It seems an unlikely way to ease anxiety, but new research suggests that regulating the bacteria in your gut might help.
How? By eating the right foods and using supplements when appropriate, the researchers said.
Regulating the gut microbiota
As many as one-third of people suffer anxiety symptoms during their lives, including irrational fears, agitation, fatigue or panic attacks. Anxiety is common in people with mental health issues, especially stress-related disorders.
Studies suggest that microorganisms in the intestine (gut microbiota) may help regulate brain function through something called the gut-brain axis, and that mental disorders could be treated by regulating the gut microbiota. But there has been no proof of this, the researchers noted.
Hoping to learn more, the Chinese team reviewed 21 studies involving more than 1 500 people. Those studies examined whether the use of probiotics (foods and supplements containing good bacteria) or non-probiotic methods, such as adjusting daily diet, eased anxiety.
Eleven (52%) studies found that regulating gut microbiota had a positive effect. That included 36% of studies on the use of probiotics and 86% of those that looked at non-probiotics.
Non-probiotics more successful
Five studies used usual treatment along with either probiotics or non-probiotics. Of those studies, only those that used non-probiotics reduced anxiety symptoms.
Of the studies that aimed to regulate gut bacteria without other treatment, 80% of those with non-probiotics were effective, compared with 45% of those that used probiotics, according to the study published in the journal General Psychiatry.
The non-probiotics may have been more successful because changing diet could have a bigger impact on gut bacteria than introducing specific types of bacteria in a probiotic supplement, according to the researchers at Shanghai Jiao Tong University School of Medicine in China.
They also noted that some of the studies used different types of probiotics, which could have conflicted with each other. Many of those studies may also have been too short to significantly increase beneficial bacteria populations in the gut, they added.
Researchers noted that these were observational findings and do not prove cause and effect. But they said the results suggest that, along with medications, "we can also consider regulating intestinal flora to alleviate anxiety symptoms".
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