Written by Erin Sanzone
“I have a bad gut feeling about this” may have more meaning than one has believed before. Dr. Margaret Morris works with gut bacteria at the University of South Wales in Sydney, Australia. Her research discusses how the foods we consume change the types of bacteria in our gut and how these gut bacteria and brain communicate. Dr. Morris works with rodents to determine the effect of consuming unhealthy, fast food on the memory and behavior of the mice.
Her previous research has highlighted the association between the brain and gut, called the gut-brain axis. Our brain and gut are in constant communication with each other, and their communication often has a great impact on our mood and thought processes. The vagus nerve sends signals from the brain to the digestive system, controlling hormones that regulate hunger and the speed of digestion. As the gut breaks down the food consumed, it releases chemical messengers. The chemical messengers are dispersed throughout the body. Some of the chemicals respond to the brain via the vagus nerve, in which hormones are released and affect mood, behaviors, and memory. Furthermore, the chemical messengers also control the immune system, where they help to protect the body from disease or infection. The process of the gut bacteria communicating with the brain is referred to as neurotransmission.
The bacteria in our gut are heavily dependent on the food consumed and therefore change the communication with our brain. To test this idea, Dr. Morris fed the rats of the experimental group junk food (mainly consisting of cake and French fries) for two weeks and the control group “healthy” foods, consisting of mainly vegetables. In order to test the rat’s memory, Dr. Morris and her lab placed the rat in a space with different pieces of furniture. The rat was then removed, and Dr. Morris moved the pieces of furniture in the space. If the rat had a good memory of the original position, it would sense the change and sniff the area where the objects once were. Dr. Morris discovered that after a two-week diet of fried and overall unhealthy foods, the memories of the rats in the experimental group were deteriorated as opposed to the rats that were fed healthy food.
Dr. Morris explained this based on gut bacteria diversity. The rats that consumed junk food had a significantly less diverse set of gut bacteria, which in turn limited their memory. However, after feeding the rats a probiotic, their memory improved. Science News described the probiotic as “a mix of beneficial gut bacteria.”
While Dr. Morris’s findings were based on rodents, and researchers cannot yet extrapolate their meaning to humans, Dr. John Cyran from the University College Cork has found through a series of human studies that altering the food consumed will alter human’s microbiome.. He set up an study design in which a group of health men drank a set of microbiomes for four weeks. After a month, the 22 men that he tested performed better in stress tests and memory tests, comparing to the baseline week 0.
While there still needs to be more research on the benefits of probiotics, Dr. Morris claims that for now, humans can focus on eating a healthy diet to promote diversity in the microbiome, boost “conversation” with the brain, and positively alter mood and behavior.
Brookshire, Bethany. “Belly Bacteria Can Shape Mood and Behavior.” Science News for Students, 14 June 2018, www.sciencenewsforstudents.org/article/belly-bacteria-can-shape-mood-and-behavior.