Nutritional Psychiatry

'An apple a day'?: Psychiatrists, psychologists and psychotherapists report poor literacy for nutritional medicine: international survey spanning 52 countries

According to Sarris (2019), the field of ‘nutritional psychiatry’ has been advancing rapidly over the last few years, with evidence of significant links between diet quality with mental health and the possible influence of maternal and early-life nutrition on the offspring’s psychological well-being leading to the clinical recommendation of modifying/improving diet and the use of nutrient-based (nutraceutical) supplementation to prevent or manage psychiatric disorders. As data on the use of nutraceuticals in psychiatric disorders is not completely convincing, possibly due partly to the emergence of studies showing marked placebo effects, novel, bold and innovative approaches on a societal level are warranted to tackle the increasing burden of mental disorders. The author expresses the desire to see the rigorous evaluation of the nutrient supplements being used currently by people with and without mental disorders, in order to inform others if the supplement is required, at what dose, for whom they are recommended, and when is the appropriate time to use these nutraceuticals. Psychiatric intervention studies for dietary alteration and nutraceuticals should be based on more of a personalised medicine approach, combining the information collected from markers such as nutrient deficiencies, inflammatory cytokine levels, genomic assessment and analysis of microbiome, as well as individual dietary patterns and micronutrient/macronutrient requirements.

This is a comment from Jacka et al. (2018) responding to the hypothesis by Molendijk et al. on the large effect size seen in the SMILES trial (the first intervention study to test dietary improvement as a treatment strategy for depression). While this present article accepts that there is the limitation of expectation bias in lifestyle observation trials, it can be argued that the substantial association between diet alteration with depression score changes is likely a causal effect and unlikely to be due to inadequate blinding. Jacka and her team (2018) have economically evaluated the SMILES trial and have had largely replicated results since its publication and emphasize the importance of the first trial in the field of nutritional psychiatry research.

Due to the high prevalence of mental/neurological disorders and the evolution of the modern diet (energy-dense, fiberless), dissecting the relationship between diet/nutrition and the prevention, development, and management of mental disorders is particularly important, according to this 2017 paper. While mental disorders have been projected to increase exponentially in the coming years, many studies have advocated the consumption of specific nutrients, given the proven influence of omega-3 fatty acids, Vitamin B, C, D and E, folic acid, iron, zinc, selenium, and magnesium, on various neuro-chemical modulatory reactions and thus mental health outcome. Annadurai et al. (2017) highlights the important role of nutrition as a predictor for both mental health and other noncommunicable diseases (NCD) such as diabetes for example. This means that by improving nutritional aspects, both mental health and NCD outcomes can be potentially enhanced. Evidence is currently available, demonstrating reductions in psychiatric symptoms by 50% following micronutrient therapy combined with standard treatment. Dietary interventions are considered to be a cost-effective public health strategy that may involve policy changes on food production and processing, and legislative measures e.g. imposing fat tax for junk foods. While professionals such as psychiatrists may be informed of the impact diet has on mental health but this paper emphasizes the need for strategic direction for comprehensive and multidisciplinary management, in order to tackle this ever growing burden of mental health disorders.

Jacka et al. (2017) executed this 12-week, single blind, randomised controlled trial to investigate the efficacy of a dietary improvement program for the treatment of major depressive episodes. The intervention consisted of seven individual nutritional consulting sessions delivered by a clinical dietician. The control condition was comprised of a social support protocol adhering to the same visit schedule and length. Of the 67 individuals who enrolled in this trial (33 = diet intervention, 34 = control), 55 participants were using some form of therapy: 21 using psychotherapy and pharmacotherapy combined; 9 were on psychotherapy alone; and 25 were exclusively using pharmacotherapy. With 31 participants in the diet support group and 25 in the social support group with complete datasets at 12 weeks, the dietary support group was found to have significantly improved MADRS (assesses depression symptomatology) between baseline and 12 weeks, compared to the social support group (p<0.001). Remission, defined as a MADRS score <10, was achieved for 32.3% (n = 10) and 8.0% (n = 2) of the intervention and control groups, respectively; the number needed to treat (NNT) based on remission scores was 4.1 (95% CI of NNT 2.3-27.8); and a sensitivity analysis discovered that the impact of the intervention was robust to violations of MAR assumptions. Jacka et al. (2017) believe that these results demonstrate that improvements made to diet may be an efficacious and accessible treatment option for major depression and also benefit common comorbidities.

Jacka (2017) provides her thoughts on the relatively new but promising field of research that is 'Nutritional Psychiatry'. Nutraceuticals have emerged as possible monotherapy and adjuvant treatments in mental disorders and diet modification interventions can potentially prevent and treat depression (since diet quality has been associated with risk of developing common mental disorders such as depression). It is also believed that nutritional interventions should target the immune system, oxidative biology, brain plasticity and the microbiome-gut-brain axis due to the advancing knowledge on the relationships between diet, nutrition and mental health. But there are limitations in this field including data deficit and several methodological problems (heterogeneity, residual confounding, measurement error, difficulty measuring and ensuring dietary adherence in intervention studies). This article points out the current challenges facing this area of research, such as replicating, refining and scaling up the diet strategies that have shown promise, confirming biological pathways and mediators of identified associations, and conducting scientifically robust nutraceutical and 'psychobiotic' interventions that also assess predictors of treatment response. Additionally, observational and experimental studies on psychosis looking at diet-related risk factors and treatments should be conducted, and researchers in this field are urged to continue advocating policy changes supporting the improvement of the food environment.

Guu et al. (2019) tell us about the literature review and a Dephi process conducted by the subcommittee of the International Society for Nutritional Psychiatry Research, aimed at developing a consensus-based practice guideline for clinical use of ω-3 polyunsaturated fatty acids (n-3 PUFAs) in major depressive disorder (MDD) that is focused on general concepts, acute treatment strategy, depression recurrence monitoring and prevention, use in special populations, and potential safety issues. The key guidelines advised clinicians and practitioners to validate clinical diagnoses, physical conditions, and measurement-based psychopathological assessments in the therapeutic settings when recommending n-3 PUFAs in the treatment of depression. The recommended dosage is 1-2 g of net eicosapentaenoic acid (EPA) daily, which can come in the form of pure EPA or an EPA/docosahexaenoic acid (DHA) combination with a ratio of EPA/DHA >2. The quality of n-3 PUFAs may influence therapeutic activity, and patients on n-3 PUFAs should be monitored on their gastrointestinal, metabolic and dermatological conditions. While the expert consensus panel agrees for n-3 PUFAs to be used appropriately in pregnant women, children and the elderly with MDD, and in high-risk populations for prevention, the next step in this area of research is applying the clinical knowledge of n-3 PUFAs with personalization in subgroups of MDD with low omega-3 index/many inflammatory markers.

Appropriately managing diet and nutrition could prevent and treat psychiatric disorders, which is why this paper aims to provide practical recommendations for the prevention and treatment of depression specifically, by borrowing Opie’s five key dietary recommendations and adding Matsuoka & Hamazaki’s (2016) own hypotheses. This paper promotes increased consumption of fruits, vegetables, legumes, whole-grain cereals, nuts, and seeds, while the intake of processed foods, fast foods, commercial baked goods, and sweets should be limited. The population can benefit from replacing unhealthy foods with wholesome nutritious foods, obtaining higher amounts of omega-3 fatty acids from foods, and being mindful of probiotic gut bacteria. Following particular dietary patterns such as the Mediterranean, Norwegian, or Japanese diet are recommended. Although the biological mechanisms by which diet influences people’s mental state has not been fully elucidated and full associations between nutrition and mental disorders have not been examined in randomized controlled trials, implementation of multiple healthy dietary practices appear to reduce the risk of developing depression, based on current evidence. Importantly, effective nutrition-related approaches are applicable for a wide population since an individual can alter their lifestyle or dietary practices at any time, which is what makes the discovery of high-quality studies in this area and the implementation of nutritional psychiatry within clinical practice extremely important.

This 2014 paper claims that consuming fermented foods is relevant in the association between traditional dietary practices with positive mental health, proclaiming that there are still unexplored connections between many aspects of physiology with the microbes living in and on human bodies. The researchers are expanding their knowledge on the ways in which fermentation alters dietary items pre-consumption, and in turn, their understanding of how the end- and by-products of these fermentation processes may act upon the intestinal microbiota community is also increasing. Selhub et al. (2014) believe that the microbiota may, to some degree, regulate the inflammatory and oxidative actions of traditional dietary components. It was also argued that well-controlled fermentation often amplifies specific nutrient and phytochemical contents of foods, which creates a strong argument for its association with mental health. Also, the microbes linked with fermented foods, such as the Lactobacillus and Bifidobacteria species, are believed to influence brain health.

This 2019 paper demonstrates the importance of a well-balanced diet for mental health by providing an overview of the emerging field of nutritional psychiatry. Although evidence confirming a strong association between poor diet with manifestations of mood disorders such as depression and anxiety is increasing, the link between nutrition and mental health is yet to be unequivocally proven. Common beliefs about the role of certain foods are not backed up by proper research and current epidemiological data on diet and mental health do not provide information about causality or underlying mechanisms. Randomized controlled trials should be of high quality, robust, and designed to accumulate knowledge from population-based observations required for implementing a personalized nutrition approach. The goal of future studies should be to elucidate these mechanisms and to find a suitable experimental medicine plan that would help set up successful policies on diet and nutrition on mental health in the future.

While additional strategies are encouraged to reduce the disease burden that mental illnesses pose, Marx et al. (2017) identifies diet quality as a risk factor for mental illness that can be modified. This review provides an overview of the field that is nutritional psychiatry, discussing possible neurobiological mechanisms by which mental state is modulated by diet, the use of dietary and nutraceutical interventions in mental disorders, and recommendations for further research. Potential biological pathways related to mental disorders include inflammation, oxidative stress, the gut microbiome, epigenetic modifications and neuroplasticity, while diet quality has been consistently associated in epidemiological studies with mental health and in particular with depression, across numerous age groups and populations. Moreover, Marx et al. (2017) observed significant clinical benefit from a dietary intervention in clinically diagnosed individuals participating in their recently published intervention trial. Future studies can investigate promising avenues in this field such as nutraceuticals (n-3 fatty acids, folate, S-adenosylmethionine, N-acetyl cysteine and probiotics) or continue vital research on the efficacy of interventions in large clinically relevant samples, especially focusing on patients with schizophrenia, bipolar and anxiety disorders.