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Short-term effects of a Mediterranean-style dietary pattern on cognition and mental wellbeing: A systematic review of clinical trials

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Latife Esgunoglu at University of East Anglia
Latife Esgunoglu
Amy Jennings at University of East Anglia
Amy Jennings
E.S. Connole
E.S. Connole
E.S. Connole
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Karen J Murphy at University of South Australia
Karen J Murphy
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Irish Section Conference, 22–24 June 2021, Nutrition, health and ageing —translating science into practice –Part A
Short-term effects of a Mediterranean-style dietary pattern on cognition
and mental wellbeing: A systematic review of clinical trials
L. Esgunoglu
1
, A. Jennings
1
, E.S. Connole
2
, K.J. Murphy
2
and A.M. Minihane
1
1
Department of Nutrition and Preventive Medicine, Norwich Medical School, University of East Anglia, Norwich, UK
and
2
Department of Nutrition and Dietetics, Clinical and Health Sciences, University of South Australia, Adelaide,
Australia
The long-term benefits of a Mediterranean-style dietary pattern (MDP) on cognitive
(1)
and other mental health outcomes
(2)
has been
consistently reported. However, the short-term efficacy of a MDP on cognition and mental wellbeing is less researched and remains
mostly unknown. Therefore, this systematic review aimed to scrutinise the data from randomised controlled trials (RCT) to investigate
whether a MDP can improve mental health in the short-term. This process also aimed to identify research gaps and provide insights
into the design of future acute RCTs in the area.
Systematic searches were conducted in Ovid Embase, Ovid Medline and Web of Science Core Collection from inception up to
December 2020, with the keywords “Mediterranean diet”,“olive oil”,“cognition”,“dementia”,“mood”,“mood disorders”,“anx-
iety”,“anxiety disorders”,“depression”,“depressive disorders”and “wellbeing”. RCTs conducted in adults (both males and females,
over 18 years), up to and including 10 days intervention were included. No additional exclusion criteria were applied. A quality assess-
ment was done using RoB2, a revised tool for risk of bias by Cochrane. A narrative approach was used to synthesise the data. A
predefined protocol was registered with PROSPERO (CRD42021221085).
In total, 3002 studies were retrieved through initial database searches. Following the elimination of duplicates and screening stages,
4 studies met the inclusion criteria, all of which conducted in non-Mediterranean countries. Three studies included only young females
(18 to 38 years) and one included both genders aged 60 to 80 years. Participants had no previous cognitive and mental health com-
plaints. Despite the limited evidence available and the heterogeneity among the methods, the findings indicate that a MDP improves
cognition and mood in the short-term. In particular, increases after MDPs compared to the controls in attention (1.1-1.4 fold), alert-
ness (_p = _0.003; F= 14.11, p< 0.01; F = 22.23, p < 0.001) and contentment (p= 0.001; F= 6.49, p< 0.02; F= 16.634, p< 0.001) were
consistently reported.
As a novel contribution to the literature, the short-term effects of a MDP on cognition and mood were reviewed systematically for
the first time. A MDP was identified as a promising nutritional strategy to improve cognitive and other mental health outcomes in the
short-term. This is valuable to promote the quality of life, for not only those with existing cognitive and mental health deficits but also
healthy individuals. A recognised significant limitation of this study is the small amount of evidence available to review, however, this
severe limitation has provided a systematic identification of research gaps, with further studies are needed to confirm these initial
findings, and to provide granularity as to which domains are most responsive and in which population subgroups.
References
1. Shannon OM, Stephan BC, Granic A et al. (2019) Am J Clin Nutr 110, 938–948
2. Altun A, Brown H, Szoeke C et al. (2019) Neurol Psychiatry and Brain Res 33,1–10
Proceedings of the Nutrition Society (2021), 80 (OCE3), E151 doi:10.1017/S0029665121002743
Proceedings of the Nutrition Society
. https://doi.org/10.1017/S0029665121002743
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... By contrast, a systematic review of RCTs explored the effects of nutrition on cognition, and the results indicated that the MeDi improved cognitive function but the DASH diet did not (Gutierrez et al., 2021). Notably, in the systematic reviews investigating various or specific dietary patterns (Chen et al., 2019;Esgunoglu et al., 2021;Gauci et al., 2022;Gutierrez et al., 2021), the number of RCTs included was limited, and therefore, only qualitative synthesis was conducted. Of these systematic reviews, some only included English articles (Chen et al., 2019) or evaluated few databases (Gutierrez et al., 2021). ...
... This is possibly because the intervention period was not long enough. Notably, the research indicated that a non-MeDi is not necessarily harmful; the consumption of sufficent quantities of plant foods appears to regulate the structure and function of the gut microbiota (de Filippis et al., 2016;Esgunoglu et al., 2021). ...
Effect of Dietary Patterns on Cognitive Functions of Older Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Article
  • Feb 2023
  • ARCH GERONTOL GERIAT
Background: Dietary patterns are associated with cognitive benefits, but inconsistent findings have been reported concerning this association. This study aims to provide a more comprehensive review and higher evidence level by evaluating evidence from randomized controlled trials (RCTs) exploring effects of various dietary patterns on cognitive function outcomes in older adults. Methods: This systematic review and meta-analysis study followed the PRISMA guidelines. Twelves search engines and databases were searched for papers published up until March 2022. Random-effects models were used to calculate effect size (ES). Results: Twenty-two RCTs met our inclusion criteria. A wide range of cognitive measures were used across the included studies. To reduce heterogeneity and to ensure a sufficient number of studies for meaningful interpretation, we utilized global cognition as the outcome measure. Only nine studies used global cognition measures, including the Mini-Mental State Examination (MMSE), Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), Cognitive Abilities Screening Instrument (CASI), or neuropsychological test battery. Additionally, seven dietary patterns were identified in these studies. The results demonstrated that dietary patterns achieved a significant improvement on cognitive function outcomes including the MMSE/CASI (ES = 0.303; 95% CI [0.045, 0.560]), the ADAS-Cog (ES = -0.277; 95% CI [-0.515, -0.039]), and the cognitive battery (ES = 0.132; 95% CI [0.010, 0.255]). Conclusions: Multidisciplinary health-care professionals may use this information as a reference when planning elder care. More large-scale, high-quality studies are required to explore the long-term effects of healthy dietary patterns on global cognition, other cognitive domains, and life quality among older adults.
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... Moreover, considering the diverse population with different diseases-each having unique pathological mechanisms-makes it more challenging to draw a consensus on how a specific dietary pattern affects a particular condition. In another review [48], the effect of short-term (up to 10 days) MD interventions was assessed in healthy participants or individuals with metabolic syndrome. The review reported data from four RCTs without performing a quantitative synthesis and suggested that MD interventions could improve mood in the short term. ...
Effect of Different Dietary Patterns on Patients with Depressive Disorders: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Article
Full-text available
  • Jan 2025
Objectives: This study aimed to investigate the effects of different dietary patterns on depressive disorders. Methods: PubMed/MEDLINE, Cochrane CENTRAL, Embase, PsycINFO, Scopus, and ProQuest databases were systematically searched until 30 April 2024 for randomized controlled trials (RCTs) assessing the effects of different dietary patterns on depressive symptoms in adults with depressive disorders. Secondary outcomes included remission rates, quality of life, and safety. Standardized mean difference (SMD) and 95% confidence intervals (CIs) were aggregated using a random-effects model. Study quality was assessed with the Cochrane Risk of Bias (RoB)-2 tool, and certainty of evidence was determined using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. Results: Five RCTs (n = 952) were included, all investigating the Mediterranean diet (MD) in individuals with major depressive disorder or elevated depression levels. The analysis found no significant effect of short-term MD intervention on depression severity compared to active (SMD = −1.25 [95% CI: −5.11 to 2.61]) or passive (SMD = −0.22 [95% CI: −0.74 to 0.29]) controls. There was no effect on quality of life compared to active controls (SMD = 0.71 [95% CI = −3.38 to 4.79]). Intermediate and long-term results were similar. The overall risk of bias was “some concerns”, and the certainty of evidence was “very low” for most of the results. Conclusions: The MD appears to have no potential influence on major depressive disorder. However, this finding should be interpreted cautiously due to the limited number of RCTs. Further studies on dietary patterns and depressive disorders are needed for more robust conclusions. Systematic Review Registration: PROSPERO registration no. CRD42024541885.
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... Although research on the effects of diet on psychological health started by examining nutrient deficiencies, the interest continues to increase in eating behavior [23]. A recent meta-analysis revealed that a Mediterranean dietary pattern may positively affect mental health [24]. In addition, a positive association between skipping meals and depression has been reported [25]. ...
The relationship between night eating behavior, gastrointestinal symptoms, and psychological well-being: insights from a cross-sectional study in Türkiye
Article
Full-text available
  • Jan 2025
Background This cross-sectional study aimed to address the gap in understanding how night eating behavior impacts gastrointestinal health and psychological well-being in adult populations. Method This descriptive and cross-sectional study was conducted with 1372 adults aged 19–65 between September 2023 and November 2023. The research data were collected with the help of a web-based survey form (Google form) created by the researchers using the snowball sampling method. The demographic characteristics (sex, age, education level, marital status, income status), eating behaviors (number of main meals and snacks), and anthropometric measurements (body weight and height). Gastrointestinal symptoms observed in individuals were evaluated with the Gastrointestinal Symptom Rating Scale. The Night Eating Questionnaire (NEQ) was used to quantify the severity of night eating syndrome, and The Psychological Well-Being Scale was used to measure psychological well-being. All analyses were performed using the Statistical Package for the Social Sciences (version 27.0) software. Results A statistically significant negative correlation was found between the Psychological Well-Being Scale total score and Gastrointestinal Symptom Rating Scale subdimensions (r=-0.067, r=-0.067, r=-0.109, r=-0.068, r=-0.129, respectively). Also, a statistically significant negative correlation was found between the Psychological Well-Being Scale total score and the Night Eating Questionnaire total score (r=-0.287) (p < 0.05). Conclusion This study found a relationship between night eating syndrome, psychological well-being, and gastrointestinal symptoms. Nutritional strategies for night eating syndrome, an eating disorder, may have important consequences on the psychological well-being of individuals with night eating. Our study highlights the significant relationships between night eating behavior, gastrointestinal symptoms, and psychological well-being, suggesting that night eating may contribute to both physical and mental health challenges.
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... After completing the four SMART modules, training continues with online learning about solutions to minimize stress. These SMART strategies associated with stress management techniques are designed to build a more resilient mindset by integrating stress management techniques with healthy lifestyle choices such as physical exercise, diet, and mindful meditation-practices that have been empirically shown to reduce stress [39][40][41][42][43]. The sleep module provides information on not only the science of sleep and aspects such as sleep cycles, but also walks participants through sleep hygiene tips to help improve their quality and quantity of sleep. ...
The BrainHealth Project Study Protocol: A Longitudinal Study in Generally Healthy Adults
Preprint
Full-text available
  • Aug 2024
Background: Optimization of brain health is a focal point in medical science, yet data regarding measuring, preserving, and improving lifelong brain health are lacking. This void demands an objective, change-sensitive measure of brain health and proven strategies to strengthen brain performance. The BrainHealth Project addresses these key issues, drawing upon neuroplasticity evidence of persistent modifiability of brain function across the lifespan. This landmark study aims to definitively (i) evaluate and refine holistic change indices of brain health, (ii) evaluate the impact of evidenced-based cognitive strategies and lifestyle interventions on improving/maintaining brain health, and (iii) elucidate the mechanisms associated with brain health gains/losses. Methods: This prospective, longitudinal, interventional, open-label, single-arm clinical trial aims to recruit 100,000 generally healthy adults over 10 years. Assessments, coaching, and training are conducted online through the secure BrainHealth Platform, allowing utilization tracking. The BrainHealth Index (BHI)—a multidimensional assessment—is offered at baseline and every six months. Participants have access to coaching every three months and continual access to self-paced trainings and resources. The primary outcome is the further validation of a novel composite BHI score and its sub-scores: Clarity (cognitive health), Connectedness (social health), and Emotional Balance (well-being). The BHI includes measures sensitive to change, including gains from behavior change and integration of cognitive strategies into daily life. These contrast with traditional assessments focused on detecting cognitive decline or diagnosing pathological conditions. The primary online training, SMART (Strategic Memory Advanced Reasoning Tactics), is a strategy-based program validated with 25+ years of research. SMART promotes improvements in neural health, cognition, well-being, connectedness, and real-life function, previously reported in randomized controlled trials (RCTs). Statistical approaches focus on individual prediction using nonlinear models trained with large samples and on assessing mechanisms influencing gains or losses on brain health metrics. Discussion: This research extends RCT evidence to a longitudinal, epidemiologic approach, leveraging digital health and machine learning tools to deliver a generalizable measure of longitudinal brain health and to achieve precision brain health. By integrating advanced statistical methods and large-scale data, the BrainHealth Project should provide medicine and society with accurate and actionable ways to optimize brain health practices across the lifespan. ClinicalTrials.gov Identifier: NCT04869111 (registered April 27, 2021)
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The relationship between the Mediterranean diet and Axis I disorders: A systematic review of observational studies
Article
Full-text available
  • Jun 2022
Abstract Axis I disorders are one of the major health burdens worldwide. Evidence suggests that Mediterranean diet has key biological factors associated with reducing the progression of these disorders. This systematic review aimed to clarify the relationship between Mediterranean diet and Axis I disorders. PubMed and Scopus databases were searched from January 2016 up to June 2021. Those observational studies in English language that assessed the relationship between Mediterranean diet and Axis I disorders (such as depression, anxiety, eating disorders, schizophrenia, etc.) were included in this review. The Newcastle–Ottawa Scale was used to evaluate the quality of studies. Thirty‐six studies (15 cohorts, 19 cross‐sectional, and 2 case–control) met the inclusion criteria. The results revealed that more than two‐thirds of the studies (25 studies, 69.44%) had significant protective relationship between receiving Mediterranean diet and reducing the symptoms or incidence of Axis I disorders. Most studies were performed on depression (29 studies measured depression at least as one of the Axis I disorders), of which 72.41% reported an inverse relationship. There were also 9 studies on anxiety (studies that measured anxiety at least as one of the Axis I disorders), that 77.77% of them observed protective association. Moreover, majority of the studies (25 studies, 69.44%) had high quality, of which 76% found an inverse relationship. In conclusion, it seems that the Mediterranean diet can reduce the symptoms or the occurrence of Axis I disorders (especially depression and anxiety). However, more extensive review studies, particularly with interventional designs, are necessary to prove the result.
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Microbiota-targeted interventions for mental health
Article
Full-text available
  • Nov 2021
Purpose of review: The gut microbiota has emerged as a key conduit in mental health and is a promising target for interventions. This review provides an update on recent advances in using microbiota-targeted approaches for the management of mental health. Recent findings: Approaches that have emerged as microbiota-targeted interventions in the management of mental health include probiotics, prebiotics, synbiotics, fecal microbiota transplant as well as diet. Among these approaches, probiotic supplementation has been investigated most prominently, providing promising evidence for its use in improving mood and anxiety. There is also growing interest in the use of multistrain probiotics, whole dietary interventions or combined approaches, with encouraging results emerging from recent studies. Summary: Although the current literature preliminarily supports targeting the microbiota to manage mental health and use as adjuvant therapies for certain brain disorders, large gaps remain and especially data including clinical cohorts remains scarce. Research studies including larger cohorts, well-characterized clinical populations and defined duration and dosage of the intervention are required to develop evidence-based guidelines for microbiota-targeted strategies.
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Mediterranean diet adherence and cognitive function in older UK adults: The European Prospective Investigation into Cancer and Nutrition-Norfolk (EPIC-Norfolk) Study
Article
Full-text available
  • Jun 2019
  • AM J CLIN NUTR
Background: In Mediterranean countries, adherence to a traditional Mediterranean dietary pattern (MedDiet) is associated with better cognitive function and reduced dementia risk. It is unclear if similar benefits exist in non-Mediterranean regions. Objectives: The aims of this study were to examine associations between MedDiet adherence and cognitive function in an older UK population and to investigate whether associations differed between individuals with high compared with low cardiovascular disease (CVD) risk. Methods: We conducted an analysis in 8009 older individuals with dietary data at Health Check 1 (1993-1997) and cognitive function data at Health Check 3 (2006-2011) of the European Prospective Investigation into Cancer and Nutrition-Norfolk (EPIC-Norfolk). Associations were explored between MedDiet adherence and global and domain-specific cognitive test scores and risk of poor cognitive performance in the entire cohort, and when stratified according to CVD risk status. Results: Higher MedDiet adherence defined by the Pyramid MedDiet score was associated with better global cognition (β ± SE = -0.012 ± 0.002; P < 0.001), verbal episodic memory (β ± SE = -0.009 ± 0.002; P < 0.001), and simple processing speed (β ± SE = -0.002 ± 0.001; P = 0.013). Lower risk of poor verbal episodic memory (OR: 0.784; 95% CI: 0.641, 0.959; P = 0.018), complex processing speed (OR: 0.739; 95% CI: 0.601, 0.907; P = 0.004), and prospective memory (OR: 0.841; 95% CI: 0.724, 0.977; P = 0.023) was also observed for the highest compared with the lowest Pyramid MedDiet tertiles. The effect of a 1-point increase in Pyramid score on global cognitive function was equivalent to 1.7 fewer years of cognitive aging. MedDiet adherence defined by the Mediterranean Diet Adherence Screener (MEDAS) score (mapped through the use of both binary and continuous scoring) showed similar, albeit less consistent, associations. In stratified analyses, associations were evident in individuals at higher CVD risk only (P < 0.05). Conclusions: Higher adherence to the MedDiet is associated with better cognitive function and lower risk of poor cognition in older UK adults. This evidence underpins the development of interventions to enhance MedDiet adherence, particularly in individuals at higher CVD risk, aiming to reduce the risk of age-related cognitive decline in non-Mediterranean populations.
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The Mediterranean dietary pattern and depression risk: A systematic review
Article
  • Sep 2019
  • NEUROL PSYCHIAT BR
Background Depression is a major global health burden and psychiatry requires evidence-based primary prevention and treatment strategies. Evidence suggests that certain dietary patterns, in particular, components of the Mediterranean diet, possess key biological factors associated with abating depressive risk and disease progression. We sought to evaluate the existing evidence regarding the association between the Mediterranean diet and depressive symptoms by conducting a systematic review. Methods A search of published studies was conducted using the computer databases Medline, Embase, PsychINFO, Scopus and Google Scholar, for articles in the English language published from inception to April 2018. The search strategy applied the following subject headings and keywords: “Mediterranean diet” OR Mediterranean* AND “Major depressive disorder” OR Depress* OR “Negative mood” OR Mood. The NIH quality assessment tool was implemented by reviewers to determine study quality. Results Results from twenty observational studies and six intervention trials were qualitatively examined. The majority (85%) of observational studies support the evidence that the Mediterranean dietary pattern is associated with reductions in depressive incidence and all intervention studies echoed these findings. Limitations Methodological disparity in Mediterranean style diets limited comparisons but were overcome by specifying inclusion criteria and compressive appraisal of the data. Conclusions Modifying diet provides a potential treatment for depression which procures few side effects, lessens disease progression and demonstrates a cost-effective measure that can be implemented globally. Present research has found that more objective measures are necessary to define the Mediterranean diet and highlights the need for longitudinal studies and clinical trials for future research.
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  • Jan 2019
  • AM J CLIN NUTR
  • 938-948
  • O M Shannon
  • B C Stephan
  • A Granic
Shannon OM, Stephan BC, Granic A et al. (2019) Am J Clin Nutr 110, 938-948
  • Jan 2019
  • 1-10
  • A Altun
  • H Brown
  • C Szoeke
Altun A, Brown H, Szoeke C et al. (2019) Neurol Psychiatry and Brain Res 33, 1-10