Fisetin's lipophilic structure limits its aqueous solubility and oral bioavailability to 5–15% in standard capsule form. Pharmacokinetic studies show that fat co-administration improves Cmax 2–4-fold, while phytosome complexation can improve bioavailability 20–50-fold compared to the crystalline compound.

Does cooking or heating damage fisetin?

Fisetin is relatively heat-stable up to 150°C but is photodegradable. Supplements should be stored away from light. Food-derived fisetin in cooked strawberries may retain 70–80% activity.

Is piperine safe to combine with fisetin?

Generally yes. The main caution is that piperine also increases absorption of drugs, so if you take medications, check for interactions before adding piperine. For standalone fisetin supplementation, 5–20 mg piperine is considered safe.