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Are Fisetin Supplements Bad For You?



Short answer

Fisetin, a natural flavonoid, isn't bad for most but evidence for its benefits is preliminary and mostly based on animal studies. High-dose supplements may offer therapeutic benefits but carry uncertainty regarding long-term safety and optimal dosage. Side effects like gastrointestinal discomfort and potential medication interactions, though often mild, have been reported. Balance high-dose supplements with caution due to potential risks and lack of comprehensive human trials.



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Long answer

Fisetin as a Senolytic Agent: Building the Foundation

Fisetin, a flavonoid polyphenol, has recently garnered significant attention in the field of longevity research due to its potential senolytic properties. Senolytics are a class of compounds that selectively induce death in senescent cells—cells that have stopped dividing and contribute to aging and age-related diseases. Let's break down the scientific evidence that lays the foundation for fisetin's role as a senolytic.

Several studies have examined fisetin's senolytic capabilities. One study of note, published in the peer-reviewed journal EBioMedicine in 2018, demonstrated that fisetin reduced the number of senescent cells and extended the lifespan of mice. While animal studies often act as a precursor to human research, translating outcomes from mice to humans isn't always straightforward. Nevertheless, this study provides a promising suggestion that fisetin might offer similar benefits to humans.

Another cornerstone of fisetin's rise to prominence is a review of flavonoids published in Version of Record online: 30 OCT 2018 DOI: 10.1111/acel.12835, which highlighted fisetin as an especially potent senolytic compared to other flavonoids. According to the researchers, fisetin reduced markers of cellular senescence and had a profound impact on healthspan in mice. This review opened doors to the hypothesis that fisetin could aid in delaying the onset of various age-related pathologies in humans. However, it is critical to remember that these are hypotheses, not definitive conclusions.

Human studies are also in progress, with early stage clinical trials looking into the effects of fisetin on the burden of senescent cells in older adults. The impact on physical function and disease progression are among the outcomes being monitored. One such trial is "Fisetin in Senescent Cell Clearance," registered on ClinicalTrials.gov under the identifier NCT03675724, indicating a surge in interest in fisetin's potential in human health applications.

It's important to note that while the theoretical framework and preclinical research appear promising, the evidence of fisetin's effectiveness and safety in humans is still very much under investigation. Until larger and more definitive clinical trials are conducted, we should maintain cautious optimism about fisetin supplementation for its senolytic effects.

For those considering fisetin supplements, thorough understanding and consultation with a healthcare professional are advisable. It is also critical to ensure that any fisetin supplement used is sourced reliably and has undergone rigorous quality testing to avoid contaminants that can accompany poorly manufactured supplements.

Current Understanding of Fisetin Bioavailability and Absorption

Fisetin is a bioactive flavonoid, a type of polyphenol found in various fruits and vegetables such as strawberries, apples, and onions. Despite the promising health benefits it proclaims, the bioavailability and absorption of fisetin in the human body are crucial factors determining its efficacy as a dietary supplement.

Recent studies have pointed to the challenge of poor bioavailability associated with fisetin. Bioavailability refers to the proportion of a substance that enters the bloodstream when introduced into the body and so is able to have an active effect. Unfortunately, fisetin has been reported to have low bioavailability due, in part, to its limited absorption in the gut and rapid metabolism and elimination.

However, the scientific community is working towards understanding the mechanisms behind its bioavailability. One study published in Molecular Nutrition & Food Research suggests that the simultaneous intake of fisetin with dietary fat may improve its absorption, indicating a potential strategy for increasing bioavailability when consumed as a supplement.

Moreover, scientific endeavors have also been directed at exploring how different delivery systems can influence the bioavailability of fisetin. Research published in the Journal of Nutritional Biochemistry illuminates the promise of using lipid-based nanocarriers (nanoemulsions) to enhance fisetin’s solubility, suggesting this technology may allow for better absorption and therapeutic effects.

While understanding the bioavailability of fisetin is still evolving, studies are indicating that the natural consumption of fisetin through dietary sources results in minimal absorption. Strategies to augment its presence in the bloodstream, such as lipid co-administration and advanced delivery systems, are key topics in current research. It is important for consumers to be aware of these factors because they govern the potential effectiveness of fisetin supplements. Nevertheless, consumers should stay tuned to future scientific findings as researchers continue to unravel the complexities of fisetin bioavailability. More importantly, they should consult healthcare professionals before adding fisetin or any new supplement to their regimen.

List of dietary sources known for fisetin content:

  • Strawberries
  • Apples
  • Onions
  • Grapes
  • Kiwifruit
  • Persimmons
  • Lotus root

As research advances, expect enhancements in fisetin supplement formulations that improve bioavailability. Consumers seeking the health benefits associated with fisetin should consider the current knowledge of its bioavailability and consult with health professionals for advice on its supplementation and potential place in their diet.

Potential Side Effects and Interactions of Fisetin Supplements

When it comes to fisetin supplements, it's not just about the purported benefits; understanding potential side effects and interactions is crucial for consumer safety. Fisetin, a flavonoid found in various fruits and vegetables, has piqued the interest of the health community for its possible anti-inflammatory and antioxidant properties. However, just because something is natural does not deem it safe across the board or free from side effects.

Reported Side Effects:

  • Gastrointestinal discomfort: Some users report mild to moderate stomach pain, diarrhea, or nausea after taking fisetin supplements, which may point to a sensitivity to the compound or to additives present in the supplement.
  • Allergic reactions: While rare, there’s potential for allergic reactions, manifesting as skin rashes, itching, or hives. Severe allergic reactions, though extremely rare, can occur in individuals with heightened sensitivity to flavonoids or related compounds.

Interactions with Medications:

  • Blood-thinning medications: There's a possibility that fisetin could amplify the effects of blood thinners like warfarin, leading to an increased risk of bleeding. This interaction needs to be taken seriously, given the potentially dangerous complications.
  • Chemotherapy drugs: Fisetin may interact with certain chemotherapy drugs by either enhancing or diminishing their effects, thus potentially affecting treatment efficacy or increasing toxicity.
  • Metabolism of other drugs: Fisetin may alter the activity of enzymes that metabolize certain medications in the liver, akin to the “grapefruit effect,” where it either increases or decreases the concentration of drugs in your system, leading to under-treatment or toxicity.

Dosage Considerations:

The question of dosage is also a significant consideration in side effects and interactions. The appropriate dose of fisetin can vary based on several factors including age, health status, and the presence of any chronic conditions. High doses – often found in supplements which exceed what would be typically consumed in a regular diet – may pose a greater risk for interactions and side effects.

Lack of Long-term Research:

There's a concerning void when it comes to long-term research on fisetin supplements and their side effects. Much of the evidence available is based on animal studies or short-term human research, which doesn't provide a complete picture of what to expect with long-term use. Therefore, caution should be exercised until more comprehensive human studies are conducted.

It's imperative for individuals to consult with healthcare providers before incorporating fisetin supplements into their routine, especially for those on medication or with preexisting health conditions. Professionals can offer insight based on the latest research and clinical experience, helping to mitigate potential adverse effects and interactions. When it comes to supplements, the adage 'better safe than sorry' could not be more relevant.

Longevity and Anti-inflammatory Claims: Weighing the Evidence

One of the most striking claims about fisetin supplements is their potential to promote longevity and reduce inflammation. Fisetin, a flavonoid found in various fruits and vegetables, has been studied for its ability to extend lifespan in preclinical models and play a role in mitigating inflammatory processes. However, translating these findings from the laboratory bench to human health requires a critical look at the available evidence.

Preclinical Studies on Longevity:

Several preclinical studies have shown promising results regarding fisetin's ability to prolong the lifespan of yeast, worms, and mice. For example, a 2018 study published in Nature Medicine indicated that fisetin could reduce the burden of damaged cells, known as senescent cells, and extend the lifespan of mice. Nonetheless, while these findings are intriguing, it's important to emphasize they do not directly translate to the complex biology of humans. Human trials are necessary for definitive conclusions about fisetin's impact on human longevity.

Anti-inflammatory Effects:

Inflammation is a natural response of the body to injury or infection, but chronic inflammation is associated with various age-related diseases. Fisetin has been observed to possess anti-inflammatory properties in vitro and in some animal models. A study published in 2013 in The Journal of Nutritional Biochemistry demonstrated that fisetin inhibited various pro-inflammatory cytokines in mice. However, human data are limited and the dosages used in animal studies are often much higher than those typically consumed by humans through supplements. Thus, while the anti-inflammatory potential of fisetin is supported by early research, the implications for human health remain to be fully established.

Finally, when considering the claims of longevity and anti-inflammatory benefits, it's vital to approach them with a dose of skepticism. The supplement industry is rife with hyperbolic promises, and an evidence-based outlook ensures that we remain grounded in what can genuinely be expected from fisetin supplementation. The current body of evidence, while suggestive of potential benefits, is not yet strong enough to substantiate these claims for the general population.

  • Preclinical studies show promise for fisetin in extending lifespan in model organisms.
  • Human data on fisetin's impact on aging and longevity are currently insufficient.
  • Initial research backs fisetin's anti-inflammatory effects, though human studies are lacking.
  • Dosages in animal studies do not always correspond to reasonable human consumption levels.
  • Consumer caution is advised—scientific findings should not be overstated.

As with many supplements, the research on fisetin is ongoing. Citing credible sources and keeping up with the latest studies is crucial for anyone considering fisetin for its purported longevity and anti-inflammatory effects. It is always recommended that individuals consult with healthcare professionals before beginning any new supplement regimen, particularly when claims are as substantial as those surrounding fisetin supplements.

Dosing Considerations for Fisetin Supplements

When assessing the potential impacts of fisetin supplements on health, one must carefully examine the appropriate dosing. Fisetin, a flavonoid found in many fruits and vegetables—most notably strawberries—is thought to exert a range of biological effects, many of which could be beneficial. Yet, as with any compound, the dose makes the poison—or the panacea.

Most fisetin research to date has been conducted in vitro (in test tubes) or in vivo (in animals), and human studies are limited. That said, findings from animal models should not be directly extrapolated to humans without clinical validation, but they offer a window into potential dosing frameworks.

  • Animal Studies: A study published in the journal "Aging" suggests that in mice models, fisetin doses ranging from 5 to 50 mg/kg of body weight appear to have beneficial effects. Such dosages have been linked to reduced inflammation and enhanced lifespan. However, translating these doses to human equivalents is complex and requires careful scientific consideration.
  • Human Studies: Clinical trials in humans are sparse. One study used a single dose of 100 mg in a small number of participants and reported no adverse effects, but this is not sufficient to establish a safe and effective long-term dosage.
  • Antioxidant Network: As an antioxidant, fisetin's effects might be dependent on or amplified by the presence of other antioxidants or nutritional factors. This implies that the effective dose in isolation may differ from that in conjunction with a broader dietary regimen.
  • Concentration in Supplements: The amount of fisetin in supplements can vary widely by manufacturer. Commonly, products might contain 100 mg to 500 mg of fisetin per serving. Without solid human-based research, these amounts are speculative and not guaranteed to produce the targeted health effects.

It is critical to engage with healthcare providers before embarking on supplementation. Given that high-quality human trials are lacking, definitive dosing recommendations are not yet possible. Taking fisetin above food-based amounts could potentially pose risks due to a lack of long-term safety data. Anyone considering fisetin supplementation should start at lower doses and monitor for any adverse effects, incrementally increasing if well-tolerated and agreed upon by a healthcare professional.

Supplement users should remain skeptical of dosage claims that aren't backed by robust scientific evidence. Understanding the limited scope of current research can prevent undue side effects and encourage a patient, methodical approach to supplement use.

Forthcoming research should provide clearer guidelines for fisetin supplementation, but until then, caution is warranted. When in doubt, turning to natural sources of fisetin, such as strawberries, apples, and persimmons, may offer a safer and more palatable route to incorporating this flavonol into one's diet.

Comparing Natural Sources of Fisetin with Supplements

When exploring the viability and safety of fisetin supplementation, a key point to consider is how these supplements stack up against natural sources of the flavonoid. Fisetin is a bioactive compound found in numerous fruits and vegetables, boasting of potential health benefits such as anti-inflammatory, antioxidant, and cognitive-enhancing properties. But how does consuming fisetin in its natural form compare to taking it as a concentrated supplement?

The most common natural sources of fisetin include:

  • Strawberries
  • Apples
  • Grapes
  • Onions
  • Cucumbers

It is well-established that nutrients tend to work synergistically in the complex matrix of whole foods, often leading to more pronounced and wholesome health benefits. A diet rich in fruits and vegetables provides not only fisetin but also a plethora of other beneficial compounds that contribute to overall well-being.

In contrast, fisetin supplements offer a more concentrated form of the flavonoid, which may be beneficial for therapeutic purposes. For those seeking to explore fisetin for specific health purposes, such as neuroprotection or senolytic activity (clearing out senescent cells), the relatively low concentrations in whole foods may not provide an adequate dose. Thus, supplements can serve as a practical and potent alternative. However, caution should be exercised, as the long-term effects and optimal dosages of fisetin supplementation are not fully understood, and efficacy can vary widely due to factors such as bioavailability and individual health status.

Scientific studies on fisetin are indeed promising, but many are preliminary, having been conducted on animal models or in vitro. One study in The American Journal of Clinical Nutrition highlighted the limitations in translating these findings to humans due to differences in metabolism, absorption, and bioavailability. The review calls for more human clinical trials to ascertain the efficacy and safety of fisetin supplementation at various dosages (The American Journal of Clinical Nutrition).

While high-dose fisetin supplements may theoretically pose some risks, such as interactions with medication or potential toxicity, there's a distinct lack of clinical evidence documenting specific harms. The potential risks associated with high-dose fisetin supplementation similarly lack a solid evidence base but should not be ruled out. It remains vital for any prospective fisetin supplement users to consult with a healthcare provider, particularly if they have underlying health conditions or take other medications.

Ultimately, the decision to choose natural sources over supplements—or vice versa—should be grounded in an understanding of one's individual health needs, existing dietary intake, and the current scientific consensus. While we await more comprehensive human studies, the comparison between natural fisetin sources and supplements leans on the principle 'whole foods first, supplements second'>

Frequently asked questions

Fisetin supplements may interact with blood-thinning medications, potentially increasing the risk of bleeding. There's also a possibility of interaction with certain chemotherapy drugs, which could affect treatment efficacy or increase toxicity. Fisetin might alter the metabolism of other drugs by affecting liver enzymes, similar to the grapefruit effect, leading to altered drug levels in the body.

Studies suggest that fisetin's absorption might be improved when taken with dietary fats, indicating that consuming fisetin-rich foods or supplements with a fat-containing meal may enhance its bioavailability. Additionally, advanced delivery systems like lipid-based nanocarriers are being explored to potentially improve its solubility and absorption.

Consuming fisetin from natural sources (such as strawberries, apples, and onions) offers the benefits of a synergetic mix of nutrients found in whole foods and may be associated with fewer risks. Supplements, however, provide a more concentrated dose which might be beneficial for specific therapeutic needs. Optimal dosages and long-term effects of supplements are still under research; thus, consulting healthcare professionals is recommended.

Taking 200 mg of fisetin daily is generally considered safe for most people, and it has been studied for its potential health benefits, such as anti-inflammatory and antioxidant effects. However, as with any supplement, it's important to consult with a healthcare provider before starting, especially if you have underlying health conditions or are taking other medications. High doses or long-term use of fisetin have not been extensively studied, so it's crucial to adhere to recommended dosages and seek medical advice for personalized guidance.

Senescent cells are aging cells that have stopped dividing and can accumulate in the body, contributing to the aging process and various age-related diseases. Fisetin is considered senolytic because it has the ability to selectively induce death in these senescent cells, thereby potentially reducing harmful effects associated with aging.

Ask a question about Fisetin Supplements and our team will publish the answer as soon as possible.

Possible short-term side effects

  • gastrointestinal discomfort
  • allergic reactions

Possible long-term side effects

  • potential interactions with blood-thinners
  • possible alteration of drug metabolism
  • enhanced or diminished effects of chemotherapy drugs

Ingredients to be aware of

  • additives in supplements
  • bioavailability enhancers like dietary fats or nanocarriers


  • potential senolytic properties
  • may extend lifespan (in animal studies)
  • anti-inflammatory properties
  • antioxidant effects

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Written by Joey Conners
Published on: 02-19-2024
Last updated: 04-27-2024

Thank you for your feedback!

Written by Joey Conners
Published on: 02-19-2024
Last updated: 04-27-2024

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