Quercetin

Applications with clinical evidence:

Senolytic (Dasatinib + Quercetin): the D+Q protocol is the most-studied senolytic combination in humans, selectively eliminating senescent cells from adipose tissue, endothelium, and other tissues. Allergy/asthma: 250-1,000 mg/day reduces seasonal allergy symptoms via mast cell stabilisation and reduced histamine release. Cardiovascular: meta-analyses show systolic blood pressure reduction (~3 mmHg) with doses ≥500 mg/day for ≥8 weeks. Antiviral: pre-clinical and clinical COVID-19 studies (combined with zinc and vitamin C) show reduced duration and severity. Quercetin acts as a zinc ionophore, facilitating its cellular entry where it inhibits viral RNA polymerase. Anti-inflammatory: reduces IL-6, TNF-α, CRP. Exercise: improves endurance and reduces post-exercise oxidative stress in controlled studies.

Bioavailability issue: free quercetin has very low oral bioavailability (<2%). Modern forms solve this: Quercefit (Phytosome), Sophora japonica diohydroquercetin, and EMIQ (mulberry extract). Bioavailability improves 4-20× with these formulations.

Typical doses: 500-1,000 mg/day divided into 2-3 doses, with fat (better absorption). In the senolytic D+Q protocol, 1,000 mg is used in intermittent dosing. Excellent safety; caution with anticoagulants (mild potentiation) and with active chemotherapy (some protocols require pause).