Eating the Right Food to Boost Gut Bacteria Could Ease Symptoms of Anxiety

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Eating the right food could help to ease the symptoms of anxiety, scientists believe.

A study published in the journal General Psychiatry is the latest to suggest the makeup of our gut bacteria could affect our mental health because of what is known as the gut-brain axis. A balanced gut flora is believed to help keep our immune and nervous systems working, as well as the metabolism.

Anxiety disorders—the umbrella term for conditions such as Generalized Anxiety Disorder (GAD) and Social Anxiety Disorder—affect millions of people. Some 6.8 million people in the U.S. alone have GAD, according to the Anxiety and Depression Association of America. The symptoms vary from condition to condition, but can include feeling nervous or on edge; experiencing an impending sense of doom; and physical manifestations like struggling to sleep, sweating, and an increased heart rate. Currently, treatments include therapy, such as cognitive behavioral therapy, and medication like antidepressants.

To investigate whether anxiety can partly be treated by regulating the trillions of organisms—including bacteria—which live in our intestines, they looked at 21 existing studies involving 1,503 people. In 14 studies, scientists looked at the effects of probiotics on anxiety, while the remaining seven looked at approaches such as changing a person's diet, which didn't involve probiotics, including the low FODMAP diet. This is where a person cuts out foods which are not absorbed in the small intestine and leave behind a residue which ferments in the colon, potentially causing digestive problems.

Of the studies where participants took probiotics, 36 percent showed improvements in their anxiety symptoms. And of the studies not involving probiotics, 86 percent were effective.

"So we can easily find that although we can regulate the intestinal flora in two ways, the non-probiotic intervention is significantly better than the probiotic intervention," the authors wrote.

The authors highlighted that as their study was a meta-analysis of existing research, their conclusion was limited because the papers had different designs and assessments for anxiety. But they remained optimistic that their work could help to see the diet be used alongside other treatments for anxiety.

"In the clinical treatment of anxiety symptoms, in addition to the use of psychiatric drugs for treatment, we can also consider regulating intestinal flora to alleviate anxiety symptoms," the authors wrote. More work needs to be done to detail exactly how anxiety patients should be treated, they said.

Study co-author Jinghong Chen, professor of psychotic disorders at Shanghai Jiao Tong University School of Medicine and the executive editor-in-chief of General Psychiatry told Newsweek: "The proteins produced by the human microbiome can interfere with normal body processes, for example by interacting with or mimicking other proteins in the body.

"Most of these proteins have not been explored in detail. However, there appears to be a link between the populations of microorganisms in the human gut and diseases like Type 1 diabetes, Crohn's disease, and ulcerative colitis. Understanding more about the human microbiome should uncover the link to these and anxiety diseases. Once scientists discover which proteins play key roles in these diseases, they can then turn to working on controlling them to develop new treatments."

Ted Dinan, clinical advisor of Anxiety UK and principal investigator of a study into the microbiome at the University College Cork, who did not work on this study, told Newsweek: "There are over 1 kg of bacteria in the adult gut. They produce a variety of molecules that the brain requires. In depressed patients we have shown that the microbiota is far less diverse than in healthy subjects.

"So far there are no good studies looking at the gut microbes in anxiety."

"The literature is largely filled with rodent studies and the number of human interventions studies is very limited. Furthermore, most of the studies, in the analysis provided in this paper, are with relatively small numbers and less than optimal design. We need big well funded properly designed studies to make definite conclusions."

Anxiety isn't the only condition which scientists believe can be affected by diet. A study published last year suggested the Mediterranean diet could prevent depression. The diet is packed with plant-based foods including vegetables, fruits, legumes, olive oil and nuts, as well as fish.

This article has been updated to include comment from Ted Dinan and Jinghong Chen.