Quercetin, a dietary flavonol known to be one of the most potent plant-derived antioxidants, has multiple biological actions, with preclinical studies showing anti-inflammatory, anti-thrombotic, and vasodilatory benefits.1 The limiting factor in quercetin’s clinical efficacy appears to be its poor bioavailability. Enzymatically modified isoquercitrin (EMIQ) is a mixture of quercetin monoglucoside and its alpha-oligoglucosides that has been shown to have significantly greater bioavailability than other available forms. In animals, EMIQ was shown to produce a 40-fold increase in Cmax (peak plasma concentration) and an 18-fold increase in the area under the curve compared to quercetin.2 In humans, EMIQ supplementation increased plasma concentrations to a significantly greater degree than other forms, including the aglycone and isoquercitrin (Q3G) forms.3
Randomized placebo-controlled trials have shown EMIQ to have clinical benefits not seen with less absorbable forms. In a recent crossover trial of volunteers at risk for cardiovascular disease (i.e., with elevated blood pressure, lipids, glucose, or waist circumference), EMIQ improved endothelial function (as measured by flow-mediated vasodilatation), a key risk factor for hypertension, atherosclerosis, and cardiovascular disease.4 American football players supplementing with whey protein had greater increases in lower limb muscle mass and antioxidant protection when consuming 42 mg of EMIQ per day compared to whey alone.5 Two trials found that EMIQ reduced medication use and ocular symptoms of hayfever due to Japanese cedar pollinosis.