Dr. Justin Sonnenburg is an associate professor of microbiology and immunology at Stanford and Dr. Erica Sonnenburg is a senior research scientist in the Sonnenburg lab where they research many aspects the interaction between diet with the 100 trillion or so bacteria in the gut (specifically the colon) and how this impacts the health of the host (which in this case is a laboratory research mouse). In this episode we discuss the pivotal role fiber plays in fueling good bacteria in the gut to produce compounds that regulate the immune system including increasing the number of T regulatory cells, which are specialized types of immune cells that keep the immune system in check and prevent autoimmune responses, and how these compounds also increase other types of blood cells in the body in a process known as hematopoiesis. We also talk about how the lack of fiber in the typical American diet actually starves these good bacteria of their food. This has an effect not only on the immune system and autoimmune diseases but also results in the breakdown of the gut barrier, which leads to widespread inflammation and inflammatory diseases. Lastly, in this podcast, Dr. Erica Sonnenburg talks about how C-sections, have a negative effect on the infant’s gut due to the lack of exposure to bacteria present in the mother’s vaginal canal, and how the use of formula deprives the infant not only from the good bacteria present in Mom’s gut but also from special carbohydrates in breast milk that are good for the infant gut flora known as HMOs or human milk oligosaccharides.