The immune system can respond to a fast food diet the same as a bacterial infection, according to a 2018 study in mice, raising new questions about the damaging effects of regular trips to burger and pizza chains for our health.
Mice fed for a month the equivalent of a “Western diet” high in saturated fat, sugar and salt, without fresh fruits, vegetables or fiber, have been shown to increase the number of immune cells in their blood, just as they would if they had been affected by a microbial infection.
What’s more, this aggressive state of alarm triggered by fast food could persist for the long haul, the international team of researchers said – this is based on recent research on how our immune systems can remember aspects of battles. past that they have led.
“The unhealthy diet caused an unexpected increase in the number of certain immune cells in the blood of mice, especially granulocytes and monocytes, ” said a member of the team, Anette Christ from the University of Bonn in Germany in 2018.
These white blood cells have directed scientists to certain genes activated by food in mice, genes containing progenitor cells – the types of cells responsible for building an army of immune cells.
This genetic breadcrumb trail is important because it is these progenitor cells that have already been shown to have a kind of memory in the face of biological attacks.
In other words, once the body begins to respond to a fast food diet, returning to a healthy diet may not be enough to completely reverse the changes, and this has implications for our overall health.
This is because when the mice resumed their usual grain diet after a month, the inflammation subsided, but the genetic reprogramming that made the mice more susceptible to future attack remained.
“It was only recently that it was discovered that the innate immune system has a form of memory”, said one of the researchers, Eicke Latz from the University of Bonn. “After an infection, the body’s defenses remain in a sort of alarm state, so that it can react more quickly to a new attack.”
It is normally an infection that produces such a response, but here it was the equivalent of a fast food diet for mice. It means inflammation – and the problems associated with it, like type II diabetes – could be more easily triggered in the future.
So far, we only have evidence of this in mice, although the animals are chosen for their genetic similarity to human beings.
If the same type of reaction occurs inside our bodies, it further proves the link between unhealthy eating and health issues such as type II diabetes, obesity and heart problems, the researchers say.
Scientists have also identified a “fast food sensor” inside immune cells, based on examinations of 120 mice. A signaling system called the NLRP3 inflammasome appears to be the one on the lookout for this type of diet change, although we don’t yet understand how it works.
It’s another warning sign that even as the rate of deadly infections and viruses declines, we are balancing these health improvements with poor diet and lack of exercise, researchers say.
“These results therefore have significant societal relevance”, said Latz. “The fundamentals of healthy eating need to become a much more important part of education than they are now.”
“Children have a choice of what they eat each day. We must allow them to make conscious decisions about their eating habits.”
The research was published in Cell.
A version of this article was first published in January 2018.