What effects does fisetin have
Due to its molecular structure, fisetin has the ability to neutralize free radicals. Like other phytochemicals, this makes it a natural antioxidant. In addition, the molecule can increase the amount of glutathione, the most powerful antioxidant in many organisms.
In addition, it interacts with some inflammatory signaling pathways and has been shown to produce repeated anti-inflammatory properties in cell studies .
Where is fisetin found in food?
It occurs naturally in a variety of foods. Large amounts of the substance are found in strawberries, making this fruit one of the best natural sources of this flavonoid. In addition, fisetin is found in other fruits such as apples and mangoes as well as vegetables such as tomatoes, onions and cucumbers .
It is also found in manageable amounts in nuts and seeds as well as in wine and dark chocolate . Some spices, including turmeric and ginger, also contain fisetin.
As the fisetin content in foods varies, it's important to consume a variety of foods to ensure you're taking in a sufficient amount of this beneficial flavonoid. It's also worth noting that fisetin is sensitive to heat, so raw or minimally processed foods tend to have higher levels of this nutrient.
How much fisetin is contained in foods
Depending on the database, you will get slightly different results for this question. To give you a better overview, we have summarized some of the foods with the highest fisetin content. The table is based on this study:
| Lebensmittel | Fisetin content (µg/g fresh weight) |
| Erdbeeren | 160 |
| Apples | 26.9 |
| Trauben | 6.2 |
| Zwiebeln | 4.8 |
| Cucumbers | 5.2 |
| Tomaten | 0.8 |
| Kiwis | 2.0 |
| Pfirsiche | 1.9 |
Fisetin, quercetin and luteolin.
The three molecules, fisetin, quercetin and luteolin are all secondary plant substances. To give you a better overview of which fruits and vegetables contain which molecule, we have created another table for you here. The data comes from this study.
| Lebensmittel | Fisetin (μg/g fresh weight) | Quercetin (μg/g fresh weight) | Luteolin (μg/g fresh weight) |
| Green bean | not measured | 12.6 | 10.1 |
| Green bell pepper | not measured | 14.1 | 14.7 |
| Petersilie | not measured | 7.0 | 3.1 |
| Zwiebel | 4.8 | 337.0 | 1.9 |
| Lotoswurzel | 5.8 | 4.4 | 3.6 |
| lettuce | not measured | 4.8 | 5.2 |
| Orange | not measured | 17.5 | 1.0 |
| Kaki | 10.5 | not measured | 1.4 |
| Erdbeere | 160.0 | 6.9 | not measured |
The current research situation
Currently, research on fisetin is still based on animal studies, but the first studies on humans are already being carried out. We show you the areas of science in which fisetin is being researched:
Alzheimer
Alzheimer's disease is a serious and chronic disease of the brain, characterized by the deposition of a substance called amyloid beta and the excessive phosphorylation of proteins called tau in the brain . This accumulation leads to problems with brain function, particularly memory and cognition.
In a study on mice, the researchers investigated the protective effect of fisetin on the brains of mice, particularly in the context of Alzheimer's disease. They used a model of Alzheimer's disease in which the mice were injected with amyloid beta. This injection led to the known memory and synapse problems, as well as inflammation in the brain and degeneration of neurons.
The mice were then treated with fisetin, which was injected into the body (not directly into the brain). This treatment began one day after the amyloid beta injection and lasted for two weeks. The researchers found that the molecule significantly reduced the accumulation of amyloid beta as well as the hyperphosphorylation of tau proteins in the mice's brains. In addition, it helped to improve synaptic function, which led to an improvement in the mice's memory performance.
The treatment also activated pathways in the mice's brains that helped counteract the effects of amyloid beta.
Inhibition of inflammatory factors
In order to find out what properties fisetin has, the scientists carried out cell culture studies . This is basic research to better understand the biochemical relationships between the molecules. It is important to note that these studies initially only represent the basics of how molecules are likely to work.
What have the scientists found out about fisetin in the cell culture studies? Fisetin interacts in the cell culture studies via several pathways: It can reduce the production of pro-inflammatory cytokines and chemokines. In addition, fisetin may inhibit the activity of enzymes involved in inflammatory processes, such as cyclooxygenase-2 (COX-2) and lipoxygenase (LOX) , which are responsible for the production of inflammatory mediators.
Another mechanism by which fisetin may exert its anti-inflammatory effects is by modulating signaling pathways involved in inflammatory responses. Fisetin appears to inhibit the activation ofNF-kB (nuclear factor kappa B) in cell cultures , an important regulator of the inflammatory response, and modulate the activity of pathway proteins such as MAP kinases and PI3K/Akt that are involved in inflammatory processes .
In addition, fisetin has been shown to regulate the activity of inflammatory cells such as macrophages and neutrophils by reducing the release of inflammatory mediators such as nitric oxide (NO) and prostaglandins.
Fisetin & Longevity
In studies in mice, administration of fisetin late in life restored tissue homeostasis, reduced age-related pathology, and increased mean and maximum lifespan.
Even when administered to rodents equivalent to 75 human years, fisetin was able to extend lifespan by 10%. These results can probably be attributed to the effect of fisetin on the Hallmarks of Aging . The researchers were able to prove that fisetin has a life-prolonging effect not only in mice, but also in flies and worms. The life-prolonging effect in the animal studies is probably due to the activation of sirtuins . This family of genes, also known as longevity genes, is the focus of ageing research. Other molecules that also belong to the sirtuin activators are z.B. David Sinclair researched resveratrol.
To help you better understand the molecular background, we use the example of cellular senescence to show you how fisetin affects longevity in animal experiments.
Seneszenz
Before we explain the molecular interaction of fisetin, we will first explain the terms senescence and senolysis. In simple terms, senescence refers to old cells that no longer divide and remain in a kind of intermediate stage - not really dead, but not really alive either. Hence the nickname "zombie cells".
We find these senescent cells in our body at every stage of life and under certain circumstances they can even be useful. In old age, however, too many of these "zombie cells" probably accumulate and the body can no longer keep up with the elimination, the senolysis, of these cells. This increase in senescent cells leads to the activation of tissue hormones and messenger substances, which are summarized under the name SAPS. Animal studies in particular have shown that the elimination of "zombie cells" leads to a longer and healthier life. The molecules that can help the body to detect and eliminate such "zombie cells" are called senolytics.
Senolytics - the weapon against the "zombie cells"
Senolytic therapy, which aims to selectively eliminate senescent cells, has attracted a lot of attention in recent years. Much of it is still theory and has only been tested on animals.
According to this paper the senolytic potency of fisetin is higher than that of comparable flavonoids. One study showed that fisetin was able to destroy senescent cells in old mice and improve both their health and lifespan.
One of the molecular mechanisms behind the lifespan extension in the animal experiments is thought to be the DAF-16-induced stress response and induced autophagy. The altered autophagyis one of the Hallmarks of Aging and a reversal of this, could thus be one of the molecular reasons for the effects of fisetin in longevity research.
Did you know Autophagy is the body's ability to eliminate "old cells", as happens, for example, during fasting .
Quercesome - 20 times higher bioavailability compared to conventional quercetin powder. Thanks to phospholipids from the sunflower and natural vitamin C.
Side effects of Fisetin
Fisetin is generally considered to be well tolerated. As with all dietary supplements, side effects can occur, especially at higher doses. These include:
- Gastrointestinal discomfort: Some people may experience gastrointestinal problems such as stomach pain, nausea or diarrhea after taking Fisetin food supplements .
- Allergic reactions: Although rare, it is possible for people to have an allergic reaction to Fisetin. Symptoms of an allergic reaction may include skin rash, itching, difficulty breathing and swelling of the face or neck.
- Medication interactions: Fisetin could potentially interact with certain medications, especially those that affect blood clotting, such as blood thinners (anticoagulants). This could increase the risk of bleeding.
Fazit
Fisetin is a versatile and exciting molecule from the flavonoid group. It is being researched due to its senolytic properties. Fisetin is still mainly the subject of basic research, but this will certainly change in the near future.
