Fast food makes the immune system more aggressive in the long term
Study shows that even after a change to a healthy diet, the body's defences remain hyperactive The immune system reacts similarly to a high fat and high calorie diet as to a bacterial infection. This is shown by a recent study led by the University of Bonn. Particularly disturbing: Unhealthy food seems to make the body's defences more aggressive in the long term. Even long after switching to a healthy diet, inflammation towards innate immune stimulation is more pronounced. These long-term changes may be involved in the development of arteriosclerosis and diabetes, diseases linked to Western diet consumption. The results will be published in the journal Cell. The scientists placed mice for a month on a so-called "Western diet": high in fat, high in sugar, and low in fiber. The animals consequently developed a strong inflammatory response throughout the body, almost like after infection with dangerous bacteria.
"The unhealthy diet led to an unexpected increase in the number of certain immune cells in the blood of the mice, especially granulocytes and monocytes. This was an indication for an involvement of immune cell progenitors in the bone marrow," Anette Christ, postdoctoral fellow in the Institute of Innate Immunity of the University of Bonn explains. To better understand these unexpected findings, bone marrow progenitors for major immune cell types were isolated from mice fed a Western diet or healthy control diet and a systematic analysis of their function and activation state was performed. "Genomic studies did, in fact, show that the Western diet had activated a large number of genes in the progenitor cells.
The genes affected included those responsible for proliferation and maturation," explains Prof. Dr. Joachim Schultz from the Life and Medical Sciences Institute (LIMES) at the University of Bonn and the German Center for N e u r o d e g e n e r a t i v e Diseases (DZNE). Fast food thus causes the body to quickly recruit a huge and powerful army. When the researchers offered the rodents their typical cereal diet for another four weeks, the acute inflammation disappeared. What did not disappear was the genetic reprogramming of the immune cells and their precursors: Even after these four weeks, many of the genes that had been switched on during the fast food phase were still active.
"Fast food sensor" in the immune cells "It has only recently been discovered that the innate immune system has a form of memory," explains Prof. Dr. Eicke Latz, Director of the Institute for Innate Immunity of the University of Bonn and scientist at the DZNE. "After an infection, the body's defences remain in a kind of alarm state, so that they can respond more quickly to a new attack." Experts call this "innate immune training." In the mice, this process was not triggered by a bacterium, but by an unhealthy diet.