The relationship between the gut microbiome and mental health is one of the most intriguing topics in microbiome research. Mounting evidence suggests that the gut microbiome can influence brain function via what’s known as the microbiome-gut-brain axis. The gut microbiome is the trillions of microorganisms in the gut that perform important functions in the immune system and metabolism by providing essential inflammatory mediators, nutrients, and vitamins.

The concept of the gut-brain axis relates to the vagus nerve, the body’s longest nerve, which runs from the brainstem to the lowest part of the intestines. This nerve serves as sort of a two-way highway, sending signals from the brain to the gut to regulate digestion and bringing signals from the gut to the brain. This provides a possible pathway for neurotransmitters – chemicals such as serotonin and dopamine – produced by the gut to receptors in the brain, where they may affect mood and behavior.

A new systematic review shows anxiety might be alleviated by regulating gut bacteria. These results suggest that if you experience anxiety symptoms, it might help to take steps to regulate the microorganisms in your gut using probiotic supplements or by changing your dietary habits.

Probiotics are living organisms found naturally in some foods that are also known as “friendly” because they fight against harmful bacteria and prevent them from settling in the gut.

A team of researchers from the Shanghai Mental Health Center at Shanghai Jiao Tong University School of Medicine in China set out to investigate if there was evidence to support the improvement of anxiety symptoms by regulating the gut microbiome. They reviewed 21 studies including more than 1,500 people; 14 studies used probiotics to regulate the microbiome and 7 studies used non-probiotic ways, such as adjusting daily diets.

Overall, more than half of the studies (11 of 21 studies) showed a positive effect on anxiety symptoms by regulating the gut microbiome. Six of the 7 studies (86%) without probiotics found dietary interventions were effective. The researchers stated that changing your diet could have more of an impact on gut bacteria than introducing specific types of bacteria via a probiotic supplement.

Most of the studies did not report serious side effects. Four studies reported mild side effects, such as dry mouth and diarrhea. More studies are needed to clarify these results but in addition to the use of psychiatric drugs for treatment, “we can also consider regulating intestinal flora to alleviate anxiety symptoms,” concluded the researchers.

Current research on the gut microbiome and mood disorders is still in its early stage. Stay tuned for more results from ongoing studies like this in the near future.

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