Probiotics for mental health

A group of men who took probiotic capsules daily for a month felt less stressed and performed better on memory tests, according to a study presented to the Society for Neuroscience meeting in Chicago over the weekend.

Study participants were given a capsule containing more than a billion Bifidobacterium longum 1714 bacteria for a month, before switching to a placebo for the second month.

The researchers from University College Cork found after the first month that not only did the participants report less stress than both before the trial and during the second month, but they also had lower levels of the stress hormone cortisol in their blood stream.

Author Ted Dinan suggests that it's possible the B. longum bacteria are releasing substances that activate the vagus nerve, which connects the brain and the gut, but further research is needed to show what's really going on.

Earlier this year researchers found that students who ate foods rich in probiotics, such as yoghurt, pickles, and sauerkraut, reported feeling less social anxiety and neuroticism.

"By their very nature, probiotics are safe bacteria, and if we can delineate those that have benefits for mental health, that would be a major advance for neuroscience and psychiatry," said Dinan. "My hope is that within the next five years we’ll have a probiotic or two on the market that will be effective for treating mild forms of anxiety and depression."