Fast food agitates the immune system and causes long-term systemic inflammationBy cwan | January 29th, 2018
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 defenses more aggressive in the long term. The body’s inflammation response stays super active long after switching to a healthy diet. These long-term changes may be involved in the development of arteriosclerosis and diabetes, diseases linked to Western diet consumption.
The UB 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. Specifically, the unhealthy diet led to an unexpected increase in the number of certain immune cells, which indicates that the genes responsible for regulating the immune response have been triggered.
What this means is that fast food causes the body to quickly recruit a huge and powerful army of immune cells, therefore causing acute inflammation. When the animal is switched to their typical cereal diet, the acute inflammation disappeared. What did not disappear was the genetic reprogramming of the immune cells: Even after these four weeks, many of the genes that had been switched on during the fast food phase were still active.
In addition to the acute inflammatory response, the Western diet also changes the way in which the genetic information is packaged. The genetic material is stored in the DNA and each cell contains several DNA strands, which together are about two meters long. However, they are typically wrapped around certain proteins in the nucleus and thus many genes in the DNA cannot be read as they are simply too inaccessible.
Unhealthy eating causes some of these normally hidden pieces of DNA to unwind, similar to a loop hanging out of a ball of wool. This area of the genetic material can then be read much easier as long as this temporary unwrapping remains active. Scientists call these phenomena epigenetic changes. The inflammation triggers such epigenetic changes that the immune system consequently even reacts to small stimuli with strong inflammatory responses.
These inflammatory responses can in turn accelerate the development of vascular diseases or type 2 diabetes. In arteriosclerosis for example, the typical vascular deposits, the plaques, consist largely of lipids and immune cells. The inflammatory reaction contributes directly to their growth, because newly activated immune cells constantly migrate into the altered vessel walls. When the plaques grow too large, they can burst, leading to blood clotting and are carried away by the bloodstream and can clog vessels. Possible consequences: Stroke or heart attack.
Next time, craving for McDonald’s? Think twice before you bite into that big mac.
Thanks for reading.
Dr. Connie Wan
Journal Reference: Anette Christ, Patrick Günther, Mario A.R. Lauterbach, Peter Duewell, Debjani Biswas, Karin Pelka, Claus J. Scholz, Marije Oosting, Kristian Haendler, Kevin Baßler, Kathrin Klee, Jonas Schulte-Schrepping, Thomas Ulas, Simone J.C.F.M. Moorlag, Vinod Kumar, Min Hi Park, Leo A.B. Joosten, Laszlo A. Groh, Niels P. Riksen, Terje Espevik, Andreas Schlitzer, Yang Li, Michael L. Fitzgerald, Mihai G. Netea, Joachim L. Schultze, Eicke Latz. Western Diet Triggers NLRP3-Dependent Innate Immune Reprogramming. Cell, 2018; 172 (1-2): 162 DOI: 10.1016/j.cell.2017.12.013