A Randomized, Double-Blind, Placebo-Controlled Study Evaluating the Effects of Quercetin-Rich Onion on Cognitive Function in Elderly Subjects

Background: Quercetin, a phenolic compound, has various functional effects, including anti-oxidant, anti-dyslipidaemic and anti-dysglycemic activities, and beneficial effects on cognitive function.Methods: We evaluated the effects of a powder made from quercetin-rich onions (‘Quergold’ and ‘Sarasara-gold’) on cognitive function. In this randomised, double-blind, placebo-controlled study, we randomised 50 adults (25 males and 25 females, aged 65–84 years) to consume products made from quercetin-rich (active) or quercetin-poor (placebo) onions. Cognitive function and haematological and biological examinations were performed at weeks 0, 12 and 24 of the study period.Results: There were no differences in Mini Mental State Examination (MMSE) and cognitive impairment rating scale scores between the two groups. However, in younger subjects, MMSE scores were significantly increased in the active test food group than in the placebo food group at week 24 (p = 0.019).Conclusion: These results suggest that the ingestion of quercetin-rich onion can improve cognitive function and prevent dementia in elderly people.Keywords: clinical trial; cognitive function; mild cognitive impairment; Mini Mental, State Examination; onion; quercetin