We investigated whether a Mediterranean-style diet (MedDiet) supplemented with fish oil can improve mental health in adults suffering depression. Adults with self-reported depression were randomized to receive fortnightly food hampers and MedDiet cooking workshops for 3 months and fish oil supplements for 6 months, or attend social groups fortnightly for 3 months. Assessments at baseline, 3 and 6 months included mental health, quality of life (QoL) and dietary questionnaires, and blood samples for erythrocyte fatty acid analysis. n = 152 eligible adults aged 18-65 were recruited (n = 95 completed 3-month and n = 85 completed 6-month assessments). At 3 months, the MedDiet group had a higher MedDiet score (t = 3.95, P < 0.01), consumed more vegetables (t = 3.95, P < 0.01), fruit (t = 2.10, P = 0.04), nuts (t = 2.29, P = 0.02), legumes (t = 2.41, P = 0.02) wholegrains (t = 2.63, P = 0.01), and vegetable diversity (t = 3.27, P < 0.01); less unhealthy snacks (t = -2.10, P = 0.04) and red meat/chicken (t = -2.13, P = 0.04). The MedDiet group had greater reduction in depression (t = -2.24, P = 0.03) and improved mental health QoL scores (t = 2.10, P = 0.04) at 3 months. Improved diet and mental health were sustained at 6 months. Reduced depression was correlated with an increased MedDiet score (r = -0.298, P = 0.01), nuts (r = -0.264, P = 0.01), and vegetable diversity (r = -0.303, P = 0.01). Other mental health improvements had similar correlations, most notably for increased vegetable diversity and legumes. There were some correlations between increased omega-3, decreased omega-6 and improved mental health. This is one of the first randomized controlled trials to show that healthy dietary changes are achievable and, supplemented with fish oil, can improve mental health in people with depression.

Major depressive disorder is a common, chronic condition that imposes a substantial burden of disability globally. As current treatments are estimated to address only one-third of the disease burden of depressive disorders, there is a need for new approaches to prevent depression or to delay its progression. While in its early stages, converging evidence from laboratory, population research, and clinical trials now suggests that dietary patterns and specific dietary factors may influence the risk for depression. However, largely as a result of the recency of the nutritional psychiatry field, there are currently no dietary recommendations for depression. The aim of this paper is to provide a set of practical dietary recommendations for the prevention of depression, based on the best available current evidence, in order to inform public health and clinical recommendations. Five key dietary recommendations for the prevention of depression emerged from current published evidence. These comprise: (1) follow ‘traditional’ dietary patterns, such as the Mediterranean, Norwegian, or Japanese diet; (2) increase consumption of fruits, vegetables, legumes, wholegrain cereals, nuts, and seeds; (3) include a high consumption of foods rich in omega-3 polyunsaturated fatty acids; (4) replace unhealthy foods with wholesome nutritious foods; (5) limit your intake of processed-foods, ‘fast’ foods, commercial bakery goods, and sweets. Although there are a number of gaps in the scientific literature to date, existing evidence suggests that a combination of healthful dietary practices may reduce the risk of developing depression. It is imperative to remain mindful of any protective effects that are likely to come from the cumulative and synergic effect of nutrients that comprise the whole-diet, rather than from the effects of individual nutrients or single foods. As the body of evidence grows from controlled intervention studies on dietary patterns and depression, these recommendations should be modified accordingly.

Objective: Non-pharmacological approaches to the treatment of depression and anxiety are of increasing importance, with emerging evidence supporting a role for lifestyle factors in the development of these disorders. Observational evidence supports a relationship between habitual diet quality and depression. Less is known about the causative effects of diet on mental health outcomes. Therefore a systematic review was undertaken of randomised controlled trials of dietary interventions that used depression and/or anxiety outcomes and sought to identify characteristics of programme success.Design: A systematic search of the Cochrane, MEDLINE, EMBASE, CINAHL, PubMed and PyscInfo databases was conducted for articles published between April 1971 and May 2014.Results: Of the 1274 articles identified, seventeen met eligibility criteria and were included. All reported depression outcomes and ten reported anxiety or total mood disturbance. Compared with a control condition, almost half (47 %) of the studies observed significant effects on depression scores in favour of the treatment group. The remaining studies reported a null effect. Effective dietary interventions were based on a single delivery mode, employed a dietitian and were less likely to recommend reducing red meat intake, select leaner meat products or follow a low-cholesterol diet.Conclusions: Although there was a high level of heterogeneity, we found some evidence for dietary interventions improving depression outcomes. However, as only one trial specifically investigated the impact of a dietary intervention in individuals with clinical depression, appropriately powered trials that examine the effects of dietary improvement on mental health outcomes in those with clinical disorders are required.

Alzheimer’s disease (AD) is the leading cause of dementia and the most common neurodegenerative disease in the elderly. Furthermore, AD has provided the most positive indication to support the fact that inflammation contributes to neurodegenerative disease. The exact etiology of AD is unknown, but environmental and genetic factors are thought to contribute, such as advancing age, family history, presence of chronic diseases such as cardiovascular disease (CVD) and diabetes, and poor diet and lifestyle. It is hypothesised that early prevention or management of inflammation could delay the onset or reduce the symptoms of AD. Normal physiological changes to the brain with ageing include depletion of long chain omega-3 fatty acids and brains of AD patients have lower docosahexaenoic acid (DHA) levels. DHA supplementation can reduce markers of inflammation. This review specifically focusses on the evidence in humans from epidemiological, dietary intervention, and supplementation studies, which supports the role of long chain omega-3 fatty acids in the prevention or delay of cognitive decline in AD in its early stages. Longer term trials with long chain omega-3 supplementation in early stage AD are warranted. We also highlight the importance of overall quality and composition of the diet to protect against AD and dementia.