Gut bacteria may also affect the immune system, which could in turn, influence the brain, Philip Burnet, researcher at the University of Oxford was quoted as saying. For the study, researchers recruited 45 healthy people aged 18 to 45 years to take either a probiotic supplement to 'good' bacteria or a placebo, every day for a period of three weeks.
They completed several computer tests to assess how they processed emotional information such as negative and positive words. During one test, people who took the supplement paid less attention to negative information and more attention to positive information, compared with people who took a placebo, the findings showed.
A similar effect was seen in people who took drugs for depression or anxiety and the findings suggested that the people in the supplement group had 'less anxiety about negative or threatening stimuli,' Burnet added.
Researchers are not sure of how changes in gut bacteria might affect the brain. Some researchers suspect that the vagus nerve - which conveys sensory information from the gut to the brain - plays a role, a news agency reported. The study appeared in the journal Psychopharmacology.