Quercetin is a flavonoid – a natural pigment found in onions, apples, berries, and capers. It is one of the most studied anti-inflammatory substances in the plant kingdom and has received increasing attention in longevity research in recent years, partly for its role as a senolytic – a substance that helps the body clear out aging cells.
What does quercetin do?
Quercetin works in several parallel ways. As an anti-inflammatory substance, it inhibits the production of prostaglandins and leukotrienes – signaling molecules that drive inflammation. As an antioxidant, it neutralizes free radicals and protects cells from oxidative stress. As an antihistamine, it stabilizes mast cells and reduces histamine release, which can be relevant in allergies.
The senolytic interest concerns quercetin's ability to selectively induce apoptosis – programmed cell death – in senescent cells that have stopped dividing but refuse to die and instead drive inflammation in surrounding tissue. Combined with dasatinib, quercetin has shown senolytic effect in early human studies.
Quercetin and the immune system
Quercetin is a natural zinc ionophore – it helps zinc enter cells. Zinc is crucial for immune function but has difficulty crossing the cell membrane on its own. Quercetin acts as a transporter. This is why quercetin and zinc are often combined in the same supplement – they enhance each other's effects.
Bioavailability – an important choice
Quercetin is relatively poorly absorbed in its basic form. Quercetin dihydrate and quercetin phytosome (bound to lecithin phospholipids) are forms with better bioavailability. Taking quercetin with a fat-containing meal also improves absorption. A common dose in studies is 500–1000 mg per day. Quercetin is often combined with bromelain and vitamin C for further enhanced absorption.
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