they’re not essential nutrients in the technical sense, research continues to suggest they support long-term health, especially when part of a diet rich in colorful, plant-based foods.
You don’t need to memorize every subtype or track milligrams. Just eat a wide variety of fruits, vegetables, herbs, and teas regularly. That’s how you get these compounds into your system in a way your body understands. And while they won’t stop time, they just might help slow down the parts of aging that matter most—like cellular damage, inflammation, and chronic disease risk.
