We’re all partial to a little fast food now and then – I know I am. But do we really think about the effects it has on our bodies? A new study from the University of Bonn has been investigating, and the results are certainly Food for Thought (Pun intended).
Researchers fed mice with a “Western Diet”, one high in fat, salt and sugar but low in fibre, and examined the effect this had on the mice’s immune systems. After a month the mice were shown to have high levels of immune cells in their bloodstreams, a similar increase to what one would expect to see in the aftermath of a bacterial infection.
“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,” says Anette Christ one of the researchers involved in the study. These granulocyte and monocytes are the cells of the immune system that are particularly involved in the nonspecific inflammatory response that occurs in the first few days after an infection, before a response specific to the infection can be mounted.
After a month the mice were shown to have high levels of immune cells in their bloodstreams
Worryingly, these inflammatory responses can lead to the development of vascular disease, type 2 diabetes, or trigger the build-up of plaque in the arteries (called atherosclerosis) which can lead to stroke or heart attack.
These inflammatory changes clearly have a marked impact and further genomic studies showed activation of certain genes in immune progenitor cells occurred as a result of the changing diet. Furthermore, after the mice subjects were moved off of the western diet the immune response deteriorated but the genetic reprogramming remained, meaning that inflammation, and all the problems associated with it, could be triggered more easily in the future.
“It has only recently been discovered that the innate immune system has a form of memory,” explains Prof. Dr. Eicke Latz, “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.” In the mice this reaction was not triggered by an infection, but by the unhealthy diet they were subjected to. Investigating further the researchers were able to identify this fast food sensor in the immune cells. They examined blood samples from 120 subjects. In those subjects which displayed a strong memory effect they were able to show the involvement of “inflammasomes”, intracellular signalling complexes that detect harmful agents and release messengers that trigger the inflammatory immune response. How exactly the inflammasome detects and responds to the western diet is still being investigated.
The addition of the western diet also changes the way that genetic information is packaged. DNA is usually stored wrapped tightly around proteins called histones, thus many tightly bound areas of DNA are simply unreadable. Unhealthy eating causes changes in histone binding, causing some normally hidden areas of DNA to be revealed, like a loop of string being pulled out of a tightly knotted ball. Scientists call these changes, which affect genetic activity without altering the DNA code epigenetic changes. “The inflammasome triggers such epigenetic changes,” says Latz. “The immune system consequently reacts even to small stimuli with stronger inflammatory responses.”
THE INNATE IMMUNE SYSTEM HAS A FORM OF MEMORY.
Bad diet choices can then have a significant impact on overall health, and it shows. Individuals born today will be the first generation in recent centuries to have a shorter average lifespan than their parents, this is due in large part to the effect of unhealthy diets and lack of exercise.
“These findings therefore have important societal relevance,” Latz commented “The foundations of a healthy diet need to become a much more prominent part of education than they are at present.”
So maybe think, next time you head to McDonald’s or order Dominoes, about the effect it could be having on your body and just remember that, while complete abstinence may not be necessary, you can certainly have “too much of a good thing”.