Uncovering the links between diet, gut health and immunity

A preclinical study from the University of Sydney found that a high-protein diet can change the gut microbiota and trigger an immune response. The researchers say the study brings us a step closer to understanding how diet affects gut health and immunity.

“The focus of our work is how the gut microbiota, the trillions of bacteria that inhabit the gut, affect the immune system,” said Associate Professor Laurence Macia of the Charles Perkins Center and University School of Medicine and Health.

“Our ultimate goal is to understand how we can manipulate bacteria to optimize health, and we know that one of the easiest ways to change the microbiota is to change diet.”

Traditionally, however, scientists have focused on the role of dietary fiber in maintaining a healthy gut.

In this first study of its kind, published in nature communicationsThe Charles Perkins Center team used sophisticated modeling to explore the impact of 10 diets with a different composition of macronutrients: protein, fat, and carbohydrates on mice.

They found that a high protein diet changed the composition and activity of the gut microbiota.

Mice fed a high protein diet increased their production of bacterial extracellular vesicles, complex cargo that contains bacterial information such as DNA and proteins. The body subsequently saw this activity as a threat and triggered a sequence of events in which immune cells traveled to the intestinal wall.

“Here we found that the protein had a big impact on the gut microbiota and it wasn’t so much the type of bacteria that was there, but the type of activity. In essence, we discovered a new form of protein-mediated communication between gut bacteria and the host,” said Associate Professor Macia.

While it’s too early to say whether this research could translate to humans, the researchers say the activation of the immune system can be either good or bad news.

“By increasing antibodies in the gut, you might see strong protection against potential pathogens, for example, salmonella, but on the downside, an activator immune system could mean you have a higher risk of colitis, a inflammatory bowel diseaseor autoimmune diseases such as Crohn’s disease,” said lead author and postdoctoral researcher Jian Tan.

The results appear consistent with the population impacts of modern diets, with the Western world seeing lower rates of gastrointestinal infection but higher rates of chronic disease.

This advancement in knowledge was made possible by the fusion of academic disciplines for which the Charles Perkins Center has become well known.

The study used the geometric framework for nutrition developed by Professor Stephen Simpson and Professor David Raubenheimer, which stems from the study of ecology.

“The ‘nutritional geometry’ framework allows us to graph foods, meals, diets and dietary patterns together based on their nutrient composition, and this helps researchers see otherwise overlooked patterns in the links between certain diets, health and disease,” said Professor Simpson. , Academic Director of the Charles Perkins Center.

“This is the first time this model has been applied in immunology and it could only have happened here at the Charles Perkins Center. We are excited about what might come next,” said Associate Professor Macia.