The link between nutrition and mental health

Although a 1930s study of Scottish schoolchildren had observed that ‘poor nutrition has undoubtedly an effect on mental capacity …’ (Riddell, 1932), Grajek et al (2022) report that ‘the relationship between nutrition and patients’ mental status has been underappreciated, as evidenced by the lack of research conducted before the 21st century …’ with Adana et al (2019) predicting that Europe in coming decades will see an increased burden of psychiatric disorders, mood disorders and stress-induced cognitive vulnerabilities, and they advocate continued research on the role of diet in mental health.

The body's microbiome comprises some 200 trillion (2 x 1014) organisms and Hoffmann (2023) explains that it is adversely affected by the consumption of ultra-processed foods (UPFs) which lower the population of beneficial versus harmful gut bacteria that can promote ‘increased intestinal mucosal permeability, which in turn triggers an augmented immune response, cytokine production, and chronic neuroinflammation, a significant cause of mental illness.’ Expanding on this, Mörkla et al (2020) highlight 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, evidence cited by Mörkla et al (2020) shows a reduction in the number of bacterial species in a range of mental disorders and demonstrates how intestinal bacteria intervene directly in our neurotransmitter metabolism, especially serotonin metabolism, which is significant from a psychiatric perspective.