The Gut Microbiome and Diet in Psychiatry: Focus on Depression

Sarah Dash; Gerard Clarke; Michael Berk; Felice N. Jacka


Curr Opin Psychiatry. 2015;28(1):1-6. 

In This Article

Conclusion, Discussion, Future Direction

With depression currently one of the leading causes of global disease burden,[89] the imperative to develop effective prevention and treatment strategies is clear. The gut microbiome has been implicated as an important health determinant relevant to both physical and mental health. The emerging literature from this nascent field suggests that the recently established association between diet quality and depressive disorders[90] is likely to be, at least partly, mediated by the gut microbiota. Depressive symptoms prompt the increased consumption of high-fat, sugary foods,[91] although the long-term impact of these dietary habits is noxious.[92] Microbial changes perpetuated by poor diet may drive and exacerbate depressive symptoms. On the contrary, dietary improvement has been shown to prevent depression.[29,93] As a readily accessible and effective tool for modifying microbial composition, diet may provide a more acceptable alternative to drug therapy with unpleasant side effects, particularly in patients with milder symptoms of depression. This provides an important target for the prevention and treatment of common mental disorders.[24]

It is important to bear in mind that the field is in its early stages and has not yet been able to comprehensively identify and describe the composition of a 'healthy' gut, nor the full functional capacity of most bacterial phyla. Importantly, microbial composition seems to be individualized; overall, microbiome function can vary greatly between persons, yet different microbiome compositions between individuals can also have the same range of functions. Advances in analytical technology will continue to shed light on this rapidly developing field of investigation. Although early probiotic and dietary research provides support for diet as a possible target for microbial modification and in turn, the alleviation of mental health symptoms, there is a clear need for more high quality research, including randomized controlled trials, to investigate the effectiveness and feasibility of mental health improvement as a function of microbial modulation. Although pre and probiotics (whose presence is transient and dependant on continued consumption) offer tantalising promise for efficacy in psychiatry, holistic dietary changes may be necessary to promote long-term improvements in health.