Researchers from the University of College Cork (UCC) found that taking a dose of probiotic bacteria everyday may aid individuals to improve mental health and combat stress.
Previous studies from UCC revealed that administering probiotic bacteria in mice helped improve the subjects' memories and exude antidepressant effects.
In the new research, experts instructed 22 healthy men to take in one capsule containing billions of probiotic bacteria daily for a month then changed to a placebo capsule on the second month or vice-versa. Before and after the experiment, the memory and stress levels of the participants were examined. An electroencephalography (EEG) test to analyze brain activity was also performed. None of the study subjects knew the details of the capsules they were asked to take.
The findings of the study showed that those who took the probiotic capsule exhibited less anxiety and stress. In the morning, they also had lower amounts of cortisol, the stress hormone, compared to those who took the placebo.
As for their memory, those in the probiotics group scored higher on memory tests composed of object pairing activities.
"When they were given these bacteria they were less anxious and their capacity to memorize material seemed to be enhanced," said Ted Dinan, study lead author and head of Psychiatry at the UCC.
The results of the research are preliminary and have to be tested and confirmed on a large group of people. Nonetheless, this suggests that brain function may benefit from a safe strain of live bacteria known as Bifidobacterium longum (B longum).
Dinan said that although the effects of the probiotic were minimal, they were sufficient to help some individuals. "The effect was large enough for them to perceive less stress," he explained
B longum is just one of the hundreds of bacteria living inside the human gut. Majority of these gut bacteria absorb energy from substances absorbed in the intestine; however, it perform helpful tasks like digestion, prevention of bad bacteria and boosting of immune system.
The role of B longum on the brain should be investigated further. At present, Dinan thinks it might be possible that the bacteria secrete substances that stimulate the vagus nerve, which links the gut and brain. Another possibility is that the substances may reach the bloodstream and go to the brain.
In the next five years, Dinan hopes to have a probiotic available for consumers in need of treatment for depression and anxiety.
The findings of the study were presented at the Society for Neuroscience meeting in Chicago on Sunday, Oct. 18.
