Gut bacteria might play role in reducing anxiety: Study

Anxiety levels in people are on a constant rise, but regulating it might be as easy as eating. A new study has found that controlling the microorganisms in the gut using probiotic and non-probiotic foods can aid in relieving anxiety.

The study, published in the journal General Psychiatry, highlighted anxiety symptoms that are common in people with mental problems and a variety of physical disorders, especially those related to stress.

Research has earlier indicated that gut microbiota - the trillions of microorganisms in the gut - perform important functions in the immune system and metabolism by providing essential inflammatory mediators, nutrients and vitamins - can help regulate brain function through something called the "gut-brain axis".

For the study, researchers reviewed 21 studies that had looked at 1,503 people. 14 studies had chosen probiotics as interventions to regulate intestinal microbiota (IRIFs), and seven chose non-probiotic ways, such as adjusting daily diets.

The researchers found that probiotic supplements in seven studies within their analysis contained only one kind of probiotic, two studies used a product that contained two kinds of probiotics, and the supplements used in the other five studies included at least three kinds.

11 of the 21 studies showed a positive effect on anxiety symptoms by regulating intestinal microbiota, meaning that more than half (52%) of the studies showed this approach to be effective.

Of the 14 studies that had used probiotics as the intervention, more than a third (36%) found them to be effective in reducing anxiety symptoms, while six of the remaining seven studies that had used non-probiotics as interventions found those to be effective - a 86% rate of effectiveness.

Some studies had used both the IRIF (interventions to regulate intestinal microbiota) approach and treatment as usual.

In the five studies that used treatment as usual and IRIF as interventions, only studies that had conducted non-probiotic ways got positive results, that showed a reduction in anxiety symptoms.

Studies only using IRIF, 80% were effective when using non-probiotic interventions, while only 45% were found to be effective when using probiotic ways.

The authors state one reason that non-probiotic interventions more effective than probiotic interventions were possible due to the fact that changing diet (a diverse energy source) could have more of an impact on gut bacteria growth.

However, the studies did not report any adverse effects, only four studies reported mild effects like dry mouth and diarrhoea.

Researchers at the Shanghai Jiao Tong University said, "We find that more than half of the studies included showed it was positive to treat anxiety symptoms by regulation of intestinal microbiota."

"It should be highlighted that the non-probiotic interventions were more effective than the probiotic interventions."

They also suggest that, in addition to the use of psychiatric drugs for treatment, "we can also consider regulating intestinal flora to alleviate anxiety symptoms.