Diet and Depression-From Confirmation to Implementation

The Role of Gut Microbiota, Nutrition, and Physical Activity in Depression and Obesity-Interdependent Mechanisms/Co-Occurrence

Obesity and depression are interdependent pathological disorders with strong inflammatory effects commonly found worldwide. They determine the health status of the population and cause key problems in terms of morbidity and mortality. The role of gut microbiota and its composition in the treatment of obesity and psychological factors is increasingly emphasized. Published research suggests that prebiotic, probiotic, or symbiotic preparations can effectively intervene in obesity treatment and mood-dysregulation alleviation. Thus, this literature review aims to highlight the role of intestinal microbiota in treating depression and obesity. An additional purpose is to indicate probiotics, including psychobiotics and prebiotics, potentially beneficial in supporting the treatment of these two diseases.

Efficacy and Safety of Antidiabetic Agents for Major Depressive Disorder and Bipolar Depression: A Meta-Analysis of Randomized, Double-Blind, Placebo-Controlled Trials

BACKGROUND

This meta-analysis aimed to determine the efficacy and safety of antidiabetic agents in the treatment of major depressive disorder and bipolar depression.

METHODS

Randomized controlled trials (RCTs) of antidiabetic agents in major depressive disorder or bipolar depression were searched in three electronic databases and three clinical trial registry websites from their inception up to October 2023. The differences in changes in the depression rating scale scores from baseline to endpoint or pre-defined sessions, response rate, remission rate, rate of side effects and dropout rate between antidiabetic agents and placebo were meta-analyzed.

RESULTS

Six RCTs involving 399 participants were included in the final meta-analysis, which did not find that antidiabetics outperformed the placebo in reducing depressive symptoms. The standardized mean difference (SMD) in the depression scores from baseline to endpoint was 0.25 (95% CI -0.1, 0.61). However, a subgroup analysis found a significant difference between antidiabetics and placebos in reducing depressive symptoms in Middle Eastern populations, with an SMD of 0.89 (95% CI 0.44, 1.34).

CONCLUSIONS

The current meta-analysis does not support the efficacy of antidiabetics being superior to the placebo in the treatment of unipolar and bipolar depression. However, a subgroup analysis indicates that patients from the Middle East may benefit from adding an antidiabetic medication to their ongoing medication(s) for their depression. Larger studies with good-quality study designs are warranted.

The engagement of psychology with complementary medicine: A critical integrative review

Amidst the global rise in complementary medicine (CM) use for mental health, a substantial number of clients consulting a psychologist also utilise at least one form of CM. Yet, how psychologists should engage with CM in their clinical practice (e.g., how to respond to a client disclosing CM use or enquiries regarding CM products or services for mental health) remains contested and unclear. In response, a systematic integrative review was conducted to examine empirical literature reporting on one or more aspects of the relationship between psychology (incorporating clinical practice, professional associations and academia) and CM, and how that relationship may relate to or inform psychologists' engagement with CM in their clinical practice. Twenty-seven peer-reviewed articles met the specific inclusion criteria and quality appraisal was employed. Analysis shows a substantial number of psychologists are engaging with, or are interested in engaging with, CM in their clinical practice. Analysis identified a dissonance between psychologists' engagement with CM in clinical practice and the limited engagement of the broader discipline of psychology with CM. Further research is required to understand these differing types of engagement with a view to helping inform relevant policy and practice guidelines, and ultimately assist psychologists in navigating CM in their clinical practice.

The Association between Vegan, Vegetarian, and Omnivore Diet Quality and Depressive Symptoms in Adults: A Cross-Sectional Study

Dietary patterns and depressive symptoms are associated in cross-sectional and prospective-designed research. However, limited research has considered depression risk related to meat-based and plant-based dietary patterns. This study explores the association between diet quality and depressive symptoms across omnivore, vegan, and vegetarian dietary patterns. A cross-sectional online survey utilised the Dietary Screening Tool (DST) and the Centre for Epidemiological Studies of Depression Scale (CESD-20) to measure diet quality and depressive symptoms, respectively. A total of 496 participants identified as either omnivores (n = 129), vegetarians (n = 151), or vegans (n = 216). ANOVA with Bonferroni post hoc corrections indicates that dietary quality was significantly different between groups F(2, 493) = 23.61, p < 0.001 for omnivores and vegetarians and omnivores and vegans. Diet quality was highest in the vegan sample, followed by vegetarian and omnivore patterns. The results show a significant, moderately negative relationship between higher diet quality and lower depressive symptoms (r = -0.385, p < 0.001) across groups. Hierarchical regression showed that diet quality accounted for 13% of the variability in depressive symptoms for the omnivore sample, 6% for vegetarians, and 8% for vegans. This study suggests that diet quality in a meat-based or plant-based diet could be a modifiable lifestyle factor with the potential to reduce the risk of depressive symptoms. The study indicates a greater protective role of a high-quality plant-based diet and lower depressive symptoms. Further intervention research is needed to understand the bi-directional relationship between diet quality and depressive symptoms across dietary patterns.

Dietary interventions, the gut microbiome, and aggressive behavior: Review of research evidence and potential next steps

Research in biosocial criminology and other related disciplines has established links between nutrition and aggressive behavior. In addition to observational studies, randomized trials of nutritional supplements like vitamins, omega-3 fatty acids, and folic acid provide evidence of the dietary impact on aggression. However, the exact mechanism of the diet-aggression link is not well understood. The current article proposes that the gut microbiome plays an important role in the process, with the microbiota-gut-brain axis serving as such a mediating mechanism between diet and behavior. Based on animal and human studies, this review synthesizes a wide array of research across several academic fields: from the effects of dietary interventions on aggression, to the results of microbiota transplantation on socioemotional and behavioral outcomes, to the connections between early adversity, stress, microbiome, and aggression. Possibilities for integrating the microbiotic perspective with the more traditional, sociologically oriented theories in criminology are discussed, using social disorganization and self-control theories as examples. To extend the existing lines of research further, the article considers harnessing the experimental potential of noninvasive and low-cost dietary interventions to help establish the causal impact of the gut microbiome on aggressive behavior, while adhering to the high ethical standards and modern research requirements. Implications of this research for criminal justice policy and practice are essential: not only can it help determine whether the improved gut microbiome functioning moderates aggressive and violent behavior but also provide ways to prevent and reduce such behavior, alone or in combination with other crime prevention programs.

Can Following Paleolithic and Mediterranean Diets Reduce the Risk of Stress, Anxiety, and Depression: A Cross-Sectional Study on Iranian Women

Background

Psychiatric disorders have been a challenge for public health and will bring economic problems to individuals and healthcare systems in the future. One of the important factors that could affect these disorders is diet.

Objective

In the current study with a cross-sectional design, we investigated the association of Paleolithic and Mediterranean diets with psychological disorders in a sample of adult women.

Methods

Participants were 435 adult women between 20 and 50 years old that refer to healthcare centers in the south of Tehran, Iran. The diet scores were created by the response to a valid and reliable semiquantitative food frequency questionnaire (FFQ), and the psychological profile was determined by response to the Depression, Anxiety, and Stress Scale (DASS-21). The multivariable-adjusted logistic regression was applied to compute the odds ratio (OR) and 95% confidence interval (CI).

Results

After adjusted for potential confounders, it is evident that participants in the highest Paleolithic diet tertile had lower odds of depression (OR = 0.21; 95% CI: 0.12, 0.37: P < 0.001), anxiety (OR = 0.27; 95% CI: 0.16, 0.45: P < 0.001), and stress (OR = 0.19; 95% CI: 0.11, 0.32; P < 0.001) in comparison to the lowest tertile. Furthermore, those in the third tertile of the Mediterranean diet score were at lower risk of depression (OR = 0.20; 95% CI: 0.11, 0.36; P < 0.001), anxiety (OR = 0.22; 95% CI: 0.13, 0.38; P < 0.001), and stress (OR = 0.23; 95% CI: 0.13, 0.39; P < 0.001) compared with those in the first tertile.

Conclusion

The result of the current study suggests that greater adherence to Paleolithic and Mediterranean dietary patterns may be related with a decreased risk of psychological disorders such as depression, anxiety, and stress.

Nutrition and mental health: A review of current knowledge about the impact of diet on mental health

Applied psychopharmacotherapy and psychotherapy do not always bring the expected results in the treatment of mental disorders. As a result, other interventions are receiving increasing attention. In recent years, there has been a surge in research on the effects of nutrition on mental status, which may be an important aspect of the prevention of many mental disorders and, at the same time, may lead to a reduction in the proportion of people with mental disorders. This review aims to answer whether and to what extent lifestyle and related nutrition affect mental health and whether there is scientific evidence supporting a link between diet and mental health. A review of the scientific evidence was conducted based on the available literature by typing in phrases related to nutrition and mental health using the methodological tool of the PubMed database. The literature search yielded 3,473 records, from which 356 sources directly related to the topic of the study were selected, and then those with the highest scientific value were selected according to bibliometric impact factors. In the context of current changes, urbanization, globalization, including the food industry, and changes in people’s lifestyles and eating habits, the correlations between these phenomena and their impact on mental state become important. Knowledge of these correlations creates potential opportunities to implement new effective dietary, pharmacological, therapeutic, and above all preventive interventions. The highest therapeutic potential is seen in the rational diet, physical activity, use of psychobiotics, and consumption of antioxidants. Research also shows that there are nutritional interventions that have psychoprotective potential.

Role of diet and its effects on the gut microbiome in the pathophysiology of mental disorders

There is emerging evidence that diet has a major modulatory influence on brain-gut-microbiome (BGM) interactions with important implications for brain health, and for several brain disorders. The BGM system is made up of neuroendocrine, neural, and immune communication channels which establish a network of bidirectional interactions between the brain, the gut and its microbiome. Diet not only plays a crucial role in shaping the gut microbiome, but it can modulate structure and function of the brain through these communication channels. In this review, we summarize the evidence available from preclinical and clinical studies on the influence of dietary habits and interventions on a selected group of psychiatric and neurologic disorders including depression, cognitive decline, Parkinson's disease, autism spectrum disorder and epilepsy. We will particularly address the role of diet-induced microbiome changes which have been implicated in these effects, and some of which are shared between different brain disorders. While the majority of these findings have been demonstrated in preclinical and in cross-sectional, epidemiological studies, to date there is insufficient evidence from mechanistic human studies to make conclusions about causality between a specific diet and microbially mediated brain function. Many of the dietary benefits on microbiome and brain health have been attributed to anti-inflammatory effects mediated by the microbial metabolites of dietary fiber and polyphenols. The new attention given to dietary factors in brain disorders has the potential to improve treatment outcomes with currently available pharmacological and non-pharmacological therapies.

Adjunctive dietary intervention for bipolar disorder: a randomized, controlled, parallel-group, modified double-blinded trial of a high n-3 plus low n-6 diet

OBJECTIVE

To investigate the preliminary efficacy of a high n-3 plus low n-6 (H3-L6) dietary intervention in improving mood stability in Bipolar Disorder (BD) when compared to dietary intervention with usual U.S. levels of n-6 and n-3 polyunsaturated fatty acid (PUFA) intakes (control diet, CD).

METHODS

This 2-arm, parallel-group, randomized, modified double-blind, controlled 48-week study of 12-week intensive diet intervention in subjects with BD was conducted at a single suburban-rural site in the mid-Atlantic region. Participants with DSM-IV TR BD I or II with hypomanic or depressive symptoms were randomized, stratified on gender (N = 82). The intervention included the provision of group-specific study foods and dietary counseling. Variability of mood symptoms was measured by a twice-daily, 12-week ecological momentary analysis (EMA) paradigm, and group differences were analyzed using multilevel models. Circulating n-3 and n-6 fatty acids were measured at baseline and after 4, 8, and 12 weeks of diet exposure.

RESULTS

All 82 randomized participants were included in biochemical analyses. Seventy participants completed at least 2 EMA surveys and were included in primary EMA analyses. Variability in mood, energy, irritability, and pain as measured using EMA was reduced in the H3-L6 group compared to the CD group. No significant differences in mean ratings of mood symptoms, or any other symptom measures, were detected. The dietary intervention effect on target PUFAs significantly differed by the group over time.

CONCLUSIONS

A dietary intervention adjunctive to usual care showed preliminary efficacy in improving variability in mood symptoms in participants with BD.

TRIAL REGISTRATION

ClinicalTrials.Gov NCT02272010.

Processed meat consumption and the risk of incident late-onset depression: a 12-year follow-up of the Salus in Apulia Study

BACKGROUND

the possible relationship between dietary habits and the incidence of late-onset depression (LOD), defined as first depression onset at later age, is unclear.

OBJECTIVE

to investigate the relationship between consumption of different food groups and incident LOD.

DESIGN

longitudinal population-based study with a 12-year follow-up.

SETTING

Castellana Grotte, Bari, Italy.

SUBJECTS

five hundred and forty-six older subjects from the Salus in Apulia Study.

METHODS

baseline data were recorded in 2003-06, and diagnostic data were recorded in 2013-18 at follow-up. Dietary intake was assessed with a food frequency questionnaire. Depressive disorders were assessed with the Structured Clinical Interview for DSM-IV Axis I Disorders. Subjects who already suffered from depression or other psychiatric disorders at baseline were excluded from the analysis. The association between LOD and single dietary determinants was examined by Cox regression analysis and then applying the hazard ratio (HR).

RESULTS

subjects with incident LOD (n = 34) had lower global cognition and total cholesterol levels and a higher body mass index (BMI) at baseline. Only processed meat significantly increased the risk of incident LOD of about 10% by 5 g/day intake (HR adjusted for age, sex, education, multimorbidity and BMI: 1.13, 95% confidence intervals: 1.04-1.22). A similar relationship was found for single foods in the processed meat food group such as sausages, salami and mortadella and baked ham, but not for raw ham.

CONCLUSIONS

in midlife, a higher intake of processed meat was not only associated with an increased risk of cardiovascular- and metabolic-related chronic diseases in older age but also with an increased risk of developing LOD.

Dietary intake of persons with depressive and psychotic disorders in Singapore

INTRODUCTION

Nutritional psychiatry is an emerging field of study that investigates the role of diet and nutrition in mental health. Studies conducted in the general population have linked depressive symptoms with poor dietary patterns. The aim of this study was to characterise the dietary intake and analyse the dietary pattern using the Dietary Approach to Stop Hypertension (DASH) in a sample of psychiatric patients in a multiethnic Asian nation.

METHODS

Participants were recruited from an outpatient clinic and an inpatient unit at the Institute of Mental Health in Singapore. Self-reported dietary habits of a sample of psychiatric patients (N=380) were analysed using DASH. To examine the variables associated with DASH scores, a linear regression was conducted with the full sample and sociodemographic variables.

RESULTS

Persons with depressive disorders had a mean DASH score of 21.3 (±4.2), while persons with psychotic disorders had a mean DASH score of 21.2 (±4.9). Respondents who were older (B=1.94, 95% confidence interval [CI] 0.91-2.96, P<0.001), female (B=1.09, 95% CI 0.07-2.11, P=0.04) and economically inactive (B=1.98, 95% CI 0.006-3.96, P=0.049) were more likely to report a higher diet quality compared with their respective counterparts, while smokers (B= -1.39, 95% CI -2.45 to -0.34, P=0.009) tended to report a lower diet quality compared with their non-smoking counterparts.

CONCLUSION

Dietary patterns of persons with mental disorders were characterised. A host of sociodemographic factors, and not diagnosis of mental disorders, influenced the dietary quality of people with depressive and psychotic disorders. Clinicians treating psychiatric patients need to be aware of the nuanced reasons behind poor dietary choices and provide targeted psychoeducation to specific subgroups within the patient population.

Dietary fiber deficiency as a component of malnutrition associated with psychological alterations in alcohol use disorder

BACKGROUND & AIMS

Chronic alcohol consumption can cause malnutrition that may contribute to alcohol-induced organ injury and psychological disorders. We evaluated the link between nutrient intake, especially dietary fibers (DF) and different parameters reflecting mental health and well being, namely anxiety, depression, alcohol craving, sociability, fatigue and intestinal comfort in alcohol use disorder (AUD) patients.

METHODS

Cross-sectional data from 50 AUD patients, hospitalized for a 3-week detoxification program were used. Three 24-h recalls allowed to calculate dietary habits and nutrient intakes, that was also assessed in healthy subjects (HS). Diet quality was measured using the NOVA score. Psychological factors and intestinal discomfort were evaluated using validated self-administered questionnaires.

RESULTS

Energy intake (excluding alcoholic beverage), total fat, monounsaturated and polyunsaturated fatty acids, protein and DF intakes were lower in AUD subjects compared to HS. Ninety percent of patients had a DF intake below the recommendation. AUD patients consumed more than twice as much ultra-processed food than HS. Fructan intake was negatively associated with anxiety (p = 0.04) adjusted for main confounders. Total DF, insoluble, soluble DF and galacto-oligosaccharide intakes were associated with higher sociability score. Soluble DF intake was associated with better satisfaction of bowel function (p = 0.02) and a lower intestinal discomfort (p = 0.04).

CONCLUSIONS

This study reveals that insufficient DF intake is part of AUD-related malnutrition syndrome, and is associated with higher anxiety, lower sociability score and intestinal discomfort. Our results suggest that an adequate intake of DF might be beneficial for recovery from AUD.

TRIAL REGISTRATION

NCT03803709, https://clinicaltrials.gov/ct2/show/NCT03803709.

Association of Child and Adolescent Mental Health With Adolescent Health Behaviors in the UK Millennium Cohort

Importance

There is potential for mental health status to act as a determinant of an individual's ability to engage in healthful lifestyle behaviors.

Objective

To investigate the associations of parent-reported mental health problems during childhood and self-reported mental health problems in adolescence with health behaviors in adolescence.

Design, Setting, and Participants

This cohort study used data from wave 4 (collected in 2008) and wave 6 (collected in 2015) of the Millennium Cohort Study, a UK population-representative longitudinal study of young people born during 2000 to 2001. Wave 4 included data on parent-reported mental health issues for children at age 7 years. Wave 6 included data on self-reported mental health problems as well as health behaviors for the same children at age 14 years. Data were analyzed July 5, 2020.

Exposures

Mental health problems at age 7 years were parent-reported using Strengths and Difficulties Questionnaire. Mental health problems at age 14 years were self-reported using the Short Mood and Feelings Questionnaire.

Main Outcomes and Measures

Health behaviors at age 14 years were the main outcome of interest. Sleep duration; fruit, vegetable, and soft drink consumption; and social media use were self-reported using recall on a typical day. Regression models were calculated for each lifestyle variable, with mental health change from ages 7 to 14 years as the exposure variable. Data were weighted to account for the potential clustering of region of sampling and adjusted for nonresponse.

Results

A total of 9369 participants were included in waves 4 and 6 of the Millennium Cohort Study, including 4665 (48.1%) girls and 6014 participants (81.9%) who were born in England. Adolescents who self-reported mental health problems at age 14 years only were less likely to have at least 9 hours of sleep (odds ratio [OR], 0.39; 95% CI, 0.34-0.45) and to consume fruit (OR, 0.55; 95% CI, 0.46-0.65) and vegetables (OR, 0.66; 95% CI, 0.52-0.83) reported greater use of social media (b = 0.62; 95% CI, 0.49-0.75) compared with individuals who did not have mental health problems at both time points. Similarly, those with mental health problems at both time points were less likely to achieve 9 hours sleep (OR, 0.68; 95% CI, 0.51-0.90), consume fruit (OR, 0.39; 95% CI, 0.26-0.58) and vegetables (OR, 0.57; 95% CI, 0.35-0.91), and reported greater social media use (b = 0.63; 95% CI, 0.34-0.91).

Conclusions and Relevance

These findings suggest that the presence of depressive symptoms at ages 7 and 14 years and at age 14 years only were associated with some health behaviors in adolescence. These findings are particularly important given that independent health behaviors can deteriorate and become habitual during adolescence, and adolescence is a known time for the first emergence of mental health problems that continue into adulthood.

Depression in the medically ill

BACKGROUND

Depressive disorders are significantly more common in the medically ill compared to the general population. Depression is associated with worsening of physical symptoms, greater healthcare utilization and poorer treatment adherence. The present paper provides a critical review on the assessment and management of depression in the medically ill.

METHODS

Relevant articles pertaining to depression in the medically ill were identified, reviewed and synthesized qualitatively. A systematic review was not performed due to the large breadth of this topic, making a meaningful summary of all published and unpublished studies not feasible. Notable studies were reviewed and synthesized by a diverse set of experts to provide a balanced summary.

RESULTS

Depression is frequently under-recognized in medical settings. Differential diagnoses include delirium, personality disorders and depressive disorders secondary to substances, medications or another medical condition. Depressive symptoms in the context of an adjustment disorder should be initially managed by supportive psychological approaches. Once a mild to moderate major depressive episode is identified, a stepped care approach should be implemented, starting with general psychoeducation, psychosocial interventions and ongoing monitoring. For moderate to severe symptoms, or mild symptoms that are not responding to low-intensity interventions, the use of antidepressants or higher intensity psychotherapeutic interventions should be considered. Psychotherapeutic interventions have demonstrated benefits with small to moderate effect sizes. Antidepressant medications have also demonstrated benefits with moderate effect sizes; however, special caution is needed in evaluating side effects, drug-drug interactions as well as dose adjustments due to impairment in hepatic metabolism and/or renal clearance. Novel interventions for the treatment of depression and other illness-related psychological symptoms (e.g. death anxiety, loss of dignity) are under investigation.

LIMITATIONS

Non-systematic review of the literature.

CONCLUSION

Replicated evidence has demonstrated a bidirectional interaction between depression and medical illness. Screening and stepped care using pharmacological and non-pharmacological interventions is merited.

Breast Cancer: Lifestyle, the Human Gut Microbiota/Microbiome, and Survivorship

Patients with a current diagnosis of breast cancer are enjoying dramatic cure rates and survivorship secondary to an increase in awareness, earlier detection, and more effective therapies. Although strategies such as Breast Cancer Awareness Month in October focus on early detection, lifestyle changes are seldom discussed other than dietary concerns and physical activity. Lifestyle modifications centered on diet and exercise have been demonstrated to affect overall disease-free survival in breast cancer. Since the early 2000s, the role of the human gut microbiota and its relation to breast cancer has become a major area of interest in the scientific and medical community. We live and survive owing to the symbiotic relationship with the microorganisms within us: the human microbiota. Scientific advances have identified a subset of the gut microbiota: the estrobolome, those bacteria that have the genetic capability to metabolize estrogen, which plays a key role in most breast cancers. Recent research provides evidence that the gut microbiome plays a substantial role in estrogen regulation. Gut microbiota diversity appears to be an essential component of overall health, including breast health. Future research attention should include a more extensive focus on the role of the human gut microbiota in breast cancer.

Nutritional Psychiatry: From Concept to the Clinic

The field of 'nutritional psychiatry' has evolved with rapidity over the past several years, with an increasing amount of dietary or nutrient-based (nutraceutical) intervention studies being initiated, and more preclinical and epidemiological data being available. This emergent paradigm involves the clinical consideration (where appropriate) of prescriptive dietary modification/improvement, and/or the select judicious use of nutrient-based supplementation to prevent or manage psychiatric disorders. In the last several years, significant links have increasingly been established between dietary quality and mental health (although not all data are supportive). Maternal and early-life nutrition may also affect the mental health outcomes in offspring. In respect to nutraceutical research, like with many recent conventional drug studies, results are fairly mixed across the board, and in many cases there is not emphatic evidence to support the use of nutraceuticals in various psychiatric disorders. This may in part be due to a preponderance of recent studies within the field revealing marked placebo effects. Due to current indicators pointing towards mental disorders having an increasing burden of disease, bold and innovative approaches on a societal level are now required. In light of the widespread use of nutrient supplements by those with and without mental disorders, it is also critical that scientifically rigorous methodologies be brought to bear on the assessment of the efficacy of these supplements, and to determine if, or what dose of, a nutrient supplement is required, for whom, and when, and under what circumstances. More simple studies of additional isolated nutrients are not of great benefit to the field (unless studied in supra-dosage in an individualised, biomarker-guided manner), nor, based on recent data, is the research of 'shotgun' formulations of nutraceuticals. The next critical step for the field is to design psychiatric interventional studies for both dietary modification and nutraceuticals, based on more of a personalised medicine approach, using biomarkers (e.g. nutrient deficiencies, inflammatory cytokine levels, genomic assessment, microbiome analysis) and a person's dietary patterns and individual macro/micronutrient requirements.

Nutritional psychiatry: Towards improving mental health by what you eat

Does it matter what we eat for our mental health? Accumulating data suggests that this may indeed be the case and that diet and nutrition are not only critical for human physiology and body composition, but also have significant effects on mood and mental wellbeing. While the determining factors of mental health are complex, increasing evidence indicates a strong association between a poor diet and the exacerbation of mood disorders, including anxiety and depression, as well as other neuropsychiatric conditions. There are common beliefs about the health effects of certain foods that are not supported by solid evidence and the scientific evidence demonstrating the unequivocal link between nutrition and mental health is only beginning to emerge. Current epidemiological data on nutrition and mental health do not provide information about causality or underlying mechanisms. Future studies should focus on elucidating mechanism. Randomized controlled trials should be of high quality, adequately powered and geared towards the advancement of knowledge from population-based observations towards personalized nutrition. Here, we provide an overview of the emerging field of nutritional psychiatry, exploring the scientific evidence exemplifying the importance of a well-balanced diet for mental health. We conclude that an experimental medicine approach and a mechanistic understanding is required to provide solid evidence on which future policies on diet and nutrition for mental health can be based.

The efficacy and safety of nutrient supplements in the treatment of mental disorders: a meta-review of meta-analyses of randomized controlled trials

The role of nutrition in mental health is becoming increasingly acknowledged. Along with dietary intake, nutrition can also be obtained from "nutrient supplements", such as polyunsaturated fatty acids (PUFAs), vitamins, minerals, antioxidants, amino acids and pre/probiotic supplements. Recently, a large number of meta-analyses have emerged examining nutrient supplements in the treatment of mental disorders. To produce a meta-review of this top-tier evidence, we identified, synthesized and appraised all meta-analyses of randomized controlled trials (RCTs) reporting on the efficacy and safety of nutrient supplements in common and severe mental disorders. Our systematic search identified 33 meta-analyses of placebo-controlled RCTs, with primary analyses including outcome data from 10,951 individuals. The strongest evidence was found for PUFAs (particularly as eicosapentaenoic acid) as an adjunctive treatment for depression. More nascent evidence suggested that PUFAs may also be beneficial for attention-deficit/hyperactivity disorder, whereas there was no evidence for schizophrenia. Folate-based supplements were widely researched as adjunctive treatments for depression and schizophrenia, with positive effects from RCTs of high-dose methylfolate in major depressive disorder. There was emergent evidence for N-acetylcysteine as a useful adjunctive treatment in mood disorders and schizophrenia. All nutrient supplements had good safety profiles, with no evidence of serious adverse effects or contraindications with psychiatric medications. In conclusion, clinicians should be informed of the nutrient supplements with established efficacy for certain conditions (such as eicosapentaenoic acid in depression), but also made aware of those currently lacking evidentiary support. Future research should aim to determine which individuals may benefit most from evidence-based supplements, to further elucidate the underlying mechanisms.