Nutritional Psychiatry: From Concept to the Clinic

Nutrition Education in Psychiatry Residency Programs: A Call to Action

The burden of disease attributable to mental health is expected to rise in the coming decades. Poor nutritional status is considered a modifiable risk factor for general mental health. In fact, nutrition interventions are now accepted as a core strategy in mental healthcare to combat physical health inequalities and life-expectancy gap in people with certain psychiatric disorders. However, most psychiatrists are not familiar with evidence for the potential therapeutic benefits of diet in psychiatric illness, and this may be related to sparse nutrition education for physicians. Thus, there is a need to integrate nutritional management in psychiatric practice, but there is a gap in medical education that would support this practice. Here, we discuss evidence for and challenges in 1) assessing diet quality in psychiatric illness, 2) recommending improvements in diet quality and specific dietary patterns in psychiatric illness, and 3) recommending dietary supplements in psychiatric illness. This discussion serves as a call to develop nutrition curricula within psychiatry residency programs.

An Overview of the Potential Role of Nutrition in Mental Disorders in the Light of Advances in Nutripsychiatry

PURPOSE OF REVIEW

As research on the potential impact of nutrition on mental disorders, a significant component of global disability continues to grow the concepts of "nutritional psychiatry, psycho-dietetics/nutripsychiatry" have taken their place in the literature. This review is a comprehensive examination of the literature on the the potential mechanisms between common mental disorders and nutrition and evaluates the effectiveness of dietary interventions.

RECENT FINDINGS

Inflammation, oxidative stress, intestinal microbiota, mitochondrial dysfunction, and neural plasticity are shown as potential mechanisms in the relationship between mental disorders and nutrition. As a matter of fact, neurotrophic factors, which make important contributions to repair mechanisms throughout life, and neuronal plasticity, which plays a role in mental disorders, are affected by nutritional factors. In metabolism, the antioxidant defense system works with nutritional cofactors and phytochemicals. A balanced, planned diet that provides these components is more likely to provide nutrients that increase resilience against the pathogenesis of mental disorders. Nutrition can be considered a risk factor for mental disorders. Therefore, developing public health strategies focused on improving diet may help reduce the global burden of mental disorders and other related diseases.

Adherence to unhealthy diets is associated with altered frontal gamma-aminobutyric acid and glutamate concentrations and grey matter volume: preliminary findings

OBJECTIVES

Common mental disorders (CMD) are associated with impaired frontal excitatory/inhibitory (E/I) balance and reduced grey matter volume (GMV). Larger GMV (in the areas that are implicated in CMD-pathology) and improved CMD-symptomatology have been observed in individuals who adhere to high quality diets. Moreover, preclinical studies have shown altered neurometabolites (primarily gamma-aminobutyric acid: GABA and glutamate: GLU) in relation to diet quality. However, neurochemical correlates of diet quality and how these neurobiological changes are associated with CMD and with its transdiagnostic factor, rumination, is unknown in humans. Therefore, in this study, we examined the associations between diet quality and frontal cortex neuro-chemistry and structure, as well as CMD and rumination in humans.

METHODS

Thirty adults were classified into high and low diet quality groups and underwent 1H-MRS to measure medial prefrontal cortex (mPFC) metabolite concentrations and volumetric imaging to measure GMV.

RESULTS

Low (vs High) diet quality group had reduced mPFC-GABA and elevated mPFC-GLU concentrations, as well as reduced right precentral gyrus (rPCG) GMV. However, CMD and rumination were not associated with diet quality. Notably, we observed a significant negative correlation between rumination and rPCG-GMV and a marginally significant association between rumination and mPFC-GLU concentrations. There was also a marginally significant association between mPFC-GLU concentrations and rPCG-GMV.

DISCUSSION

Adhering to unhealthy dietary patterns may be associated with compromised E/I balance, and this could affect GMV, and subsequently, rumination.

Dismantling the myth of "all foods fit" in eating disorder treatment

We call for a reevaluation of the long-standing dogmatic nutritional principle that "all foods fit" for all cases of eating disorders (EDs) and its corollary, "there are no bad foods" (for anyone ever) during ED treatment. Based on accumulated scientific research, we challenge these ideologies as outdated, confusing, and potentially harmful to many patients. We review the evidence that indicates the folly of these assumptions and show there are a variety of exceptions to these rules, including (1) food allergies, sensitivities, and intolerances, (2) religious and spiritual preferences or doctrines, and (3) the ubiquitous emergence and widespread availability of ultra-processed foods leading to the potential development of addiction-like eating and a higher prevalence of various medical and psychiatric comorbidities, as well as higher mortality. This evidence supports a nutritional psychiatry approach that should be integrated into (rather than dissociated from) ED treatment research and practice.

The Potential Role of the Ketogenic Diet in Serious Mental Illness: Current Evidence, Safety, and Practical Advice

The ketogenic diet (KD) is a high-fat, low-carbohydrate diet that mimics the physiological state of fasting. The potential therapeutic effects in many chronic conditions have led to the gaining popularity of the KD. The KD has been demonstrated to alleviate inflammation and oxidative stress, modulate the gut microbiota community, and improve metabolic health markers. The modification of these factors has been a potential therapeutic target in serious mental illness (SMI): bipolar disorder, major depressive disorder, and schizophrenia. The number of clinical trials assessing the effect of the KD on SMI is still limited. Preliminary research, predominantly case studies, suggests potential therapeutic effects, including weight gain reduction, improved carbohydrate and lipid metabolism, decrease in disease-related symptoms, increased energy and quality of life, and, in some cases, changes in pharmacotherapy (reduction in number or dosage of medication). However, these findings necessitate further investigation through larger-scale clinical trials. Initiation of the KD should occur in a hospital setting and with strict care of a physician and dietitian due to potential side effects of the diet and the possibility of exacerbating adverse effects of pharmacotherapy. An increasing number of ongoing studies examining the KD's effect on mental disorders highlights its potential role in the adjunctive treatment of SMI.

Modifiable lifestyle factors influencing psychiatric disorders mediated by plasma proteins: A systemic Mendelian randomization study

BACKGROUND

Psychiatric disorders are emerging as a serious public health hazard, influencing an increasing number of individuals worldwide. However, the effect of modifiable lifestyle factors on psychiatric disorders remains unclear.

METHODS

Genome-wide association studies (GWAS) summary statistics were obtained mainly from Psychiatric Genomics Consortium and UK Biobank, with sample sizes varying between 10,000 and 1,200,000. The two-sample Mendelian randomization (MR) method was applied to investigate the causal associations between 45 lifestyle factors and 13 psychiatric disorders, and screen potential mediator proteins from 2992 candidate plasma proteins. We implemented a four-step framework with step-by-step screening incorporating two-step, univariable, and multivariable MR.

RESULTS

We found causal effects of strenuous sports or other exercise on Tourette's syndrome (OR [95%CI]: 0.0047 [5.24E-04-0.042]); lifelong smoking index on attention-deficit hyperactivity disorder (10.53 [6.96-15.93]), anxiety disorders (3.44 [1.95-6.05]), bipolar disorder (BD) (2.25 [1.64-3.09]), BD II (2.89 [1.81-4.62]), and major depressive disorder (MDD) (2.47 [1.90-3.20]); and educational years on anorexia nervosa (AN) (1.47 [1.22-1.76]), and MDD (0.74 [0.66-0.83]). Five proteins were found to have causal associations with psychiatric disorders, namely ADH1B, GHDC, STOM, CD226, and TP63. STOM, a membrane protein deficient in the erythrocytes of hereditary stomatocytosis patients, may mediate the effect of educational attainment on AN.

LIMITATIONS

The mechanisms underlying the effects of lifestyle factors on psychiatric disorders require further investigation.

CONCLUSIONS

These findings could help assess the risk of psychiatric disorders based on lifestyle factors and also support lifestyle interventions as a prevention strategy for mental illness.

Perceptions of Mental Health Professionals on Nutritional Psychiatry as an Adjunct Treatment in Mainstream Psychiatric Settings in New South Wales, Australia

Background Nutritional psychiatry refers to the practice of using food, or nutrition, as alternative or complementary treatment for mental health disorders. It is a growing area of research that has shown links between the biological processes in the gut and how the food we consume can impact cognitive function, which then can impact our mood and behaviour. However, there is a lack of understanding on the knowledge and education of nutritional psychiatry in mental health clinicians, and further, how nutritional psychiatry, if at all, is practised in psychiatric clinical settings. Therefore, this study aims to investigate the perceptions, knowledge, and education of mental health professionals within the state of New South Wales, Australia regarding their clinical practice and knowledge of nutritional psychiatry.  Methods In this cross-sectional study, a self-administered structured questionnaire created by the authors was successfully completed by 40 mental health professionals (mental health nurses, occupational therapists, psychologists, medical officers, and other allied health workers) who were working in New South Wales, Australia. 49 questionnaires were attempted with nine excluded due to these being predominantly incomplete, including demographic data only or empty, ensuring integrity of the remaining data and analysis. The questionnaire aimed to uncover their perceptions, knowledge, and education in nutritional psychiatry and its role in mental health settings. The questionnaire included 16 questions that covered various themes such as the frequency and importance of discussing nutrition with patients, nutrition referrals for issues regarding nutrition, the value of including nutritional psychiatry in their clinical practice, and clinician training and willingness to train or gain further education in nutritional psychiatry. Data was analysed through a series of frequency tables to categorise patterns and identify patterns through the use of descriptive statistics in our analysis of the distribution of attitudes and practices among mental health professionals regarding nutritional psychiatry.  Results A total of 40 mental health clinicians successfully completed the survey and their results were analysed. The results suggest that most clinicians (85% to 93%) recognised the importance of nutrition in mental health, however, revealed various barriers which hindered their clinical practice such as a lack of time, knowledge, and access to nutritional services. Further, 54% of clinicians rated their knowledge of nutritional psychiatry as low, however, 92% revealed that they would attend nutritional psychiatry training if given the opportunity. Additionally, the clinicians reported varied levels of education in nutrition, with 43% reporting no education at all on nutrition in their preclinical studies.  Conclusions Clinicians recognise the importance of nutrition in mental health settings, but revealed lack of time, knowledge, and nutritional services as barriers in clinical practice. Further, clinicians reported a lack of pre-clinical education on nutrition together with an overwhelming interest in engaging with nutritional psychiatry education if it were made available. These conclusions provide important insights for higher education and health policy.

Women with Schizophrenia Have Difficulty Maintaining Healthy Diets for Themselves and Their Children: A Narrative Review

Severe psychiatric disorders such as schizophrenia are inevitably linked to unemployment, meagre per capita income, and residence in disadvantaged, poorly resourced neighbourhoods. This means difficult access to healthy food and is particularly problematic for pregnant women and mothers with children to feed. The necessity of taking antipsychotic drugs is an additional barrier to healthy eating because these drugs are associated with serious cognitive, psychological, behavioural, and metabolic sequelae. Being ill with psychosis makes it extremely difficult to maintain a healthy diet; nutritional deficiencies result, as do medical complications. The results of present literature review confirm the gravity of the problem and suggest a number of potentially useful clinical interventions.

[The Therapeutic Potential of Prebiotics and Probiotics in Child and Adolescent Psychiatric Disorders]

The Therapeutic Potential of Prebiotics and Probiotics in Child and Adolescent Psychiatric Disorders Abstract: This short review summarizes the literature available on therapeutic interventions with prebiotics and probiotics and their potential use in psychiatric disorders in childhood, adolescence, and adulthood. Most studies of children and adolescents are done on ADHD and autism spectrum disorders, whereas single reports exist largely on positive effects on cognitive symptoms and quality of life. Initial studies regarding anorexia nervosa point to a potential effect of weight gain and reduction of gastrointestinal symptoms. To date, the effects of prebiotics and probiotics in depression, bipolar disorder, anxiety disorders, and schizophrenia have been mainly investigated in adults. The best reported evidence exists for depression, whereas the effects on depressive symptomatology are small. Positive effects are seen on gastrointestinal symptoms in these disorders. Given these positive effects, the mixed literature reports may result from very heterogeneous study designs. Nevertheless, the high potential of prebiotics and probiotics may be seen for minors with mental health problems. Further studies that include child and adolescent psychiatric populations and reflect the complexity of the gut-brain axis are urgently needed.

Nutritional counseling needs of patients with mental disorders in psychiatric care: A cross-sectional survey

BACKGROUND

The exploration of diet and nutrition as they relate to mental health and psychiatric disorders is a developing field. Anxiety, depression, and pharmacological treatments used to treat these disorders are likely to have side effects that induce decreases in activity and irregular eating habits, resulting in persistent nutritional imbalance. Unhealthy dietary patterns are associated with an increased risk of developing physical and mental health conditions. Despite this, nutritional support to patients in psychiatric care is not adequate.

AIMS

This study aimed to determine the factors underlying the need for nutritional counseling among patients with a mental disorder in psychiatry. The factors explored are eating-related symptoms, eating behavior, interest in food, seeking nutritional counseling, and impact on quality of life (QOL).

METHODS

We utilized a cross-sectional study design. Eligible patients were asked to complete a questionnaire regarding physical measurements and nutritional counseling. In addition, patients' diagnoses and blood test data were referenced from their medical records. The analysis focused on two groups: those who desired to consult a nutritionist and those who did not.

RESULTS

Ninety-three patients completed the study. The nutritional status and need for nutritional counseling in psychiatry patients indicates that patients with dietary problems requested nutritional counseling (p < .001). Patients who were more likely to need nutritional counseling had lower QOL in daily life (p = .011), pain/discomfort (p = .024), and anxiety/depression (p = .010) on the EuroQol 5-Dimension 5-level (EQ-5D-5L).

CONCLUSIONS

Patients with mental disorders who need nutritional counseling tend to have food-related problems and low QOL. It is necessary to establish an interdisciplinary system for nutritional counseling.

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.

Effects of a high-prebiotic diet versus probiotic supplements versus synbiotics on adult mental health: The "Gut Feelings" randomised controlled trial

Background

Preliminary evidence supports the use of dietary interventions and gut microbiota-targeted interventions such as probiotic or prebiotic supplementation for improving mental health. We report on the first randomised controlled trial (RCT) to examine the effects of a high-prebiotic dietary intervention and probiotic supplements on mental health.

Methods

"Gut Feelings" was an 8-week, 2 × 2 factorial RCT of 119 adults with moderate psychological distress and low prebiotic food intake. Treatment arms: (1) probiotic supplement and diet-as-usual (probiotic group); (2) high-prebiotic diet and placebo supplement (prebiotic diet group); (3) probiotic supplement and high-prebiotic diet (synbiotic group); and (4) placebo supplement and diet-as-usual (placebo group). The primary outcome was assessment of total mood disturbance (TMD; Profile of Mood States Short Form) from baseline to 8 weeks. Secondary outcomes included anxiety, depression, stress, sleep, and wellbeing measures.

Results

A modified intention-to-treat analysis using linear mixed effects models revealed that the prebiotic diet reduced TMD relative to placebo at 8 weeks [Cohen's d = -0.60, 95% confidence interval (CI) = -1.18, -0.03; p = 0.039]. There was no evidence of symptom improvement from the probiotic (d = -0.19, 95% CI = -0.75, 0.38; p = 0.51) or synbiotic treatments (d = -0.03, 95% CI = -0.59, 0.53; p = 0.92). Improved anxiety, stress, and sleep were noted in response to the prebiotic diet while the probiotic tentatively improved wellbeing, relative to placebo. No benefit was found in response to the synbiotic intervention. All treatments were well tolerated with few adverse events.

Conclusion

A high-prebiotic dietary intervention may improve mood, anxiety, stress, and sleep in adults with moderate psychological distress and low prebiotic intake. A synbiotic combination of high-prebiotic diet and probiotic supplement does not appear to have a beneficial effect on mental health outcomes, though further evidence is required. Results are limited by the relatively small sample size.

Clinical trial registration

https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=372753, identifier ACTRN12617000795392.

Omega-3 Polyunsaturated Fatty Acids Supplementation Alleviate Anxiety Rather Than Depressive Symptoms Among First-Diagnosed, Drug-Naïve Major Depressive Disorder Patients: A Randomized Clinical Trial

Background

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) augmentation of antidepressants has shown great potential in the prevention and treatment of major depressive disorders (MDD).

Objective

To investigate the effect of n-3 PUFAs plus venlafaxine in patients with first-diagnosed, drug-naïve depression.

Method

A total of 72 outpatients with first-diagnosed depression were recruited. The daily dose of 2.4 g/day n-3 PUFAs or placebo plus venlafaxine was used for over 12 weeks. The outcomes were assessed by the Hamilton depression scale (HAMD), Hamilton anxiety scale (HAMA), Beck depression inventory (BDI), and Self-rating anxiety scale (SAS).

Results

Both groups exhibited improvement on clinical characteristics at week 4 and week 12 compared with baseline. The rate of responders for anxiety in n-3 PUFAs group (44.44%) was significantly higher than that in placebo group (21.21%) at week 4 (χ² = 4.182, p = 0.041), while week 12 did not show a difference (χ² = 0.900, p = 0.343). The rate of responders for depression at both week 4 (χ² = 0.261, p = 0.609) and week 12 (χ² = 1.443, p = 0.230) showed no significant difference between two groups. Further analysis found that Childhood Trauma Questionnaire (CTQ) had positive correlation with HAMA (r = 0.301, p = 0.012), SAS (r = 0.246, p = 0.015), HAMD (r = 0.252, p = 0.038) and BDI (r = 0.233, p = 0.022) with Pearson correlation analysis. Social Support Rating Scale (SSRS) had negative correlation with SAS (r = -0.244, p = 0.015) and BDI (r = -0.365, p = 0.000).

Conclusion

This trial found that n-3 PUFAs supplementation in favor of venlafaxine alleviated the anxiety symptoms rather than depressive symptoms at the early stage of treatment (4 weeks) for first-diagnosed, drug-naïve depressed patients. However, the advantage disappeared in long-term treatment. Furthermore, childhood abuse and social support are closely related to the clinical and biological characteristics of depression. Both childhood trauma and lack of social support might be predictors of poor prognosis in depression.

Clinical Trial Registration

[clinicaltrials.gov], identifier [NCT03295708].

The efficacy of nutritional supplements for the adjunctive treatment of schizophrenia in adults: A systematic review and network meta-analysis

Nutritional supplementations have been widely used as adjunctive treatments for schizophrenia. However, among these supplementations, of which the most beneficial is currently unknown. This study aimed to compare and rank the effectiveness of nutritional supplementations in the adjunctive treatments of schizophrenia. The four nutritional supplementations evaluated were: 1) folate acid or vitamin B12; 2) vitamin D; 3) N-acetyl cysteine (NAC); 4) Omega-3 polyunsaturated fatty acid, including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). 17 eligible RCTs with 1165 participants were included in this network meta-analysis based on study criteria. NAC supplementation was significantly more efficacious than folic acid or vitamin B12 [MD (95% CI): -6.6 (-10.8, -2.4)] and omega-3 polyunsaturated fatty acid [MD (95% CI): -5.1(-9.9, -0.8)] supplementation in the term of PANSS score changes. There were no significant differences in the PANSS score changes between NAC and vitamin D [MD (95% CI): -5.2 (-10.9, 0.5)] supplementations. The estimated ranking probabilities of treatments showed that NAC might be the most effective adjunctive intervention over all nutritional supplementations. These results indicate that NAC could improve PANSS score and it may be among the most effective nutritional supplementations in schizophrenia patients.

A Scoping Literature Review of the Relation between Nutrition and ASD Symptoms in Children

Autism spectrum disorder (ASD) is characterized by impairments in social interaction, communication skills, and repetitive and restrictive behaviors and interests. Even though there is a biological basis for an effect of specific nutrition factors on ASD symptoms and there is scientific literature available on this relationship, whether nutrition factors could play a role in ASD treatment is unclear. The goal of the current literature review was to summarize the available scientific literature on the relation between nutrition and autism spectrum disorder (ASD) symptoms in childhood, and to formulate practical dietary guidelines. A comprehensive search strategy including terms for ASD, nutrition factors (therapeutic diets, dietary patterns, specific food products, fatty acids and micronutrients) and childhood was developed and executed in six literature databases (Cinahl, Cochrane, Ovid Embase, PsycInfo, PubMed and Web of Science). Data from meta-analyses, systematic reviews and original studies were qualitatively summarized. A total of 5 meta-analyses, 29 systematic reviews and 27 original studies were retrieved that focused on therapeutic diets, specific food products, fatty acids and micronutrients and ASD symptoms during childhood. Results of the available studies were sparse and inconclusive, and hence, no firm conclusions could be drawn. There is currently insufficient evidence for a relation between nutrition and ASD symptoms in childhood, making it impossible to provide practical nutrition guidelines; more methodological sound research is needed.

Design and pilot evaluation of an evidence-based worksheet and clinician guide to facilitate nutrition counselling for patients with severe mental illness

BACKGROUND

Schizophrenia spectrum disorders (SSD) are severe, persistent mental illnesses resulting in considerable disability and premature mortality. Emerging evidence suggests that diet may be a modifiable risk factor in mental illness; however, use of nutritional counselling as a component of psychiatric clinical practice is limited. The objective of this project is the design and evaluate a worksheet and clinician guide for use in facilitating nutritional counseling in the context of existing mental health care.

METHODS

The worksheet and clinician guide were developed based on the results of a recent scoping review on the relationship between diet and mental health symptoms among individuals with SSD. A feedback process involved a focus group with psychiatrists and interviews with individuals with lived experience with psychosis. Participants were asked a series of structured and open-ended questions. Interviews were transcribed and data units were allocated to categories from an existing framework. The comments were used to guide modifications to the worksheet and clinician guide. A brief interview with all participants was completed to gather feedback on the final version.

RESULTS

Five psychiatrist participants and six participants with lived experience completed interviews. Participants provided positive comments related to the worksheet design, complexity and inclusion of interactive components. A novel theme emerged relating to the lack of nutritional counselling in psychiatric training and clinical practice. Many constructive comments were provided which resulted in meaningful revisions and improvements to the worksheet and clinician guide design and content. All participants were satisfied with the final versions.

CONCLUSIONS

A worksheet and clinician guide designed to facilitate nutritional counselling with individuals with SSD was found to be acceptable to all participants following a process of feedback and revision. Further research and dissemination efforts aimed at increasing the use of nutritional counselling in psychiatric practice are warranted.

Nutrition, nutritional deficiencies, and schizophrenia: An association worthy of constant reassessment

Schizophrenia is a mental health disorder that occurs worldwide, cutting across cultures, socioeconomic groups, and geographical barriers. Understanding the details of the neurochemical basis of schizophrenia, factors that contribute to it and possible measures for intervention are areas of ongoing research. However, what has become more evident is the fact that in targeting the neurochemical imbalances that may underlie schizophrenia, the type of response seen with currently available phamacotherapeutic agents does not provide all the answers that are needed. Therefore, the possible contribution of non-pharmacological approaches to schizophrenia management is worthy of consideration. In recent times, research is beginning to show nutrition may play a possibly significant role in schizophrenia, affecting its development, progression and management; however, while attempts had been made to examine this possible relationship from different angles, articles addressing it from a holistic point of view are not common. In this review, we examine existing scientific literature dealing with the possible relationship between nutrition and schizophrenia, with a view to elucidating the impact of diet, nutritional deficiencies and excesses on the aetiology, progression, management and outcome of schizophrenia. Secondly, the effect of nutritional supplements in prevention, as sole therapy, or adjuncts in schizophrenia management are examined.

Reframing anorexia nervosa as a metabo-psychiatric disorder

Anorexia nervosa (AN) is a serious and often fatal illness. Despite decades of research, investigators have failed to adequately advance our understanding of the biological aspects of AN that could inform the development of effective interventions. Genome-wide association studies are revealing the important role of metabolic factors in AN, and studies of the gastrointestinal tract are shedding light on disruptions in enteric microbial communities and anomalies in gut morphology. In this opinion piece, we review the state of the science through the lens of the clinical presentation of illness. We project how the integration of rigorous science in genomics and microbiology, in collaboration with experienced clinicians, has the potential to markedly enhance treatment outcome via precision interventions.

Nutrition, Exercise, and Stress Management for Treatment and Prevention of Psychiatric Disorders. A Narrative Review Psychoneuroendocrineimmunology-Based

Psychoneuroendocrineimmunology (PNEI) brings together knowledge acquired since the 1930s from endocrinology, immunology, neuroscience, and psychology. With PNEI, a model of research and interpretation of health and disease is emerging, which sees the human body as a structured and interconnected unit, where the psychological and biological systems are mutually coordinated. In the PNEI view, many factors could influence mental health, with the endocrine system involved in mediating the effects of environmental stress on mental health and inflammation in the onset and course of psychiatric disorders as a result of individual and collective conditions and behaviors. Among these, nutrition is one way by which the environment impacts physiology: indeed, many pieces of research showed that several elements (e.g., probiotics, fish oil, zinc) have a positive effect on mental disorders thus being potentially augmentation agents in treatment. Still, physical activity can moderate depressive symptoms, while prolonged stress increases the risk of psychopathology. Taken together, the PNEI-based approach may inform prevention and treatment strategies, also in the field of mental health care.

Therapeutic Opportunities for Food Supplements in Neurodegenerative Disease and Depression

Emerging evidence is showing nutrition as a crucial factor in the high prevalence and incidence of neurodegenerative mental disorders. Preventive interventions on neuroinflammation seem to be able to interfere with neurodegeneration. Supplementation of essential nutrients, such as long-chain-polyunsaturated fatty acids, vitamin E and mineral elements, may minimize inflammation, enhancing antioxidative defense, and lowering the risk and incidence of age-related diseases, such as cardiovascular diseases and neurodegenerative diseases. This manuscript reviews the current evidence on the role of neuroinflammation in the pathophysiology of neurodegenerative and mental disorders, and preventive strategies for food supplementation in these neuropsychiatric diseases. Dietary supplementation-based strategies have been demonstrated to be effective in subjects with mild cognitive impairment, while weaker results have been obtained in patients with advance neurodegenerative disease. Adjunctive supplementation has also been demonstrated to improve depression, this being of marked benefit considering the comorbidity between cognitive impairment/dementia and depression. Further research is needed to improve the prescriptive precision of supplementation in patients, and to better understand potential interactions with clinical and pharmacokinetic factors.

The Impact of Nutrients on Mental Health and Well-Being: Insights From the Literature

A good nutritional status is important for maintaining normal body function and preventing or mitigating the dysfunction induced by internal or external factors. Nutritional deficiencies often result in impaired function, and, conversely, intakes at recommended levels can resume or further enhance body functions. An increasing number of studies are revealing that diet and nutrition are critical not only for physiology and body composition, but also have significant effects on mood and mental well-being. In particular, Western dietary habits have been the object of several research studies focusing on the relationship between nutrition and mental health. This review aims to summarize the current knowledge about the relationship between the intake of specific micro- and macronutrients, including eicosapentaenoic acid, docosahexaenoic acid, alpha-tocopherol, magnesium and folic acid, and mental health, with particular reference to their beneficial effect on stress, sleep disorders, anxiety, mild cognitive impairment, as well as on neuropsychiatric disorders, all significantly affecting the quality of life of an increasing number of people. Overall data support a positive role for the nutrients mentioned above in the preservation of normal brain function and mental well-being, also through the control of neuroinflammation, and encourage their integration in a well-balanced and varied diet, accompanied by a healthy lifestyle. This strategy is of particular importance when considering the global human aging and that the brain suffers significantly from the life-long impact of stress factors.

Self-Reported Diet Quality Differentiates Nutrient Intake, Blood Nutrient Status, Mood, and Cognition: Implications for Identifying Nutritional Neurocognitive Risk Factors in Middle Age

Evidence for diet quality representing a modifiable risk factor for age-related cognitive decline and mood disturbances has typically come from retrospective, cross-sectional analyses. Here a diet screening tool (DST) was used to categorize healthy middle-aged volunteers (n = 141, 40–65 years) into “optimal” or “sub-optimal” diet groups to investigate cross-sectional associations between diet quality, cognitive function, and mood. The DST distinguished levels of nutrient intake as assessed by Automated Self-Administered 24-h dietary recall and nutrient status, as assessed by blood biomarker measures. Compared with the “sub-optimal” group, the “optimal” diet group showed significantly higher intake of vitamin E (p = 0.007), magnesium (p = 0.001), zinc (p = 0.043) and fiber (p = 0.015), higher circulating levels of vitamin B6 (p = 0.030) and red blood cell folate (p = 0.026) and lower saturated fatty acids (p = 0.012). Regarding psychological outcomes, the “optimal” diet group had significantly better Stroop processing than those with a “sub-optimal” diet (p = 0.013). Regression analysis revealed that higher DST scores were associated with fewer mood disturbances (p = 0.002) and lower perceived stress (p = 0.031), although these differences were not significant when comparing “optimal” versus “sub-optimal” as discrete groups. This study demonstrates the potential of a 20-item diet screen to identify both nutritional and psychological status in an Australian setting.

Impact of review method on the conclusions of clinical reviews: A systematic review on dietary interventions in depression as a case in point

Background

The recommendations of experts who write review articles are a critical determinant of the adaptation of new treatments by clinicians. Several types of reviews exist (narrative, systematic, meta-analytic), and some of these are more vulnerable to researcher bias than others. Recently, the interest in nutritional interventions in psychiatry has increased and many experts, who are often active researchers on this topic, have come to strong conclusions about the benefits of a healthy diet on depression. In a young and active field of study, we aimed to investigate whether the strength of an author’s conclusion is associated with the type of review article they wrote.

Methods

Systematic searches were performed in PubMed, Web of Science, Cochrane Database of Systematic Reviews, and Google Scholar for narrative reviews and systematic reviews with and without meta-analyses on the effects of diet on depression (final search date: May 30^th, 2020). Conclusions were extracted from the abstract and discussion section and rated as strong, moderate, or weak by independent raters who were blind to study type. A benchmark on legitimate conclusion strength was based on a GRADE assessment of the highest level of evidence. This systematic review was registered with PROSPERO, number CRD42020141372.

Findings

24 narrative reviews, 12 systematic reviews, and 14 meta-analyses were included. In the abstract, 33% of narrative reviews and 8% of systematic reviews came to strong conclusions, whereas no meta-analysis did. Narrative reviews were 8.94 (95% CI: 2.17, 36.84) times more likely to report stronger conclusions in the abstract than systematic reviews with and without meta-analyses. These findings were similar for conclusions in the discussion section. Narrative reviews used 45.6% fewer input studies and were more likely to be written by authors with potential conflicts of interest. A study limitation is the subjective nature of the conclusion classification system despite high inter-rater agreements and its confirmation outside of the review team.

Conclusions

We have shown that narrative reviews come to stronger conclusions about the benefits of a healthy diet on depression despite inconclusive evidence. This finding empirically underscores the importance of a systematic method for summarizing the evidence of a field of study. Journal editors may want to reconsider publishing narrative reviews before meta-analytic reviews are available.

The Role and the Effect of Magnesium in Mental Disorders: A Systematic Review

Introduction: Magnesium is an essential cation involved in many functions within the central nervous system, including transmission and intracellular signal transduction. Several studies have shown its usefulness in neurological and psychiatric diseases. Furthermore, it seems that magnesium levels are lowered in the course of several mental disorders, especially depression. Objectives: In this study, we wish to evaluate the presence of a relationship between the levels of magnesium and the presence of psychiatric pathology as well as the effectiveness of magnesium as a therapeutic supplementation. Methods: A systematic search of scientific records concerning magnesium in psychiatric disorders published from 2010 up to March 2020 was performed. We collected a total of 32 articles: 18 on Depressive Disorders (DD), four on Anxiety Disorders (AD), four on Attention Deficit Hyperactivity Disorder (ADHD), three on Autism Spectrum Disorder (ASD), one on Obsessive–Compulsive Disorder (OCD), one on Schizophrenia (SCZ) and one on Eating Disorders (ED). Results: Twelve studies highlighted mainly positive results in depressive symptoms. Seven showed a significant correlation between reduced plasma magnesium values and depression measured with psychometric scales. Two papers reported improved depressive symptoms after magnesium intake, two in association with antidepressants, compared to controls. No significant association between magnesium serum levels and panic or Generalized Anxiety Disorder (GAD) patients, in two distinct papers, was found. In two other papers, a reduced Hamilton Anxiety Rating Scale (HAM-A) score in depressed patients correlated with higher levels of magnesium and beneficial levels of magnesium in stressed patients was found. Two papers reported low levels of magnesium in association with ADHD. Only one of three papers showed lower levels of magnesium in ASD. ED and SCZ reported a variation in magnesium levels in some aspects of the disease. Conclusion: The results are not univocal, both in terms of the plasma levels and of therapeutic effects. However, from the available evidence, it emerged that supplementation with magnesium could be beneficial. Therefore, it is necessary to design ad hoc clinical trials to evaluate the efficacy of magnesium alone or together with other drugs (antidepressants) in order to establish the correct use of this cation with potential therapeutic effects.

Mendelian randomisation for nutritional psychiatry

Nutritional psychiatry is a growing area of research, with several nutritional factors implicated in the cause of psychiatric ill-health. However, nutritional research is highly complex, with multiple potential factors involved, highly confounded exposures and small effect sizes for individual nutrients. This Personal View considers whether Mendelian randomisation provides a solution to these difficulties, by investigating causality in a low-risk and low-cost way. We reviewed studies using Mendelian randomisation in nutritional psychiatry, along with the potential opportunities and challenges of using this approach for investigating the causal effects of nutritional exposures. Several studies have identified nutritional exposures that are potentially causal by using Mendelian randomisation in psychiatry, offering opportunities for further mechanistic research, intervention development, and replication. The use of Mendelian randomisation as a foundation for intervention development facilitates the best use of resources in an emerging discipline in which opportunities are rich, but resources are often poor.

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.