Probiotics are Beneficial to the Brain, New Study Suggests

Lisa Franchi June 03, 2013

For the first time, scientists have found evidence that bacteria ingested in food can affect the brain. The study, which was conducted by the UCLA team, revealed that women who consumed good bacteria through yoghurt showed altered brain function during the resting state and in response to an emotion recognition task.

The study also confirms what scientists knew all along – the brain sends signals to the brain. This time however, the researchers found that signals travel the opposite way as well.

The Gut-Brain Connection

The study involved 36 women between the ages of 18 and 55. The participants were grouped into three. One group ate yoghurt which contains a mix of several probiotics twice a day for four weeks. The other group consumed a dairy product that looked and tasted like yoghurt but contained no beneficial bacteria. The third group, which served as a control, ate no product at all.

Before and after the experiment, the participants went through MRI scans. Researchers looked at the women’s brain activities both while at rest and in response to an emotion-recognition task in which they viewed several pictures of angry or frightened faces and matched them to other faces showing the same emotion. The task was specifically chosen because previous research has shown that changes in gut flora are linked to changes in affective behaviours.

The researchers found that the women who consumed yoghurt showed a decrease in the activity of both the insula and the somatosensory cortex. The latter is the part of the brain that is involved during the emotional reactivity task while the former is the part that processes and integrates internal body sensations, including those from the gut.

Probiotics Alter the Brain

During the resting state, those who consumed probiotics showed improved connectivity between a major brainstem region known as the periaqueductal grey and the cognition-assisted areas of the prefrontal cortex. In response to the task, the probiotic group demonstrated the engagement of a widespread network in the brain that includes emotion-, cognition- and sensory-related areas. According to Dr Kirsten Tillisch, the lead author of the study and an associate professor of medicine at the David Geffen School of Medicine, University of California, Los Angeles (UCLA), they were surprised to find that the effects could be seen in many areas of the brain, including those that are involved in emotions and sensory processing.

This discovery provides significant implication for future research that could lead to the development of new dietary or drug interventions to improve brain function. The researchers are seeking to determine the specific chemicals produced by gut bacteria that may be triggering the transmission of signals to the brain. They also plan to study whether gastrointestinal problems such as bloating, altered bowel movements, and abdominal pain are linked to changes in the brain response. The study was published in the peer-reviewed journal Gastroenterology.

Source of this article:

Changing gut bacteria through diet affects brain function, UCLA study shows