When is the best time to take fisetin?

Unprocessed fisetin dissolves poorly in water and is broken down quickly in the body. Without special processing, your body absorbs very little of it. This is a consistent finding across all four available studies. The question of 'when' to take fisetin is therefore less relevant than the question of 'in what form'.

Animal research shows that the formulation makes an enormous difference. Fisetin packaged in so-called nanoparticles or lipid vesicles achieved blood levels in mice that were many times higher than those produced by plain fisetin. With one type of lipid formulation, blood levels were even more than a hundred times higher than with unprocessed fisetin. A combination of a polymer nanoparticle with a solubility enhancer also produced a higher peak blood concentration in mice than pure fisetin.

All of these findings come from mouse studies. None of the available studies were conducted in humans. How these formulations perform in humans, and whether the dramatic absorption improvements seen in animal research also apply to humans, has not been investigated.

For everyday practice, this means that the best time to take fisetin cannot currently be derived from human research. What the studies do indicate is that ordinary fisetin capsules or tablets without a special formulation are likely absorbed only to a small degree. Whether improved formulations are available in consumer supplements, and whether they work the same way as the laboratory preparations used in these mouse studies, cannot be determined from this research.