Kathy Magnusson, DVM, PhD

Professor, Department of Biomedical Sciences
College of Veterinary Medicine
Principal Investigator, Linus Pauling Institute
Oregon State University, Corvallis, OR

image of Dr. Kathy Magnusson
Abstract: The body is covered by bacteria, including the lining of the digestive tract. The number of bacteria in the gut outnumbers the body’s own cells. It has been known for a long time that the bacteria play a role in digestion, but a new field of study focused on the gut microbiota is finding that these bacteria can influence many organ systems in the body, including diseases of the digestive tract, the immune system and even the brain. There is increasing evidence for two-way communication between the gut bacteria and the nervous system. The microbiota signal the brain in multiple ways, including via cytokines released by inflammation, release of neurotransmitters or precursors by bacteria or enteroendocrine cells, or via sensory neurons in the vagus nerve. The nervous system can influence bacteria via norepinephrine. Diet can have major impacts on the microbiota and behavior. High energy diets produce alterations in the microbiota that are associated with deficits in long-term memory and cognitive flexibility. Prebiotics, foods that can promote the abundance of certain types of bacteria, have effects on decreasing anxiety and depression. Microbial metabolites, such as propionate and 4-ethylphenylsulfate, are associated with autism spectrum disorders. These studies suggest that the interrelationship between diet and the gut microbiota can have important impacts on brain health.