PROBIOTICS found in natural yogurt could help to boost a person’s mood as they affect brain function, according to new research.
The study found that those who ate probiotic yoghurt twice daily for a month showed altered brain function, both in resting brain activity and in response to an ’emotional attention task’, which was designed to monitor how the brain responded to certain emotions.
Dr Kirsten Tillisch, of UCLA’s School of medicine, who led the study, said that the results illustrated the close link between the gut and emotions.
She said: “When we consider the implications of this work, the old sayings ‘you are what you eat’ and ‘gut feelings’ take on new meaning.
“Time and time again we hear from patients that they never felt depressed or anxious until they started experiencing problems with their gut.
“Our study shows that the gut-brain connection is a two-way street.”
Tillisch’s team recruited 36 women of a healthy weight aged between 18 and 53. They were assigned to one of three groups. One group ate a yogurt with live bacterial cultures containing probiotic strains, another ate a dairy product which contained no living bacteria, and another was given no dairy products at all.
Before and after the one-month study period, the researchers conducted functional magnetic resonance imaging (fMRI) brain scans on the women. In each session, they started with a five-minute scan of the brain at rest, while the women lay still with their eyes closed. Afterwards, the participants were asked to perform an ‘emotional faces attention task’, in which their brains were scanned while they matched a series of angry or fearful faces on a computer screen to other faces that appeared.
The results showed that during the emotional task, women who ate the probiotic yogurt had reduced activity in a brain network that included the somatosensory cortex – which receives sensory information – and the insula, a brain region that integrates sensory feedback from internal parts of the body including the gut.
Women who ate non-probiotic yogurt or no dairy showed either no change, or an increase of activity in this network over time. In the resting state, the brain scans of the women who ate probiotic yogurt showed stronger connectivity in a neural network which connects the area of the brain which responds to pain and emotional stimuli to the decision-making areas of the brain.
Meanwhile the women who ate no dairy, however, had stronger connectivity to sensory and emotion-related parts of the brain.
While the mechanisms behind these changes are unclear, it is clear that gut bacteria send molecular signals to the brain that can change over time.
The research team hopes to identify which signals from the gut bacteria lead to a shift in brain activity. People with digestive conditions linked to an imbalance in gut bacteria, such as irritable bowel syndrome, might show such shifts in brain response if they are treated with probiotics and specific probiotic strains in yogurt could also have health benefits such as relieving anxiety, stress, and other mood symptoms over time.