Looking for something? We are here to help.

Should I be concerned about fisetin’s bioavailability?

Most polyphenols—fisetin included—are relatively poorly absorbed through the gut barrier. But science has been showing more and more that they can also act locally inside the gut and may exert effects through the gut-brain axis as well. So bioavailability is only part of the potential efficacy equation. Because of this, our science team puts much more weight on scientific studies evaluating body & brain responses over bioavailability. And, big picture, despite evidence suggesting poor bioavailability there are a lot of studies suggesting beneficial support for the brain & body even from poorly absorbed polyphenols. Even with quercetin, most of the senolytic studies to date have been with standard quercetin. We opted for Quercefit® because it was what was used in a human senolytic study, is being investigated in other human senolytic studies, and has been used in human clinical studies in other health areas (so has demonstrated brain & body support benefits)—so Quercefit® has much science behind it in addition to the evidence for its bioavailability.*

The data on the bioavailability of fisetin is a main reason that the Mayo Clinic chose to use a high dose of fisetin in their senolytic studies, and why we are recommending the 1400 mg/day dose of fisetin (which for a person of average weight matches the Mayo dose). In published animal studies of fisetin, oral fisetin in this human-equivalent dose range has supported the management of senescence cells, which is the main outcome we care about (not bioavailability). We think the recommended dose included in Qualia Senolytic is sufficient taking into account the data on fisetin’s low bioavailability, but we would not be as confident that the doses we've seen in other supplements claiming a senescent cell benefit (often 100 mg and sometimes a bit more) would provide the intended support.*

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

More Frequently Asked Questions