Quercetin
Also known as: Quercetin Dihydrate, Quercetine
One of the most prevalent dietary flavonoids — anti-inflammatory, antiviral, and potentially senolytic.
What it is
Quercetin is a flavonoid found in apples, onions, berries, green tea, and many other plant foods. It is one of the most consumed dietary antioxidants and has been studied for applications ranging from allergies to viral infections to cancer prevention. More recently, it has attracted attention as a potential senolytic — a compound that selectively eliminates senescent ('zombie') cells implicated in aging.
How it works
Quercetin inhibits mast cell histamine release (relevant to allergies), blocks viral replication through inhibition of viral proteases (antiviral activity), inhibits NF-κB and COX-2 (anti-inflammatory), and may trigger apoptosis in senescent cells through inhibition of anti-apoptotic proteins. It also inhibits COMT (catechol-O-methyltransferase), potentially raising dopamine and norepinephrine levels. Bioavailability is poor and requires formulation enhancement.
Clinical dose range
500–1,000 mg/day
Standard quercetin has poor oral bioavailability (~17%). Take with food to improve absorption. Bioavailability-enhanced forms (phytosomes, nanoparticles) may allow lower effective doses. For senolytic protocols, some researchers use high intermittent dosing (1,000 mg daily for short cycles) rather than continuous supplementation.
Forms comparison
What to look for on the label
- Bioavailability enhancement specified (phytosome, bromelain, or vitamin C combination)
- Third-party tested for quercetin identity and actives
- Dose 500 mg per serving minimum for standard form; lower if phytosome
- Clear disclosure of the quercetin compound form
Health goals supported
Safety & dosing notes
Generally well tolerated. May interact with antibiotics (particularly fluoroquinolones) and cyclosporine. High doses may cause headache or GI discomfort. Theoretical concern about hormonal activity at very high doses. Generally safe at 500–1,000 mg/day.
SuppsBuddy checks for bioavailability enhancement given quercetin's poor oral absorption. Standard quercetin without enhancement is noted as requiring higher doses to achieve clinical effect. Phytosome forms receive the highest form quality score.
Frequently asked questions
What is Quercetin?
Quercetin is a flavonoid found in apples, onions, berries, green tea, and many other plant foods. It is one of the most consumed dietary antioxidants and has been studied for applications ranging from allergies to viral infections to cancer prevention. More recently, it has attracted attention as a potential senolytic — a compound that selectively eliminates senescent ('zombie') cells implicated in aging.
How does Quercetin work?
Quercetin inhibits mast cell histamine release (relevant to allergies), blocks viral replication through inhibition of viral proteases (antiviral activity), inhibits NF-κB and COX-2 (anti-inflammatory), and may trigger apoptosis in senescent cells through inhibition of anti-apoptotic proteins. It also inhibits COMT (catechol-O-methyltransferase), potentially raising dopamine and norepinephrine levels. Bioavailability is poor and requires formulation enhancement.
What is the typical clinical dose range for Quercetin?
500–1,000 mg/day. Standard quercetin has poor oral bioavailability (~17%). Take with food to improve absorption. Bioavailability-enhanced forms (phytosomes, nanoparticles) may allow lower effective doses. For senolytic protocols, some researchers use high intermittent dosing (1,000 mg daily for short cycles) rather than continuous supplementation.
What forms of Quercetin should I look for?
Quercetin Phytosome (QUERCEFIT®): ~20× better bioavailability than standard quercetin; phospholipid complexation | Quercetin + Bromelain: Bromelain enhances quercetin absorption and adds complementary anti-inflammatory activity | Quercetin Dihydrate: Standard form; poor bioavailability limits effectiveness; widely used but requires higher doses | Quercetin 500–1000 mg with Vitamin C: Vitamin C regenerates oxidized quercetin and modestly enhances absorption
Is Quercetin safe?
Generally well tolerated. May interact with antibiotics (particularly fluoroquinolones) and cyclosporine. High doses may cause headache or GI discomfort. Theoretical concern about hormonal activity at very high doses. Generally safe at 500–1,000 mg/day. This information is educational and is not medical advice.
How does SuppsBuddy evaluate Quercetin?
SuppsBuddy checks for bioavailability enhancement given quercetin's poor oral absorption. Standard quercetin without enhancement is noted as requiring higher doses to achieve clinical effect. Phytosome forms receive the highest form quality score.
Related ingredients
This page is for educational purposes only. These statements have not been evaluated by the FDA. This information is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before starting any supplement.