Abstract/Summary

Context: Collective evidence highlights that diet has a strong interplay with mood and mental health. Diet is of interest from a public health perspective as an easily adoptable lifestyle approach for improving mental health in the general population. Bioactive constituents of diet which have been identified for effects on mental health are flavonoids. Objective: The aim of this review was to evaluate the effects of flavonoids from the diet on mental health, in healthy populations throughout the lifespan. Data sources: Experimental human trials with any age, gender or ethnicity were eligible for inclusion if they supplemented with at least one flavonoid rich food (containing <15mg per 100g/ml of flavonoid constituents) either as lyophilized powder or whole food and measured at least one mood outcome. The electronic databases PubMed, Web of Science and Scopus with no restriction on publication start date to October 2024 and the Evidence Analysis Manual Quality Criteria Checklist (QCC) from the Academy of Nutrition and Dietetics Evidence Analysis Library® was checked for quality of methodology and risk of bias. Data extraction: A total of 38 experimental studies met the eligibility criteria, of these studies, 13 explored the effects of flavonoids in an acute setting, and 25 studies utilised a chronic design. Data analysis: The included studies explored a range of flavonoid containing foods with a majority (n=9) utilising cocoa as an intervention vehicle. Five out of the 13 acute studies reported benefits (utilising 3 wild blueberry, 1 purple grape juice, 1 orange juice); alongside, 12 out of 25 chronic studies showing findings in favour of flavonoid supplementation (2 cocoa, 2 blueberry, 2 cherry, 1 peppermint, 1 orange juice, 1 walnut, 1 green tea, 2 studies using a range of foods), suggesting chronic flavonoid supplementation may be beneficial for mood and mental health outcomes. Conclusions: Further studies are required to understand the effects of flavonoids from the diet utilising consistent methodology and dosing as well as exploring mechanistic links of flavonoids and mental health across the lifespan.