Antioxidants

Quercetin

Preliminary

Quercetin is a flavonoid abundant in onions, apples, and berries. It has antioxidant, anti-inflammatory, and natural antihistamine properties. It is commonly used for allergy support, immune balance, and cardiovascular health, with emerging interest in its senolytic potential.

How It Works

Quercetin functions through multiple mechanisms:

Antihistamine: Inhibits histamine release from mast cells and basophils, reducing allergic symptoms.
Anti-inflammatory: Inhibits NF-κB, COX-2, and lipoxygenase pathways, thereby reducing inflammatory mediator production.
Antioxidant: Potent free radical scavenger; protects lipids like LDL from oxidation.
Immune Modulation: Supports immune function while dampening excessive inflammatory responses.
Senolytic Activity: In combination with dasatinib, has been shown in preclinical studies to help clear senescent cells.
Zinc Ionophore: Facilitates zinc transport into cells, which may be relevant to antiviral effects.

Natural Food Sources

Food	Amount per Serving
Capers (raw)	180 mg per 100g
Red onion	32 mg per 100g
Red onion	23 mg per 100g
Kale	15 mg per 100g
Blueberries	4-5 mg per apple
Apples (with skin)	2-3 mg per cup

Safety Information

Contraindications

Significant kidney disease – quercetin may accumulate
Pregnancy/breastfeeding - insufficient safety data for high-dose supplements

Potential Side Effects

Headache (uncommon)
GI upset (uncommon)
GI upset (nausea, stomach discomfort) (rare)

Typical Dosage

Optimal: 1000 mg
Range: 500-1500 mg

Typical supplements provide 500–1,000 mg/day. Often combined with vitamin C (which enhances stability and absorption) or bromelain (for synergistic anti-inflammatory effects). Phytosome and EMIQ forms provide better bioavailability at lower milligram doses.

Quick Facts

Bioavailability: Standard quercetin has relatively low oral bioavailability (~2–5%) due to poor water solubility and first-pass metabolism. Absorption is improved when taken with fat, vitamin C, or as enhanced formulations such as phytosome or EMIQ.
Half-life: Plasma half-life is reported in the range of roughly 11–28 hours, allowing once- or twice-daily dosing in many supplement protocols.
Also known as: Quercetin Dihydrate, Quercetin Phytosome, EMIQ (Enzymatically Modified Isoquercitrin)

May Help With

Disclaimer: The information provided is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare provider before starting any supplement regimen.