Enzymatically Modified Isoquercitrin vs Quercetin
How enzymatically modified isoquercitrin and quercetin differ in potency, absorption, tolerance, and cost.
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Side by Side
| Enzymatically Modified Isoquercitrin (EMIQ) | Quercetin (Aglycone or Dihydrate) | |
|---|---|---|
| Absorption | Moderate | Low |
| How it is absorbed | Quercetin glucoside with added glucose units. Water soluble, and absorbed after hydrolysis in the small intestine, with much higher plasma quercetin than the aglycone in human studies. | Poorly water soluble and absorbed less well than the quercetin glucosides in onions. Absorbed quercetin is conjugated in the gut wall and liver. |
| Typical dose | Per product | 500-1,000 mg daily |
| Common uses | general flavonoid supplementation | allergy symptoms (marketed), blood pressure (small trials) |
| Side effects | None notable. | Headache, tingling. |
| Cost | Moderate | Low |
| Also called | isoquercetin, alpha-glycosyl isoquercitrin | quercetin dihydrate, anhydrous quercetin |
When to Choose Enzymatically Modified Isoquercitrin (EMIQ)
Choose enzymatically modified isoquercitrin when you want a water-soluble form. Mirrors the glucoside form that makes onion quercetin well absorbed.
Enzymatically Modified Isoquercitrin (EMIQ)
Water soluble and well absorbed in human studies. Less common on shelves.
What to look for: EMIQ or alpha-glycosyl isoquercitrin named, with quercetin-equivalent content stated.
Find on iHerb Affiliate linkWhen to Choose Quercetin (Aglycone or Dihydrate)
Choose quercetin when you want the form most trials used at the lowest cost. The standard form in most trials. Pairing with bromelain is common, but no human data show it improves absorption.
Quercetin (Aglycone or Dihydrate)
The form most trials used. Cheap and poorly absorbed.
What to look for: 500 mg capsules of quercetin dihydrate. Bromelain adds cost, not proven absorption.
Find on iHerb Affiliate linkProducts on Titrate
3,011 of the 214,745 labels in the NIH Dietary Supplement Label Database list quercetin as an active ingredient (1,502 on market). 495 are sold as quercetin products by name.
Quercetin does not have its own search category yet. Each product above links to its full label in the NIH database.
Related
References
Linus Pauling Institute Micronutrient Information Center, Oregon State University. Flavonoids.
Ferry DR, Smith A, Malkhandi J, et al. Phase I clinical trial of the flavonoid quercetin: pharmacokinetics and evidence for in vivo tyrosine kinase inhibition. Clin Cancer Res. 1996;2(4):659-668.
Heinz SA, Henson DA, Austin MD, Jin F, Nieman DC. Quercetin supplementation and upper respiratory tract infection: a randomized community clinical trial. Pharmacol Res. 2010;62(3):237-242.
Murota K, Matsuda N, Kashino Y, et al. alpha-Oligoglucosylation of a sugar moiety enhances the bioavailability of quercetin glucosides in humans. Arch Biochem Biophys. 2010;501(1):91-97.
Weng Z, Zhang B, Asadi S, et al. Quercetin is more effective than cromolyn in blocking human mast cell cytokine release and inhibits contact dermatitis and photosensitivity in humans. PLoS One. 2012;7(3):e33805.
Serban MC, Sahebkar A, Zanchetti A, et al. Effects of quercetin on blood pressure: a systematic review and meta-analysis of randomized controlled trials. J Am Heart Assoc. 2016;5(7):e002713.
Riva A, Ronchi M, Petrangolini G, Bosisio S, Allegrini P. Improved oral absorption of quercetin from quercetin phytosome, a new delivery system based on food grade lecithin. Eur J Drug Metab Pharmacokinet. 2019;44(2):169-177.
Di Pierro F, Derosa G, Maffioli P, et al. Possible therapeutic effects of adjuvant quercetin supplementation against early-stage COVID-19 infection: a prospective, randomized, controlled, and open-label study. Int J Gen Med. 2021;14:2359-2366.