Benefits
Leg muscle mass with whey protein during athletic training
In 39 university American football players, 20 g of whey with 42 mg EMIQ six days a week for 4 months raised lower limb muscle mass by about 0.93 kg versus 0.26 kg with whey alone, one of two stated primary outcomes. Whole-body lean mass, the other, did not differ, nor did body weight or fat mass. The food company Morinaga, which prepared the supplements, funded the trial and employed four of its seven authors.
Muscle strength with resistance training in older adults
These trials used San-Ei Gen quercetin glycosides made by the same enzyme route but not named EMIQ in the papers. In 26 older adults who completed the trial (30 were randomized), 200 mg a day for 6 weeks of training raised knee extension force about 15% versus 5% on placebo, the primary outcome, without a change in muscle mass. In a company-funded 24-week trial, thigh muscle size, the primary outcome, did not change.
Eye comfort during cedar pollen season
Two small placebo-controlled Japanese trials gave about 100 mg EMIQ a day for 8 weeks to adults with cedar pollen allergy (20 and 24 people). An eye symptom score over the study was lower than on placebo in each, but neither abstract names a primary outcome or a correction for the many scores compared, and nose symptoms and blood IgE did not differ significantly. Five co-authors of both trials were from the maker.
Artery widening after a single dose
In 25 adults with at least one cardiovascular risk factor, a single EMIQ drink (about 4.9 mg per kg body weight) with breakfast raised flow-mediated dilation, a test of how well the arm artery widens, by 1.8 points versus placebo 1.5 hours later. Blood pressure and arterial stiffness did not change. The maker funded the study, and daily use was not tested.
Blood antioxidant markers with protein powder
After 4 months of whey with 42 mg EMIQ, athletes had a higher ratio of blood antioxidant capacity to oxidative stress than with whey alone, a secondary outcome. In a 7-day crossover of 9 adults, 42 mg EMIQ added to soy protein also lowered oxidative stress readings. Both trials were run with the food company Morinaga, and these are lab markers, not health outcomes.
Absorbed more readily than isoquercitrin or rutin
In volunteers, EMIQ raised blood quercetin metabolites quickly and was absorbed more efficiently than isoquercitrin or rutin, with the same pattern of breakdown products. A review of 31 human studies put this oligoglucoside form at about 2 times isoquercitrin and 20 times plain quercetin. Blood levels show uptake, not a health effect.
Mechanism of action
Glucose chains are trimmed before quercetin is absorbed
The extra glucose units make EMIQ water soluble. In the gut they are thought to be cut off by brush border enzymes such as maltase-glucoamylase, leaving isoquercitrin and then quercetin to be absorbed, mostly in the small intestine. Quercetin then circulates as glucuronide and sulfate conjugates, the same profile seen after isoquercitrin.
Motor unit activity during training
In the 6-week trial of the maker's quercetin glycosides with resistance training, higher-threshold motor units fired faster in the supplement group, and the change in their firing rate tracked the gain in knee extension force. This is a proposed explanation for the strength result, and it comes from one small trial.
Artery effect without a nitric oxide signal
Quercetin is proposed to support blood vessel function through nitric oxide. In the single-dose EMIQ study, blood markers of nitric oxide and oxidative stress did not change, so the reason for the higher flow-mediated dilation reading is not known.
Clinical trials
Randomized, controlled crossover trial (ACTRN12617001202358): one dose of 4.89 mg EMIQ per kg body weight (2 mg quercetin equivalent per kg) or a maltodextrin placebo in a flavored drink with a standard breakfast, visits at least 7 days apart; flow-mediated dilation was the primary endpoint; EMIQ prepared by and study funded by San-Ei Gen F.F.I., which the paper says had no role in design, analysis or writing (Bondonno et al. 2020, Br J Nutr)
25 adults in Australia (12 men, 13 women) with at least one cardiovascular risk factor, such as systolic blood pressure of 120 to 160 mmHg, raised fasting glucose or cholesterol, or a large waist.
Flow-mediated dilation 1.5 hours after the dose, the primary endpoint, was 1.80 percentage points higher after EMIQ than after placebo (95% CI 0.23 to 3.37; P = 0.025), and plasma quercetin metabolites were higher (P < 0.001). Blood pressure over 80 minutes (systolic P = 0.916), arterial stiffness, cognitive function and oxidative stress and nitric oxide markers did not differ. Only one dose was tested, and the study was powered only for the primary outcome.
Randomized, double-blind, placebo-controlled parallel-group trial: EMIQ (two capsules daily of 100 mg, as the abstract words it) or placebo for 8 weeks during the pollen season; five of the 17 authors (Koyanagi, Kai, Shimizu, Moriwaki, Suzuki) are listed at San-Ei-Gen F.F.I.; funding is not stated in the abstract (Kawai et al. 2009, Int Arch Allergy Immunol)
20 adults with Japanese cedar pollen allergy.
Over the whole study, total eye symptom and eye itching scores were lower with EMIQ than placebo (p < 0.05). Total symptom score was lower only in weeks 4 to 5, while nasal (p = 0.06), eye congestion (p = 0.08) and daily activity (p = 0.08) scores only trended lower. Serum IgE and cytokines did not fall significantly; oxidized LDL and the chemokine TARC fell. The abstract does not name a primary outcome or a correction for the many scores compared.
Randomized, double-blind, placebo-controlled parallel-group trial: 100 mg EMIQ a day or placebo for 8 weeks, starting 4 weeks before pollen release; nearly the same author list as the in-season trial, including the five co-authors listed there at San-Ei-Gen F.F.I. (Hirano et al. 2009, Allergol Int)
24 adults with Japanese cedar pollen allergy.
Over the whole study, the combined eye symptom plus medication score was lower with EMIQ (p < 0.05), and eye symptom and eye congestion scores were lower in weeks 5 to 6. Eye itching (p = 0.09) and tearing (p = 0.07) only trended lower, nasal symptoms did not differ, and serum IgE did not fall significantly, while blood quercetin rose. The abstract does not name a primary outcome.
Randomized, placebo-controlled, double-blind parallel trial, registered retrospectively (UMIN000036036): 20 g whey with 42 mg EMIQ or whey alone after exercise, 6 days a week for 4 months, body composition by DXA; stated primary outcomes were changes in lean mass and lower limb muscle mass; supported by Morinaga & Co., which prepared the supplements, and four of seven authors (Nishimura, Tsukamoto, Maruki-Uchida, Morita) were Morinaga employees (Omi et al. 2019, J Int Soc Sports Nutr)
39 Japanese male university American football players randomized (19 EMIQ with whey, 20 whey alone), average age 19.8; one of 40 recruits was excluded before randomization.
Of the two stated primary outcomes, lower limb muscle mass rose more with EMIQ (about 931 g versus 256 g; p = 0.021), while whole-body lean mass did not differ; no correction for two primaries was reported, though p = 0.021 would still pass a two-outcome Bonferroni threshold of 0.025. Lower limb fat-free mass (p = 0.031) and the BAP/d-ROMs antioxidant ratio (p = 0.028) were higher, and body mass, fat mass and lower limb fat mass did not differ. No adverse events were linked to the product.
Randomized, double-blind crossover trial (UMIN000044791): soy protein with or without 42 mg EMIQ for 7 days after mild exercise, with blood sampled over 4 hours on the last day; five of nine authors (Tsukiashi, Yamamoto T, Tanaka, Maruki-Uchida, Kawama) were at the R&D Institute of Morinaga & Co. (Omi et al. 2023, Amino Acids)
9 healthy adults.
Total plasma amino acids were higher with EMIQ at 0 and 120 minutes, and easily oxidized amino acids at 120 minutes, out of nine sampling times. Oxidative stress readings were lower and plasma testosterone was higher with EMIQ. No muscle or performance outcome was measured, and with 9 people these are early marker findings.
Randomized, double-blind, placebo-controlled parallel-group trial: 500 mL a day of a drink with 110 mg quercetin glycosides (EMIQ, standardized as isoquercitrin) or a matching drink for 40 weeks; MMSE total score was the primary endpoint; test drinks supplied by Suntory Beverage & Food, three of five authors at the Suntory research institute; the paper reports no external funding and no conflicts of interest (Nakamura et al. 2022, Eur Rev Med Pharmacol Sci)
80 healthy men and women aged 60 to 75 without cognitive impairment who noticed age-related forgetfulness; 71 completed and 68 were analyzed for efficacy.
MMSE total scores, the primary endpoint, rose in both groups with no difference between them. Reaction time on the Cognitrax battery improved more with the EMIQ drink than with placebo, while the overall Cognitrax index did not differ between groups. Brain blood volume, blood flow and activity measures did not differ significantly. Frequent urination was judged possibly related to the extra fluid.