The immune system reacts similarly to a high-fat, high-calorie diet than to bacterial infection. This is the surprising conclusion of an investigation directed by the University of Bonn (Germany) and collected by the journal Cell. This is a particularly disturbing issue, as unhealthy food seems to make the body’s defenses more aggressive in the long run, even long after switching to a healthy diet.
These long-term changes may be involved in the development of arteriosclerosis and diabetes , diseases related to the consumption of the Western diet.
Western diet trials
Scientists conducted an experiment with mice. For a month they were given the so-called “Western diet”: high in fat, high in sugar and low in fiber , to equate as if a human being ate fast food for a whole month. After this period, the animals developed a strong inflammatory response throughout the body, almost as 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 indicative of the involvement of the immune cell progenitors in the bone marrow,” comments Anette Christ, co-author of the work.
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 status was performed.
“ Genomic studies showed that the Western diet had activated a large number of genes in progenitor cells. The affected genes included those responsible for proliferation and maturation,” explains Joachim Schultze, a co-author of the study.
And it is that fast food makes the immune system quickly recruit a huge and powerful army alerted by the presence of something that it understands as a virus . When the researchers offered the rodents their typical cereal diet for another four weeks, the acute inflammation disappeared. What did not go away was the genetic reprogramming of immune cells and their precursors: even after these four weeks, many of the genes that had been turned on during the fast food phase were still active.
Immune cells have a “fast food sensor”
“Recently it was discovered that the innate immune system has a form of memory”, clarifies Eicke Latz, Director of the Institute of Innate Immunity at the University of Bonn. Thus, after an infection, the body’s defenses remain in a state of alert, so that we can respond more quickly to a new attack.
Experts call it “innate immune training.” In mice, this process was not triggered by bacteria, but by an unhealthy diet. And these effects are long-term.
Activation by a fast food-based diet changes the way genetic information is packaged. Genetic material is stored in DNA, and each cell contains several strands of DNA, which together are approximately two meters long. However, they are usually wrapped around certain proteins in the nucleus and therefore many genes in DNA cannot be read as they are simply too inaccessible.
An unhealthy diet causes some of these normally hidden pieces of DNA to loosen up , similar to a ribbon hanging from a ball of wool. This area of genetic material can be read much more easily. “ The immune system consequently reacts to even small stimuli with stronger inflammatory responses ,” the authors comment.
Dramatic health consequences
“These findings have important social relevance. The fundamentals of a healthy diet must become a much more prominent part of education than they are today. Only in this way can we immunize children at an early stage against temptations. of the food industry “, concludes Latz.
Referencia: Anette Christ et al, Western Diet Triggers NLRP3-Dependent Innate Immune Reprogramming, Cell (2018). DOI: 10.1016/j.cell.2017.12.013
