Effect of quercetin glycosides on cognitive functions and cerebral blood flow: a randomized, double-blind, and placebo-controlled study

Y. Nakamura, H. Watanabe, A. Tanaka, J. Nishihira, N. Murayama

Suntory Global Innovation Center Ltd. Research Institute, Kyoto, Japan. Yumi_Nakamura@suntory.co.jp

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• Neurology
• Nutrition

OBJECTIVE: This study aimed to examine the effects of quercetin glycoside-containing beverages on cognitive function and cerebral blood flow (CBF) in adult men and women aged between 60 and 75 years.

PATIENTS AND METHODS: Eighty healthy men and women with no cognitive impairment and aware of ageing-related forgetfulness underwent a placebo-controlled, randomized, double-blind, and parallel-group trial. They regularly consumed 500 mL of beverage containing 110 mg of quercetin glycoside as isoquercitrin for 40 weeks. Cognitive function assessment by Cognitrax was the endpoint of the study. The participants were assessed for CBF, health-related quality of life, as well as physical, biological, and hematological parameters, and lateral index.

RESULTS: Cognitrax demonstrated that the reaction time significantly improved in the quercetin glycoside intake group. The CBF measurement suggested that quercetin glycoside intake could likely suppress the decrease in cerebral blood volume, CBF, and cerebral activity owing to stress alleviation and inhibition of the accumulation of amyloid β (Aβ), a waste product in the brain, although there were no significant differences between the groups.

CONCLUSIONS: Quercetin glycoside intake as a beverage could improve reaction time and may potentially inhibit the decrease in CBF and suppress Aβ accumulation.

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