Benefits
Dietary myricetin intake and blood sugar outcomes in population studies
In a European case-cohort of 12,403 people who developed type 2 diabetes and a 16,154-person subcohort, the top fifth of myricetin intake (median about 5.4 mg a day) had 23 percent lower risk than the bottom fifth. A Finnish cohort of 10,054 adults saw a similar trend that was not significant, and US cohorts found no link. These diet studies cannot show cause.
Blood sugar and blood lipids in mouse studies
A pooled analysis of 21 mouse studies (514 mice) of myricetin in models of metabolic disease found lower blood glucose, insulin, triglycerides, total cholesterol and LDL cholesterol; HDL cholesterol did not change significantly. No human trial has tested whether isolated myricetin does the same.
Insulin release and pancreatic beta-cell signaling in laboratory and rat studies
Myricetin acted on the GLP-1 receptor and raised insulin release in isolated islets, and long-term oral dosing had glucose-regulating effects in rats. In insulin-making cells and rat islets exposed to high glucose, it reduced cell death linked to the enzyme CDK5. These are laboratory and animal results only.
Antioxidant activity in laboratory studies
Myricetin scavenges free radicals and protects fats from oxidation in laboratory tests, which is why it has been used to keep oils from going rancid. At high concentrations it can act as a pro-oxidant instead. In a small trial, a blend containing myricetin raised a blood antioxidant measure versus placebo, but the blend's effect cannot be credited to myricetin.
Platelet activity in laboratory and mouse studies
In tests on human platelets, myricetin reduced platelet clumping triggered by collagen and thrombin by blocking the platelet fibrinogen receptor. In mice it slowed clot formation in small vessels without lengthening bleeding time. Whether supplement doses do this in people has not been studied.
Mechanism of action
Slower breakdown and uptake of dietary sugars (laboratory)
Reviews of laboratory work describe myricetin inhibiting the digestion of starches and sugars and the uptake of glucose into cells. These enzyme and cell findings have not been shown to change blood sugar in people.
GLP-1 receptor activation (laboratory and rat)
In receptor and islet experiments, myricetin acted as a GLP-1 receptor agonist and raised glucose-stimulated insulin release, and long-term oral dosing had glucose-regulating effects in Wistar rats. It has not been tested this way in people.
Beta-cell protection through CDK5 inhibition (laboratory)
In INS-1 insulin-making cells and isolated rat islets under high glucose, myricetin reduced endoplasmic reticulum stress and cell death, restored PDX1 and SERCA2b, and was predicted by docking to bind CDK5. This is cell and islet work only.
Radical scavenging and pro-oxidant chemistry
Laboratory studies show myricetin scavenging free radicals and binding iron, which relates to its many hydroxyl groups. In some test systems with iron complexes and no vitamin C, higher concentrations generated reactive oxygen species instead.
Blocking the platelet fibrinogen receptor (laboratory and mouse)
Myricetin inhibited activation of integrin αIIbβ3, the receptor platelets use to bind fibrinogen, and lowered calcium release and P-selectin in human platelets in vitro. In mice it delayed platelet plug formation in mesenteric vessels.
Clinical trials
Prospective case-cohort study using dietary questionnaires; observational, so it cannot show cause, and the authors report no conflicts of interest. (Zamora-Ros et al. 2014, J Nutr)
12,403 people who developed type 2 diabetes and a center-stratified subcohort of 16,154 adults, drawn from 340,234 participants in 26 centers. Mean myricetin intake was 2.3 mg a day, mainly from tea (51.8 percent) and wine (22.1 percent).
The highest fifth of myricetin intake (median 5.38 mg a day) had a hazard ratio of 0.77 (95% CI 0.64 to 0.93; P-trend = 0.001) versus the lowest fifth. Kaempferol showed a significant trend, and isorhamnetin and quercetin showed no clear association.
Prospective cohort study with dietary history interviews and national register follow-up; observational. (Knekt et al. 2002, Am J Clin Nutr)
10,054 Finnish men and women whose flavonoid intake was estimated mainly from Finnish food composition data.
Higher myricetin intake showed a trend toward lower risk of type 2 diabetes that did not reach significance (relative risk 0.79, 95% CI 0.62 to 1.00; P for trend = 0.07, highest versus lowest quartile).
Randomized, single-blind, placebo-controlled trial of AGfit3 (Alchimia Innovazione srl), a commercial blend of silymarin, a Myrica cerifera extract supplying myricetin and pyrroloquinoline quinone sodium salt, taken with wine on day 1 and for 7 days; the placebo drink contained 1 g of vitamin C; myricetin is not the lead ingredient and its dose is not given in the abstract. Funded internally by the University of Padova and the Italian National Research Council. (Bosco et al. 2024, Nutrients)
20 healthy young adult wine drinkers (13 men, 7 women; mean age 21).
The primary outcome, reactive oxygen species production, did not differ between groups. Blood alcohol 2 hours after wine was lower with the blend than with placebo (0.015 versus 0.020 g/L), plasma total antioxidant capacity was higher at day 7, and urinary 8-isoprostane fell only with the blend. Urinary ethyl glucuronide did not differ between groups.
Four-arm 1-week study indexed by PubMed as a randomized controlled trial: placebo or Emulin, each with or without metformin, 10 per group; the abstract reports percentage changes without between-group statistics or blinding details, and the first author is affiliated with ATM Metabolics LLC. Myricetin is one of three ingredients and its dose is not given in the abstract. (Ahrens et al. 2013, J Med Food)
40 adults with type 2 diabetes.
Fasting glucose, 2-hour after-meal glucose, peak glucose and glucose area under the curve after a 50 g glucose drink rose 5 to 13 percent in the placebo-only group and fell 1 to 5 percent in the Emulin-only group.
Randomized, double-blind, placebo-controlled 4-week trial of Blueberin, 300 mg doses each supplying 250 mg chlorogenic acid from blueberry leaves and 50 mg myricetin, taken three times a day before meals; chlorogenic acid is the larger component, so myricetin is not the lead. The abstract reports within-group changes and no between-group test, and does not state funding sources. (Abidov et al. 2006, Georgian Med News)
42 adults with type 2 diabetes (mean age 46, BMI 25); the title describes female volunteers.
Fasting plasma glucose fell from 143 to 104 (reported in mg/L) with Blueberin (p<0.001 within group) and changed from 138 to 126 with placebo (not significant). C-reactive protein and the liver enzymes ALT, AST and GGT also fell within the Blueberin group.