Rankings / Immune & Inflammation
Quercetin
Immune & Inflammation · Flavonoid
Tier C+
Bottom line
Read Off Label grades Quercetin as C+ (5.5/10) based on weak evidence, low-med benefit magnitude, and a low-risk safety profile.
Native quercetin has <1% oral bioavailability — most trials use large doses or enhanced formulations.
Typical use: 500-1000 mg/day; phytosome form at lower doses — OTC.
What this is
Native quercetin has <1% oral bioavailability — most trials use large doses or enhanced formulations. The 'zinc ionophore' claim popularized during COVID was based on weak in vitro data. Reasonable adjunct for mast cell activation / allergic phenotypes.
Mechanism
Flavonol ubiquitous in plants (onions, apples, capers); broad antioxidant; mast cell stabilization; proposed zinc ionophore activity (controversial claims during COVID); mTOR/AMPK modulation
Dose & route
500-1000 mg/day; phytosome form at lower doses
Citations
- https://pubmed.ncbi.nlm.nih.gov/27187333/
- https://pubmed.ncbi.nlm.nih.gov/31261295/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7230406/
- https://pubmed.ncbi.nlm.nih.gov/41831318/
- https://pubmed.ncbi.nlm.nih.gov/41441223/
- https://clinicaltrials.gov/study/NCT01348204
- https://pubmed.ncbi.nlm.nih.gov/41913224/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7070905/
- https://pubmed.ncbi.nlm.nih.gov/26933622/
- https://www.ebiomedicine.com/article/S2352-3964(18)30373-6/fulltext
Links go to the source. If a link is dead or you want something re-checked, let me know.
Common questions
- Does Quercetin work?
- Read Off Label rates the evidence for Quercetin as Weak and the benefit magnitude as low-med, producing an overall grade of C+ (5.5/10). Native quercetin has <1% oral bioavailability — most trials use large doses or enhanced formulations.
- Is Quercetin safe?
- Quercetin has a low risk profile in published human data. Legal status: OTC. This is not medical advice — see the disclaimer.
- What is the typical dose for Quercetin?
- 500-1000 mg/day; phytosome form at lower doses
- How does Quercetin work?
- Flavonol ubiquitous in plants (onions, apples, capers); broad antioxidant; mast cell stabilization; proposed zinc ionophore activity (controversial claims during COVID); mTOR/AMPK modulation
This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.