isoquercitrin

PhytochemicalFlavonoidBest with a meal

What is it

Isoquercitrin (quercetin-3-glucoside) is a flavonol glycoside found in fruits, vegetables, and various herbs. It has substantially higher oral bioavailability than the aglycone quercetin. EMIQ (enzymatically modified isoquercitrin) is a more bioavailable form used in supplements.

Evidence for 2 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Seasonal allergic rhinitis

Good Evidence

Several RCTs of EMIQ and quercetin glycosides demonstrate reduction in allergy symptoms during pollen season.

Exercise recovery / endurance

Limited Evidence

Some trials show benefits for cycling performance and recovery markers; effects are modest.

How it works

Isoquercitrin is absorbed directly via sodium-dependent glucose transporters in the small intestine, then hydrolyzed to quercetin and metabolized to glucuronide/sulfate conjugates. Compared to free quercetin (bioavailability ~2%), isoquercitrin is absorbed at 10-25%, and EMIQ at even higher rates. The absorbed quercetin and its metabolites exert antioxidant, anti-inflammatory, antihistamine, and capillary-stabilizing effects. Clinical trials support uses for seasonal allergies, exercise recovery, and blood pressure.

Dosage

EMIQ doses in studies: 100-300 mg/day. Other isoquercitrin forms: 100-500 mg/day, often providing 50-250 mg quercetin equivalents.

When and how to take it

WHEN: With meals, often around exercise for athletic applications. Allergy support: take in advance during exposure season.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Isoquercitrin

Natural quercetin-3-glucoside form.

Higher absorption than free quercetin

EMIQ (enzymatically modified isoquercitrin)

Enhanced delivery for clinical applications.

Highest oral bioavailability quercetin form

Safety

Generally well tolerated. Headache, tingling, mild GI symptoms uncommon. High doses may cause renal effects in susceptible individuals.

Who should be cautious

Avoid high-dose supplements in pregnancy and lactation. Caution with multiple medications. People with kidney disease should avoid high doses.

Interactions

Quercetin and its glycosides inhibit CYP3A4, CYP2C9, and P-glycoprotein, with theoretical interactions affecting statins, calcium channel blockers, cyclosporine, and anticoagulants. May interact with quinolone antibiotics.

Food sources

Onions

Amount
Variable
%DV
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Apples

Amount
Variable
%DV
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Mango

Amount
Variable
%DV
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Frequently asked questions

Is EMIQ better than quercetin?⌄

EMIQ has substantially higher oral bioavailability than free quercetin, making it more efficient on a dose-for-dose basis.

Does isoquercitrin help with allergies?⌄

Multiple trials suggest modest benefit for seasonal allergic rhinitis when started before peak pollen exposure.

References

isoquercitrin on Wikidata — Wikidata link

isoquercitrin (ChEBI:28299) — ChEBI link

isoquercitrin (PubChem CID 5484006) — PubChem link

isoquercitrin on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on isoquercitrin (PubMed search) — PubMed link

Track isoquercitrin with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.