New evidence suggests that regularly consuming flavonoid-rich foods, such as berries, citrus, cocoa, and tea, may gently improve mood by supporting brain chemistry and neuroplasticity, offering an accessible dietary strategy for everyday emotional resilience.
Study: Effects of Dietary Flavonoids on Mood and Mental Health: A Systematic Review. Image Credit: sav_an_dreas / Shutterstock
In a recent study published in the journal Nutrition Reviews, researchers at the University of Reading, UK, evaluated how dietary flavonoids from commonly consumed foods and beverages affect mood and mental health across the lifespan in physically healthy people.
Global Mental Health Burden and Dietary Context
Since the COVID-19 pandemic, global cases of major depressive disorder and anxiety disorder have risen substantially, and families notice these changes around meals, commutes, and screens. Daily food choices matter, as foods like fruits, cocoa, teas, citrus, and berries supply flavonoids that cross the blood-brain barrier and may influence neurotransmitters and neuroplasticity. Food-based strategies are accessible and familiar, making them easily integrated into daily routines at school, work, and home. However, study results are inconsistent, with varying doses and methods, so clearer evidence is needed to identify what truly helps.
Systematic Review Framework and Eligibility Criteria
This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guideline and was registered on the International Prospective Register of Systematic Reviews. Eligibility was guided by the Population, Intervention, Comparator, Outcome, and Study design framework. Experimental human trials of any age, sex, or ethnicity were included when at least one flavonoid-rich food containing at least fifteen milligrams per one hundred grams or milliliters was provided as whole food or lyophilized powder, and at least one mood or mental health outcome was assessed. Trials using flavonoid extracts, alcohol confounds such as red wine, or clinical conditions influencing physical health or hormone balance were excluded to focus on physically healthy populations.
Search Strategy and Assessment of Methodological Quality
Searches spanned PubMed, Web of Science Core Collection, and Scopus to October 2024. The United States Department of Agriculture and Phenol Explorer databases were used to estimate flavonoid dose when not reported. The risk of bias and methodological quality were assessed using the Quality Criteria Checklist from the Academy of Nutrition and Dietetics Evidence Analysis Library, and data extraction was conducted according to the Library’s standardized template. Mood was defined as emotional and psychological well-being, excluding social belonging and task fatigue. Parallel and crossover trials were eligible without restrictions on duration or blinding.
Intervention Types and Mood Assessment Measures
A total of 38 experimental datasets, involving 1,972 participants, met the criteria. Interventions included wild blueberries, mixed berries, purple grape juice, orange juice, cocoa or dark chocolate, green tea, peppermint, nuts, soy, and apples, with cocoa and wild blueberries being the most studied. Chronic trial durations ranged from five days to twelve months. Mood outcomes were assessed using the Positive and Negative Affect Schedule, Profile of Mood States, State Trait Anxiety Inventory, Bond-Lader visual analogue scales, Beck Depression Inventory, Patient Health Questionnaire 9, Generalized Anxiety Disorder 7, Snaith-Hamilton Pleasure Scale, and Perceived Stress Scale 10.
Evidence on Short-Term Flavonoid Effects on Mood
Acute effects were mixed. Five of the thirteen studies reported benefits, particularly with anthocyanin-rich foods. Three acute wild blueberry datasets showed an increase in Positive Affect in children, young adults, and emerging adults. Purple grape juice elevated calmness, and an orange juice study indicated favorable short-term mood effects. Several cocoa-based acute trials showed no change, suggesting that dose, food matrix, or expectancy may influence the detection of the impact. Overall, acute responses appear to be possible but inconsistent across different foods and time points.
Findings from Chronic Flavonoid Supplementation Trials
Chronic findings were more encouraging. Twelve of twenty-five studies favored flavonoid supplementation, including wild blueberry for depressive symptoms in adolescents, cherry for anxiety and alertness, cocoa for lower negative affect in select designs, as well as peppermint, orange juice, walnuts during exam stress, green tea, and multi-food patterns. Benefits were most common in anthocyanin-rich choices consumed daily over weeks. Null results were also reported, indicating that population factors, baseline diet, dose ranging from 30 to 774 milligrams of anthocyanins per day, duration of at least three to four weeks, and outcome tool selection shape the observed results.
Methodological Quality and Biological Mechanisms
Methodological quality varied. Eight studies were rated as positive, three were rated as negative, and the majority were neutral. Common weaknesses included insufficient reporting of withdrawals, unclear randomization, and heterogeneity in dosing and measurement timing. Biological plausibility is supported by known mechanisms. Flavonoids can cross the blood-brain barrier, act as monoamine oxidase inhibitors, influencing the levels of serotonin, dopamine, and noradrenaline, and modulate brain-derived neurotrophic factor, a key driver of neuroplasticity.
Observational and Real World Implications
Observational data, including analyses from the National Health and Nutrition Examination Survey, link anthocyanidin intake with lower prevalence of depression. Meanwhile, intervention studies show that a diet combined with activity programs can improve well-being. These signals align with the idea that habitual food-based flavonoid intake may support mood. For daily life, this translates to making repeated choices, such as adding berries to breakfast, swapping a sugary snack for citrus, or opting for high-cocoa dark chocolate in mindful portions. These strategies may be particularly helpful during exam stress or acute mental stress, when timing and cognitive load can significantly influence outcomes.
Interpretation and Needed Research Directions
To summarize, in physically healthy populations, dietary flavonoids exhibit promising yet heterogeneous benefits for mood, with stronger evidence from chronic interventions rich in anthocyanins. Effects are modest and context-dependent, but align with plausible neurobiological pathways, including monoamine oxidase inhibition and brain-derived neurotrophic factor support. Food-based strategies are accessible and fit budgets and habits, potentially easing stress and low mood over weeks. More straightforward dosing guidelines, standardized outcomes, and more diverse samples are needed to guide practice and policy.
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