The Role of the Gut Microbiota in Dietary Interventions for Depression and Anxiety

Abstract

There is emerging evidence that an unhealthy dietary pattern may increase the risk of developing depression or anxiety, whereas a healthy dietary pattern may decrease it. This nascent research suggests that dietary interventions could help prevent, or be an alternative or adjunct therapy for, depression and anxiety. The relation, however, is complex, affected by many confounding variables, and is also likely to be bidirectional, with dietary choices being affected by stress and depression. This complexity is reflected in the data, with sometimes conflicting results among studies. As the research evolves, all characteristics of the relation need to be considered to ensure that we obtain a full understanding, which can potentially be translated into clinical practice. A parallel and fast-growing body of research shows that the gut microbiota is linked with the brain in a bidirectional relation, commonly termed the microbiome–gut–brain axis. Preclinical evidence suggests that this axis plays a key role in the regulation of brain function and behavior. In this review we discuss possible reasons for the conflicting results in diet–mood research, and present examples of areas of the diet–mood relation in which the gut microbiota is likely to be involved, potentially explaining some of the conflicting results from diet and depression studies. We argue that because diet is one of the most significant factors that affects human gut microbiota structure and function, nutritional intervention studies need to consider the gut microbiota as an essential piece of the puzzle.

Differences in Gut Microbiome Composition between Senior Orienteering Athletes and Community-Dwelling Older Adults

“…In accordance with previous data, we show that depression and anxiety are significantly lower among senior orienteering athletes compared to community-dwelling older adults. Depression and anxiety are known to be associated with an altered gut microbiota composition that is most likely due to changes in the microbiota-gut-brain axis, the bidirectional relationship between the gut microbiota and brain [75]. One of the major factors influencing this pathway is diet and, among other factors, a change in eating habits due to increased psychological distress has been proposed to contribute to the alterations of the gut microbiota associated with depression and anxiety [76].…”

“…One of the major factors influencing this pathway is diet and, among other factors, a change in eating habits due to increased psychological distress has been proposed to contribute to the alterations of the gut microbiota associated with depression and anxiety [76]. However, the relationship between diet and depression and anxiety needs to be further investigated as the results from dietary intervention studies are contradictory and the directionality and mechanisms are currently unclear as reviewed by Bear et al [75]. In accordance with these observations, a recent systematic review of the field shows that so far there is no consensus within human studies regarding the question about which bacterial taxa would be most relevant to depression [77].…”

Gut Microbiome Associated with the Psychoneurological Symptom Cluster in Patients with Head and Neck Cancers

“…In contrast, supplementation of high fat diet with high fibers has shown to reverse the depleted levels of Bifidobacteria and butyrate-producing bacteria [ 53 ]. Thus, the gut microbiome has been proposed as one important component in nutritional intervention studies to improve mental health outcomes such as anxiety and depression [ 54 ]. Patients with cancer reported malnutrition and changes in diet composition [ 55 ], which may adjust the relationship between gut microbiome and PNS.…”

Environmental Enrichment as a Strategy to Confront Social Isolation Under the COVID-19 Pandemic

“…Bidirectional communication between the brain and the gut microbiome, known as the microbiota–gut–brain axis, is strongly supported by a vast and growing body of scientific evidence. Studies show that changes in these interactions and their associated behavioral changes imply the pathophysiology of not only classic brain–intestinal communication disorders, such as irritable bowel syndrome and functional gastrointestinal disorders, but also psychiatric and neurological conditions, including mood disorders and affection, anxiety, depression, autism spectrum disorders, neurodegenerative disorders, multiple sclerosis, and chronic pain (Cryan and Dinan, 2012 ; Fung et al, 2017 ; Roager and Licht, 2018 ; Madison and Kiecolt-Glaser, 2019 ; Osadchiy et al, 2019 ; Bear et al, 2020 ).…”

“…Such evidence shows the importance and relevance of environmental enrichment manifested in nutritional standards, such as diets rich in fresh foods, fibers, use of probiotics, prebiotics and psychobiotics, omega-3, food poor in processed foods, refined carbohydrates, fat, and chemical additives, in order to modulate and balance the microbial composition of the intestine and, consequently, promote the health of the individual (Wang et al, 2016 ; Bermúdez-Humarám, 2019 ; Liao et al, 2019 ; Bear et al, 2020 ).…”