Researchers examining gut microbiota influence on mental health found people with anxiety experience decreased microbial diversity and fewer short-chain fatty acid-producing bacteria – suggesting probiotics could improve anxiety symptoms.
A review published in Nutrients noted a study at China’s Zhejiang University found participants with anxiety disorder had lower diversity of microorganisms, less richness of microorganisms, higher levels of certain bacteria and lower levels of bacteria that produce short-chain fatty acids ‘linked to many different aspects of health’; even after participants experienced anxiety remission, the gut changes remained, ‘indicating the changes may affect generalised anxiety development’.
Another Chinese study at Xi’an Fourth Military Medical University found decreases in certain bacteria and increases in others among those with generalised anxiety disorder; the increases related to how severe the anxiety was, while others were associated with anxiety reduction.
Other Chinese research at Guangdong General Hospital found five bacterial traits might increase risk for anxiety disorders, and four may decrease risk. And a study at Shandong University noted a ‘complex relationship between gut microbiota, inflammatory and genetic factors, and development of anxiety disorders’.
A Sichuan University study found differences in microbiota between those with depression and those with generalised anxiety disorder – further suggesting ‘looking at gut microbiota could determine if someone has a depressive or anxiety disorder’. And a study at Nanjing’s Southeast University identified specific microbes and a metabolite that ‘could help determine severity of depressive symptoms’.
The review also cited research at China’s Guizhou Medical University which found similar gut microbiota compositions for healthy controls, and a Peruvian study where participants with functional gastroenteropathy (a complication of diabetes) also had participants with similar microbiota compositions.
The review authors commented: ‘Several biological mechanisms underpin the connection between bacterial presence/absence in the gut and anxiety symptoms.’
They noted the gut-brain axis connects the gut microbiota and central nervous system. Helpful bacteria like Lactobacillus help produce the neurotransmitter gamma-aminobutyric acid (GABA) which helps control stress response and anxiety; a decrease in the bacteria that produce GABA may be related to worse anxiety symptoms. Imbalances in gut microbiota can also contribute to systemic inflammation; and chronic inflammation may contribute to brain function changes and increased anxiety.
US psychotherapist Noah Kass told medicalnewstoday.com the review ‘reinforces the connection between gut flora and psychological distress’ and ‘suggests certain probiotic treatments, especially Lactobacillus strains, may help individuals with anxiety-related disorders.’
The review authors noted taking supplements like probiotics, using certain spices and eating fruits and vegetables ‘encourages growth of helpful gut microbiota while stopping the growth of damaging microorganisms’.
