Nutritional psychiatry

Adana et al (2019) predict that Europe in the coming decades will see a rise in the burden of psychiatric disorders, mood disorders and stress-induced cognitive vulnerabilities, and they highlight the importance of continuing research on the role of diet in mental health. This is because of mounting evidence that the relationship between diet and mood extends beyond heaving a contented sigh after a nice meal. For instance, DiNicolantonio et al (2017) report that ‘sugar meets many of the criteria for a substance of abuse and could be potentially addictive in humans’, while Marx et al (2017) state that ‘recent systematic reviews examining the association between diet and common mental disorders have shown healthy dietary patterns to be inversely associated with the probability of, or risk for, depression’.

Marx et al (2017) consider that the potential biological processes involved in the diet and mental health relationship primarily implicate inflammation, oxidative stress, and neuroplasticity, ‘with the gut microbiome as a key mediating pathway for each of these processes.’ This theme is expanded on by Mörkla et al (2020) who note the importance of the gut-brain axis, a bidirectional communication pathway between the intestine and brain, connecting the enteric nervous system to the central nervous system. For example, Mörkla et al (2020) cite evidence showing a reduction in the number of bacterial species in a range of mental disorders, as well as obesity, observing that intestinal bacteria intervene directly in our neurotransmitter metabolism, especially the serotonin metabolism, which is significant from a psychiatric perspective. And after a 12-week, randomised controlled trial of a modified Mediterranean diet model in the treatment of moderate to severe depression, Jacka et al (2017) concluded that ‘dietary improvement may provide an efficacious and accessible treatment strategy for the management of this highly prevalent mental disorder, the benefits of which could extend to the management of common co-morbidities.’