A randomized, double-blind, placebo-controlled study evaluating the effects of quercetin-rich onions on cognitive function in elderly subjects

Abstract

Background: Quercetin, a phenolic compound, exhibits various functional effects that include anti-oxidant, anti-dyslipidemic, and anti-dysglycemic activities, in addition to beneficial effects on cognitive function. We evaluated the effects of a powder made from quercetin-rich onions (‘Quergold’ and ‘Sarasara-gold’) on cognitive function. Methods: In this randomized, double-blind, placebo-controlled study, we randomized 50 adults (25 males and 25 females, aged 65–84 years) and made them consume products made from quercetin-rich (active test food group) or quercetin-free (placebo food group) onions. Cognitive function, hematological, and biological examinations were performed at the beginning (week 0) of the study and at weeks 12 and 24 after the start of the study. Results: There were no differences in the Mini-Mental State Examination (MMSE) and cognitive impairment rating scale scores between the two groups. However, in younger subjects, the MMSE scores were significantly higher 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 onions improves cognitive function and reduce cognitive decline in elderly people.