Effects of Dietary Flavonoids on Mood and Mental Health: A Systematic Review

CONTEXT: Collective evidence has highlighted the strong interplay of the diet with mood and mental health. The diet is a topic of interest from a public health perspective as it may provide an adoptable lifestyle approach for improving mental health in the population. Among dietary constituents, flavonoids have been identified as particularly relevant for mental health.

OBJECTIVE: The aim of this review was to evaluate the effects of dietary flavonoids on mental health in healthy populations across the lifespan.

DATA SOURCES: Experimental human trials with study participants of any age, sex, or ethnicity were eligible for inclusion in this review if they included supplementation with at least 1 flavonoid-rich food (<15 mg/100 g/mL flavonoid constituents) either as lyophilized powder or whole food and measured at least 1 mood outcome. The PubMed, Web of Science, and Scopus databases were searched with no restriction on publication start date to October 2024. The Evidence Analysis Manual Quality Criteria Checklist (QCC) from the Academy of Nutrition and Dietetics Evidence Analysis Library(R) was used to assess methodology and risk of bias.

DATA EXTRACTION: A total of 38 experimental studies met eligibility criteria, 13 exploring acute effects of flavonoids and 25 utilising a chronic design.

DATA ANALYSIS: The included studies explored a range of flavonoid-containing foods, with a majority (n = 9) utilizing cocoa as an intervention vehicle. Five of the 13 acute studies reported benefits (3 wild blueberry, 1 purple grape juice, 1 orange juice); and 12 of 25 chronic studies showed findings in favor of flavonoid supplementation (2 cocoa, 2 blueberry, 2 cherry, 1 peppermint, 1 orange juice, 1 walnut, 1 green tea, and 2 mixed foods), suggesting chronic supplementation may benefit mood and mental health.

CONCLUSIONS: Further studies are required to understand the effects of dietary flavonoids utilizing consistent methodology and dosing, as well as to explore mechanistic links with mental health across the lifespan.

SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration No. [CRD42021293040].