Alpha-Glycosyl Isoquercetin

PhytochemicalFlavonoid

What is it

Alpha-glycosyl isoquercetin (AGIQ) is an enzymatically modified form of isoquercitrin (quercetin-3-O-glucoside) with additional glucose units added to increase water solubility and oral bioavailability. It is one of the more bioavailable forms of quercetin.

Evidence for 1 use

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

Antioxidant / anti-inflammatory

Limited Evidence

Quercetin has modest evidence for blood pressure reduction, antihistamine effects, and exercise performance markers. Effect sizes are small.

How it works

After ingestion, AGIQ is hydrolyzed in the GI tract to isoquercitrin and then to quercetin, which is absorbed. Compared to quercetin aglycone, AGIQ achieves substantially higher plasma quercetin levels. Quercetin is a flavonoid with antioxidant, anti-inflammatory, and antihistamine activity in lab studies. Clinical effects in humans are modest and most evident at higher doses. AGIQ is FDA-recognized as GRAS for use as a food antioxidant and bitterness masker.

Dosage

Studies use 200-500 mg/day. Specific dosing depends on indication.

When and how to take it

Can be taken with or without food. Splitting doses (morning and evening) may maintain steadier plasma levels.

1 commercial form

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

Alpha-glycosyl isoquercetin (AGIQ)

Found in higher-end quercetin and seasonal allergy supplements.

Several-fold higher plasma quercetin compared to quercetin aglycone.

Safety

Well tolerated at typical doses. Some studies in animals showed kidney/bladder effects at very high doses, but human safety at recommended supplement doses appears acceptable.

Who should be cautious

Avoid in pregnancy and breastfeeding due to limited safety data. Caution with prescription medications.

Interactions

Quercetin can inhibit CYP3A4 and P-glycoprotein, potentially altering levels of certain medications (cyclosporine, statins, some chemo drugs, beta blockers). May enhance the effect of warfarin slightly. Discuss with pharmacist if on prescription drugs.

Food sources

Quercetin: apples, onions, capers, berries

Amount
Variable
%DV
—

Frequently asked questions

Is AGIQ better absorbed than regular quercetin?⌄

Yes. Pharmacokinetic studies show several-fold higher plasma quercetin levels with AGIQ vs quercetin aglycone.

References

Alpha-Glycosyl Isoquercetin on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Alpha-Glycosyl Isoquercetin (PubMed search) — PubMed link

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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.