Fisetin: Benefits, side effects, dosage and research

We know the drill – one cup of fruits and vegetables every day, for our health. But what actually makes them good for our bodies? 

Well, fruits and vegetables are rich in flavonoids. These are bioactive compounds that occur naturally in plant-based foods, from fruits to even wine and chocolate.

They induce antioxidant activity in your body to ward off toxins and help fight chronic health conditions.

Fisetin is one such flavonoid found in many fruits and vegetables, including apples, peppers, tomatoes and onions.

It might not be the most popular flavonoid out there, but it has been studied for its potential anti-inflammatory properties.

So what exactly is fisetin, and how does it benefit our personal health? Here’s everything you need to know about fisetin in relation to our bodies.

What is fisetin?

Fisetin is a flavonol – one of several types of flavonoids found in plants and plant-based foods. Flavonols are regarded for their antioxidant properties and may help manage symptoms of cardiovascular disease.

Some popular sources of flavonols include onions, grapes (and wine), berries, tomatoes and lettuce. [1]

one of several types of flavonoids found in plants and plant-based foods

Fisetin and its antioxidant properties

Flavonoids help your body regulate cellular activity. As a source of antioxidants, they help combat oxidative stress caused by free radicals in our bodies.

Oxidative stress is when there is an excess of oxygen reactive species (ROS) in cells and tissues, hindering your body’s ability to detoxify. 

Our bodies naturally produce ROS in oxygen and cellular metabolism, but environmental stressors (such as pollution) and xenobiotics can trigger a rise in ROS production.

This imbalance of ROS in your cells can lead to cell and tissue damage – which contribute to several degenerative conditions such as cancer. [2]

Antioxidants such as flavonoids fight oxidative stress, so they protect our cells and systems from toxins and stressors, as well as harmful molecules. Like ROS, our bodies also naturally produce antioxidants, but we can take them in through external sources. [3]

One of the flavonoids that benefit our bodies is fisetin.

Fisetin’s chemical structure is 3,7,3’,4’ tetrahydroxyflavone. It is a metabolic byproduct in plants, commonly present in foods such as apples, strawberries, kale and onions – although in low concentrations. A person’s average daily intake of fisetin is about 0.4mg. [4]

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Benefits of fisetin

As a polyphenolic molecule and flavonoid, fisetin has potential as an alternative medical and therapeutic approach to the management of chronic, non-communicable diseases. In particular, fisetin is a bioactive polyphenol that can hinder the progress of several non-communicable diseases.


Various physiological and pathological conditions cause inflammation in our bodies. Inflammation is a prolonged, impaired immune response that can lead to diseases such as diabetes, lung disease, immunological conditions and cancer.

In the treatment of inflammation, neutraceuticals have begun attracting attention. One such compound is fisetin. It has shown potential as a chemo-preventative, anti-metastatic, antioxidant and anti-inflammatory.

Presently, inflammation is treated by steroidal anti-inflammatory drugs (SAIDs) and non-steroidal anti-inflammatory drugs (NSAIDs).

But fisetin as a bioactive dietary agent may also prevent or help treat inflammatory responses and chronic inflammation. By consuming fisetin-rich foods, a person might reduce inflammatory responses in their bodies. [5]


In terms of cancers, fisetin can deter or hinder angiogenesis, metastasis and inflammation. This suggests that the flavonoid can help prevent and manage malignancies in the human body. 

Fisetin also exhibits biological activity linked to protecting your body’s macromolecules against stress.

Additionally, it has the potential to act as an anti-inflammatory, chemoprotective or chemotherapeutic and senotherapeutic agent. This means it could be beneficial as an anti-cancer and antiaging compound. [6]

Current cancer treatments – including radiation therapy and chemotherapy – destroy both cancer cells and healthy cells and cause serious side effects in the body.

But nutritional compounds have begun emerging as ways to both prevent the development of cancer and mitigate the side-effects of treatment.

Studies have shown a synergistic effect between fisetin and cancer treatments. Fisetin can help increase apoptosis in cancer cells, as well as suppress cell invasion and metastasis. It also causes autophagic cell death. 

Additionally, the flavonoid can act as a chemotherapeutic agent by regulating signal pathways in the body. [7]


This flavonoid also has a role as a senolytic – a compound that kills senescent cells. Senescence is a mechanism in our body that prevents the replication of damaged DNA.

While that is generally beneficial, senescent cells have demonstrated an association with aging and age-related diseases. 

Of all flavonoids, fisetin is the most potent senolytic. It can reduce senescence in human adipose tissues and has been shown to restore tissue homeostasis in mice. [8]

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Side effects of fisetin 

Due to limited research, there are no known adverse effects of fisetin on the human body as of yet. Scientists only have a small pool of clinical trial data regarding the short- and long-term effects of fisetin, whether consumed naturally or taken as a supplement.

There are, however, promising signs in animal and laboratory studies.

Dosage of fisetin

There is no set dose for fisetin just yet. The amount in µg/g in common fruits and vegetables varies. Strawberries contain 160µg/g, apples 26.9µg/g, onions 4.8µg/g and grapes 3.9µg/g. 

Fisetin supplements generally fall in the 100-mg range – significantly higher than regular dietary sources. There have been no studies yet on the benefits and side effects of supplements in humans. [9]

Foods rich in fisetin

Fisetin, often hailed for its multiple health benefits, can be found in various natural food sources. For those looking to enrich their diet with this potent flavonoid, here’s a list of foods and a brief description of their fisetin content:

1. Strawberries

Among the most delicious sources of fisetin, strawberries top the chart. Consuming these juicy berries not only satisfies your sweet cravings but also ensures a healthy dose of fisetin.

2. Apples

The age-old saying, “An apple a day keeps the doctor away,” gains even more credibility. Apples, especially their skin, contain a commendable amount of fisetin.

3. Onions

These kitchen staples are more than just flavor enhancers. Onions, particularly the outer layers, offer a significant amount of fisetin.

4. Grapes

Another tasty source, grapes, especially the red and purple varieties, carry a good amount of fisetin. They make for a delightful snack while providing the added advantage of this flavonoid.

5. Persimmons

While not as commonly consumed as other fruits on this list, persimmons stand out for their fisetin content. These sweet and slightly tangy fruits can be a unique way to introduce more fisetin into your diet.

6. Tomatoes

Often a staple in salads, sandwiches, and various dishes, tomatoes also contribute to the fisetin count in our diet.

7. Kiwis

This vibrant green fruit, known for its unique taste and numerous health benefits, also offers a respectable amount of fisetin.

8. Cucumbers

Often enjoyed in refreshing summer salads, cucumbers are another source of fisetin. Including them regularly in meals can ensure a consistent intake of this beneficial compound.

Incorporating these foods into your daily meals and snacks can be an effective way to harness the potential benefits of fisetin. 

As with all dietary changes, it’s wise to maintain a balanced approach and consult with nutritionists or health professionals to get personalized advice.

Fisetin and longevity

As an antioxidant and antiaging compound, fisetin shows plenty of promise in extending the longevity of a person. It helps our bodies combat oxidative stress and remove toxins from external sources.

Fisetin can prevent and mitigate cellular and tissue damage and protect our cells from harmful molecules.

All this leads to the prevention or management of age-related diseases and chronic conditions.

In addition, fisetin has shown links to anti-cancer and anti-inflammatory responses in humans.

As fisetin comes into focus in longevity and medical research, hopefully, more studies emerge about the role of fisetin in antiaging and treatment of chronic conditions.

And with that information, we may see fisetin supplements and recommendations – as well as knowledge of its side effects – to improve our overall health and well-being.


Does fisetin actually work?

Fisetin has shown promise in scientific studies for its potential health benefits, especially in areas like cognitive health and inflammation. However, more comprehensive human trials are needed to conclusively determine its effectiveness across various health concerns.

Who should not take fisetin?

Pregnant and breastfeeding women, as well as individuals on certain medications, should exercise caution before taking fisetin. It’s essential to consult with a healthcare professional before starting any supplementation.

What happens if you take too much fisetin?

Excessive intake of fisetin might lead to potential side effects or adverse reactions. It’s crucial to follow recommended dosages and consult a healthcare provider if any concerns arise.

Is it safe to take fisetin every day?

While fisetin is generally considered safe for daily consumption within recommended dosages, individual reactions may vary. Always consult with a healthcare professional to determine the best regimen tailored to individual needs.

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Photograph: Microgen/ShutterStock
The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.