Fast food triggers the immune system making it hyperactive

By Dr. Ananya Mandal, MDJan 16 2018

The immune system has been shown to react to fast foods containing excess salt and calories find researchers. This activation of the immune system to fast foods is similar to its reaction to bacterial infections they add.

The latest study comes from University of Bonn. The results of this new study appear in an article titled, “Western diet triggers NLRP3-dependent innate immune reprogramming,” in the latest issue of the journal Cell.

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The researchers noted that the body responds aggressively to bacterial infections and acts in a similar manner with fast food consumption. The defenses become more aggressive with time when a person takes fast foods. This is a form of inflammation where the immune system is always on the overdrive. The problem remains even after the body has switched over to healthier diets, the researchers find. This stimulation of the immune system and inflammatory reactions has been linked to several diseases such as arteriosclerosis and diabetes.

For this study the team of researchers placed some lab mice on “western diet” or a diet of fast food with excess fat, sugar and salt and low amounts of fibre. They noted that the mice showed increasing inflammatory reactions within their bodies. The inflammation was similar to a response to a bacterial infection. Anette Christ, postdoctoral fellow in the Institute of Innate Immunity of the University of Bonn said that the “unhealthy diet” was responsible for producing certain immune cells in the mice’ blood.

These included granulocytes and monocytes. The bone marrows of the mice that produced the immune cells seemed to have been stimulated by the diet. The team analyzed the changes in the bone marrow of the mice of healthy diet and those on the western diet. The functions of the bone marrow as well as their activation states were noted. Prof. Dr. Joachim Schultze from the Life & Medical Sciences Institute (LIMES) at the University of Bonn and the German Center for Neurodegenerative Diseases (DZNE) explained that the bone marrows were subjected to genomic tests to look at the genes that had been activated by the inflammatory status. He added that the results indeed revealed that the genes of the bone marrow had been altered to produce more immune cells. He said that the fast food actually stimulates the early and rapid maturation of the immune cells. Thus an army of white blood cells are created within a short period of time within the body in response to fast foods.

The researchers then withdrew the unhealthy diet in the mice and gave them a normal healthy cereal diet. The blood levels of the immune cells reduced and became normalized. What did not change was the genetic reprogramming of the bone marrow that the initial inflammation had already caused. Four weeks of healthy diet failed to change the alertness of the immune system or the overdrive on inflammation they concluded. Prof. Dr. Eicke Latz, Director of the Institute for Innate Immunity of the University of Bonn and scientist at the DZNE called this an immune system “memory”. Experts tem this “innate immune training” where the body is alert for new infections or attacks. In this case the process was not stimulated by a bacterial infection but an unhealthy diet.

As a next step the scientists checked on humans from the blood cells of 120 participants. They noted that some of these persons were genetically programmed to have the immune system memory that could be triggered with unhealthy diet. The actual molecular mechanisms are being explored. What is clear is that this state of inflammation overdrive can lead to health problems such as diabetes and atherosclerosis leading to heart attacks and strokes.

Reference: https://www.uni-bonn.de/en and "Western diet triggers NLRP3-dependent innate immune reprograming; Cell", 11.1.2018, DOI: 10.1016/j.cell.2017.12.013