Study finds immunity linked to gut health and diet

Researchers from the University of Sydney said the results of a preclinical study conducted by the university have improved understanding of the effect of diet on immunity and gut health.

The University of Sydney study found that high-protein diets can trigger an immune response by altering the composition and activity of the gut microbiota, a collection of microorganisms that live in the gut.

Associate Professor Laurence Macia of the Charles Perkins Center and the University of Sydney’s School of Medicine and Health said in a press release that the team focused on the relationship between gut microbiota and immunity. .

“Our work focuses on how the gut microbiota — the trillions of bacteria that inhabit the gut — affects the immune system,” Macia said.

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

Traditionally, scientists have focused on the role of dietary fiber when studying the maintenance of a healthy gut.

In an email to The Epoch Times, Macia said it was because dietary fiber is not digestible by humans and therefore, although intact, reaches the colon, which contains the greatest amount. of bacteria.

“Dietary fiber is therefore the main source of energy for bacteria, while other components of the diet are used by the host,” Macia said.

Macia said changing the amount of dietary fiber in a person’s diet has a huge impact on gut health; it is easier to investigate.

Does a carnivorous diet encourage immune responses

This study explored the effect of 10 different diets, each with a different composition of macronutrients – proteins, fats and carbohydrates – on mice using sophisticated modelling.

The researchers found that when the mice were fed a high-protein diet, their production of bacterial extracellular vesicles, which carry complex cargoes containing bacterial information such as DNA and proteins, increased.

“We identified that high protein content increased the production of certain metabolites, which may be due to the direct utilization of protein by bacteria,” Macia said.

The increase in bacterial extracellular vesicles was interpreted as an attack on the organism, which triggered a sequence of events where immune cells traveled to the intestinal wall.

“Here, we found that protein had a huge impact on the gut microbiota, and it wasn’t so much what kind of bacteria was there, but what kind of activity was there,” Macia said.

“Essentially, we discovered a new communication pathway between gut bacteria and the host that was protein-mediated.”

Macia noted that as the results have not yet been validated in humans, researchers still need to know whether the immune response seen in the trial is good or bad for humans.

Lead author and postdoctoral researcher Jian Tan said researchers are aware that an increase in gut antibodies – proteins that neutralize foreign germs in the body – generates a higher level of protection against pathogens, such as salmonella. However, there is also evidence showing that an activated immune system may increase the risk of developing inflammatory bowel disease – a set of conditions in which part or all of the digestive tract is chronically inflamed.

One point the researchers noted is currently observable in modern diets since in the Western world, rates of gastrointestinal infections have declined, while rates of chronic disease have increased.

Unique modeling system that made the discovery possible

The study used a geometric framework devised by the Charles Perkins Center Academic Director, Professor Stephen Simpson and Professor David Raubenheimer in 2016, which is useful in the face of modern diets where there is an overabundance of food and overconsumption. of food. containing specific mixtures of nutrients.

Other frameworks look at the effect that individual components of a diet have on the body rather than looking at the effect that different diets, involving multiple components with different nutrient mixes, have on a person.

“Our framework throws down the gauntlet to the entire field of human nutrition,” Simpson said in a press release from the University of Sydney.

“This shows that a focus on single nutrients is unable to help us understand complex chronic diseases and that a nutrient balance approach can help solve the problem.”

Simpson said using the “nutritional geometry” framework allows researchers to observe patterns that would otherwise have been missed. The framework makes it possible to plot foods, diets, meals and eating habits together according to nutrient intake, helping researchers detect patterns in the links between diets, health and disease.

“Nutritional geometry” considers how mixtures of nutrients and other food components influence health and disease, rather than focusing on a single nutrient in isolation.

“Conventional thinking that demonizes fats, carbs or sugar in isolation as the causes of the obesity crisis – dubbed the single-nutrient approach – has now run its course.”

“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 for what could happen next,” Assoc. said Professor Macia.

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