Improving gut bacteria could help curb anxiety, according to a review of medical studies.
Probiotics and sticking to a balanced diet have both been found to have a positive effect on symptoms.
Eating more fruit and vegetables appears to be the most beneficial intervention for boosting 'good bacteria', scientists said.
The Chinese research is the latest in a long line of studies to link mental health to microorganisms found in the gut.
Improving gut bacteria, especially with a varied diet, could help curb anxiety, according to a review of medical studies by researchers in Shanghai
Researchers from the Shanghai Jiao Tong University School of Medicine reviewed 21 studies that looked at 1,503 people all together.
Around two thirds of them, 14, had chosen probiotics as interventions and seven chose non-probiotic ways, such as adjusting daily diets.
Probiotics are found in foods, such as kefir, yoghurt, sauerkraut, miso and pickles, and are also made into supplements with various strains.
Overall, more than half (52 per cent) of the studies, 11, showed regulating intestinal microbiota had a positive effect on anxiety symptoms.
Of the 14 studies that had used probiotics as the intervention, more than a third (36 per cent) found them to be effective in reducing anxiety symptoms.
Six of the seven studies that had used non-probiotics as interventions found those to be effective - an 86 per cent rate of effectiveness.
Some of the 21 studies had tried to improve gut bacteria while also allowing treatment as usual, such as anti-anxiety medication. But there were only reductions in anxiety symptoms with non-probiotic studies, compared with probiotic ones.