Certain bacteria can affect your brain function, according to new research published in the journal Gastroenterology.
In a new study done at UCLA, researchers discovered that brain function among healthy women changed when they consumed foods high in probiotics.
These changes were present while at rest and during an emotion-recognition task.
And what they found was that the bacterial environment in the gut can change brain activity dramatically.
According to researchers, these findings are particularly important because they can have major implications for future dietary and drug interventions to improve brain function.
Dr. Kirsten Tillisch, an associate professor of medicine at UCLA's David Geffen School of Medicine and lead author of the study, said:
"Many of us have a container of yogurt in our refrigerator that we may eat for enjoyment, for calcium or because we think it might help our health in other ways. Our findings indicate that some of the contents of yogurt may actually change the way our brain responds to the environment. When we consider the implications of this work, the old sayings 'you are what you eat' and 'gut feelings' take on new meaning."
Prior research has confirmed that the brain can send signals to the gut, which explains why stress can often be the cause of digestive problems.
The authors say their study proves what many have suspected for a long time.
Tillisch added that "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."
The study involved 36 women between the ages of 18 and 55 split into two groups.
- Group one ate a yogurt containing a mix of several probiotics twice a day for four weeks
- Group two consumed a diary product that contained no probiotics
- Group three ate no product at all
Researchers used functional magnetic resonance imaging (fMRI) scans before and after the four-week study period to measure brain activity.
The emotion-recognition task involved making the women look at pictures of angry or frightened faces and matching them to other faces with the same expressions. This was done in order to measure the affective and cognitive brain regions' response to visual stimulus.
What they found was that during the emotional reactivity task, the women who consumed the yogurt containing probiotics experienced less activity in areas of the brain that process internal body sensations – the insula and the somatosensory cortex.
Women who consumed the probiotic yogurt also had decreased activity in emotion-, cognition- and sensory-related areas of the brain compared to those who didn’t.
And at rest, women consuming probiotics showed more connectivity between an important brainstem region called the periaqueductal grey and areas of the prefrontal cortex responsible for cognition.
Tillisch said he was surprised to see that brain effects occurred in various different regions, including those that have nothing to do with emotion, such as sensory processing.
Dr. Emeran Mayer, a professor of medicine, physiology and psychiatry at the David Geffen School of Medicine at UCLA and the study's senior author, said that the fact that signals sent from the intestine to the brain can be influenced by dietary change, will hopefully drive further research on digestive and mental disorders.
"There are studies showing that what we eat can alter the composition and products of the gut flora, in particular, that people with high-vegetable, fiber-based diets have a different composition of their microbiota, or gut environment, then people who eat the more typical. A western diet that is high in fat and carbohydrates. Now we know that this has an effect not only on the metabolism but also affects brain function."
Researchers have now turned their attention to finding the chemicals that the gut produces which send signals to the brain.
In addition, they want to find out whether symptoms of poor digestion including bloating, abdominal pain and altered bowel movements correlate to variations in brain response.
Future research will also look into whether probiotics have any effect on mood symptoms and anxiety.
The researchers are also excited to see how changing the intestinal content could potentially help treat Alzheimer's disease.
Benefits of Probiotics
According to a recent study published in the British Journal of Sports Medicine, professional long-distance runners who took a probiotic had shorter and less severe episodes of respiratory illness than those who ingested a placebo.
Scientists at Michigan State University reported in the Journal of Cellular Physiology, that mice given a natural probiotic supplement produce healthier bones.
And according to the prestigious international journal Proceedings of the National Academy of Sciences (PNAS). Probiotics have the potential to alter brain neurochemistry and treat anxiety and depression-related disorders.