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Br J Nutr. 2019 Aug 20:1-8. doi: 10.1017/S0007114519002137. [Epub ahead of print]

Enzymatically modified isoquercitrin improves endothelial function in volunteers at risk of cardiovascular disease.

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School of Biomedical Science, University of Western Australia, Royal Perth Hospital, Perth, 6000 Western Australia, Australia.
School of Medical and Health Sciences, Edith Cowan University, Perth, 6027 Western Australia, Australia.
School of Public Health and Curtin Health Innovation Research Institute, Curtin University, Perth, 6102 Western Australia, Australia.
Medical School, University of Western Australia, Perth, 6009 Western Australia, Australia.
Centre for Epidemiology and Biostatistics, School of Public Health, FlindersUniversity of South Australia, Adelaide, 5042 South Australia, Australia.


A higher intake of food rich in flavonoids such as quercetin can reduce the risk of CVD. Enzymatically modified isoquercitrin (EMIQ®) has a bioavailability 17-fold higher than quercetin aglycone and has shown potential CVD moderating effects in animal studies. The present study aimed to determine whether acute ingestion of EMIQ® improves endothelial function, blood pressure (BP) and cognitive function in human volunteers at risk of CVD. Twenty-five participants (twelve males and thirteen females) with at least one CVD risk factor completed this randomised, controlled, crossover study. In a random order, participants were given EMIQ® (2 mg aglycone equivalent)/kg body weight or placebo alongside a standard breakfast meal. Endothelial function, assessed by flow-mediated dilatation (FMD) of the brachial artery was measured before and 1·5 h after intervention. BP, arterial stiffness, cognitive function, BP during cognitive stress and measures of quercetin metabolites, oxidative stress and markers of nitric oxide (NO) production were assessed post-intervention. After adjustment for pre-treatment measurements and treatment order, EMIQ® treatment resulted in a significantly higher FMD response compared with the placebo (1·80 (95 % CI 0·23, 3·37) %; P = 0·025). Plasma concentrations of quercetin metabolites were significantly higher (P < 0·001) after EMIQ® treatment compared with the placebo. No changes in BP, arterial stiffness, cognitive function or biochemical parameters were observed. In this human intervention study, the acute administration of EMIQ® significantly increased circulating quercetin metabolites and improved endothelial function. Further clinical trials are required to assess whether health benefits are associated with long-term EMIQ® consumption.


Blood pressure; Cognitive function; Endothelial function; Enzymatically modified isoquercitrin


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