What Is Quercetin?
Quercetin is one of the most abundant flavonoids in the human diet, found in onions, apples, capers, berries, broccoli, and green tea. It has been studied extensively for anti-inflammatory, antihistamine, antiviral, cardiovascular protective, and—most recently—senolytic properties.
As a senolytic, quercetin gained prominence from its role in the dasatinib + quercetin (D+Q) combination protocol developed by the Kirkland lab at Mayo Clinic. While quercetin alone has moderate senolytic activity, in combination with the cancer drug dasatinib, it is the most potent senolytic combination that has been tested in human clinical trials.
Multi-Target Mechanisms
- Senolytic: Inhibits PI3K/AKT survival pathways in senescent cells; inhibits BCL-2 family anti-apoptotic proteins; selectively induces apoptosis in senescent cells
- Anti-inflammatory: Inhibits NF-κB transcription factor; reduces COX-2, LOX-5, and phospholipase A2; decreases IL-6, TNF-α, IL-1β production
- Antihistamine: Stabilises mast cells and basophils; inhibits histamine release; inhibits Th2 cytokine production driving allergic response
- Antiviral: Inhibits viral entry and replication (studied against influenza, SARS-CoV-2, and other respiratory viruses)
- Antioxidant: Direct radical scavenging; chelates transition metals (iron, copper) that catalyse oxidative damage
- Zinc ionophore: Quercetin helps transport zinc into cells, enhancing zinc's antiviral and immune effects—a popular COVID-19 prevention protocol
India has one of the highest allergy burdens globally, with rising prevalence of seasonal rhinitis, asthma, and food allergies driven by urbanisation and air pollution. Quercetin's mast cell stabilising and histamine-inhibiting properties make it particularly relevant. Studies show 500 mg twice daily reduces allergic rhinitis symptoms and bronchial hyperreactivity. Combined with India's high chronic disease burden (CVD, T2D), quercetin's broad anti-inflammatory effects offer multiple simultaneous benefits.
Why Bromelain Matters
Quercetin has notoriously poor and variable bioavailability. Standard quercetin aglycone is absorbed at approximately 1–5%, with most metabolised by gut bacteria or conjugated in the gut mucosa before entering circulation. Bromelain—a cysteine protease from pineapple stem—improves quercetin absorption by:
- Inhibiting intestinal brush border enzymes that conjugate quercetin
- Enhancing gut permeability transiently, allowing more intact quercetin to cross
- Providing independent anti-inflammatory benefits (synergistic with quercetin)
The combination increases quercetin plasma concentrations by approximately 200–300% vs quercetin alone. The standard ratio is 500 mg quercetin : 100–400 mg bromelain.
Quercetin Phytosome: Superior Bioavailability
QUERCEFIT (quercetin phytosome, bound to sunflower phospholipids) achieves ~20× better oral bioavailability than standard quercetin. A 100 mg dose of QUERCEFIT may be equivalent to 2000 mg of standard quercetin in plasma levels. This formulation is more expensive but dramatically reduces the dose needed. Available in some premium supplements shipped to India.
Dosing Summary
| Use Case | Dose | Form | Timing |
|---|---|---|---|
| Anti-inflammatory / longevity | 500 mg twice daily | + Bromelain 400 mg | With meals |
| Allergy / antihistamine | 500 mg before exposure | Standard or phytosome | 30 min before trigger |
| Senolytic (standalone) | 1000 mg twice daily × 2 days/month | + Bromelain or phytosome | With fat-rich meal |
| Zinc ionophore (immune) | 500 mg + 15–30 mg zinc | With bromelain | With meals |
| QUERCEFIT phytosome | 250 mg once or twice daily | Phytosome form | With food |
Frequently Asked Questions
Is quercetin effective for allergies and inflammation in India?
Yes. Quercetin stabilises mast cells and inhibits histamine release, reducing allergic rhinitis, skin allergies, and bronchial reactivity. It also inhibits NF-κB and COX-2, reducing inflammatory cytokines relevant to chronic diseases prevalent in India. Clinical studies show 500 mg twice daily reduces hay fever symptoms comparably to low-dose cetirizine. For India's high-pollution, high-allergy environment, quercetin is one of the most practically useful anti-inflammatory supplements.
Quercetin vs fisetin – which is the better senolytic?
Fisetin is the stronger standalone senolytic (approximately 3–5× more potent in comparative animal studies). However, quercetin combined with dasatinib (D+Q) is the most potent senolytic combination in human trials. Without prescription dasatinib, fisetin is preferred for senolysis. Quercetin remains highly valuable for its anti-inflammatory, antihistamine, and antiviral effects even without strong standalone senolytic activity.
Why take quercetin with bromelain?
Quercetin has very poor oral bioavailability (~1–5%). Bromelain inhibits gut enzymes that conjugate quercetin, increasing plasma concentration by 2–3×. Most quality quercetin products include bromelain (typical ratio: 500 mg quercetin : 100–400 mg bromelain). Quercetin phytosome (QUERCEFIT) achieves 20× better bioavailability without bromelain but costs more. Both forms work; choose based on budget and whether you want bromelain's additional anti-inflammatory benefits.
What is the correct quercetin daily dosage?
For anti-inflammatory and antioxidant effects: 500 mg twice daily with bromelain and food. For allergy: 500 mg 30 minutes before anticipated allergen exposure. For senolytic protocol: 1000 mg twice daily for 2 consecutive days per month. Quercetin phytosome: 250 mg once or twice daily (equivalent to much higher standard quercetin dose). Long-term safety established up to 1000 mg/day; higher doses require medical oversight.