Immune System Thinks Fast Food is Bacteria

S u m m a r y :
Your immune system ‘attacks’ the fast food that you consume, responding in the same way as it does to harmful bacteria! These new findings are published in the journal Cell.

Fast Food Affecting the Immune System

Fast food is constantly blamed for the increasing trend of conditions like obesity and diabetes. Numerous studies document the ill effects of its consumption on a regular basis, and a new one comes to highlight the way it affects the immune system (and genetics, while at it!): the findings suggest that the human natural protective mechanisms become more aggressive as a result of exposure to fast food. This is so because the body’s defences treat the unhealthy food rich in fat and calories as harmful bacteria that need to be dealt with. More surprisingly, this rise in ‘aggressiveness’ remains even when the person switches to healthy diets. Also, the authors of the study believe that these changes might be playing a role in the development of arteriosclerosis and diabetes.

Fast Food = Harmful Bacteria

The study was conducted by investigators from the University of Bonn. The research team exposed mice to the typical ‘Western diet’, that is, a diet whose fat and sugar content is high while being low in fibre, for a period of a month. The systems of these mice, eventually, responded with inflammation throughout their bodies, similar in severity to the ones pertaining to infections from harmful bacteria. Normally, when pathogens enter the body, the immune system will launch a series of responses upon detecting them: for instance, immune cells known as granulocytes and monocytes will be released in great numbers in the blood.

“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,” says Anette Christ.

Reprogramming Genes of Immune Cells & Precursors

Immune cells come from cells in the bone marrow, and Christ and her colleagues confirmed, through genomic tests, that “the Western diet had activated a large number of genes in the progenitor cells”.

This shows that fast food triggers the body to put together a strong army to protect itself.

The team proceeded with their experiments by making the mice go back to their usual cereal diet. Four weeks later, the researchers observed that the acute inflammation was gone. However, the genetic reprogramming that had taken place in the immune cells and their progenitors was still there: the genes that were switched on because of the consumption of fast food were still very much active.

The Immune System Remembers

Why do the said genes remain active? According to the researchers, it is all about the memory of the immune system.

“It has only recently been discovered that the innate immune system has a form of memory,” explains Eicke Latz. “After an infection, the body’s defenses remain in a kind of alarm state, so that they can respond more quickly to a new attack.”

So, this process whereby the innate immune system ‘remembers’ a previous attack was not being triggered by bacteria, but simply by fast food, unhealthy food.

A Fast Food Sensor in Immune Cells

Upon examining immune cells from the mice, the researchers found genetic evidence that pointed towards signalling molecules known as inflammasomes. The latter function inside cells where they are meant to identify pathogenic presence together with other harmful substances, and then to release highly inflammatory messengers. So, this means that there exists an inflammasome that recognises that the body has consumed Western diets.

Fast Food Changes Genetic Information Packaging

The long-term effects of fast food on the immune system were also studied. The team found that the Western diet could modify the way in which genetic data was packaged. Genetic information is stored in DNA strands confined to cells, and certain genes are not read because some parts of the DNA are inaccessible. However, these hidden DNA pieces are caused to unwind after exposure to unhealthy diets. This unwrapping is only temporary, but these genes can be read during that time. This type of change is known as epigenetic changes.

“The inflammasome triggers such epigenetic changes,” explains Dr. Latz. “The immune system consequently reacts even to small stimuli with stronger inflammatory responses.”

Fast Food & Diseases

This inflammation can, in turn, speed up the development of heart diseases and diabetes.

The new findings, thus, highlight the disastrous consequences of unhealthy eating. The study authors mention how the latter can contribute to a shortened average life expectancy.

“These findings therefore have important societal relevance,” explains Latz. “The foundations of a healthy diet need to become a much more prominent part of education than they are at present. Only in this way can we immunize children at an early stage against the temptations of the food industry. Children have a choice of what they eat every day. We should enable them to make conscious decisions regarding their dietary habits.”


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