Fast food may make immune system more aggressive: Study

The unhealthy high-fat and high-calorie diet led to an unexpected increase in the number of certain immune cells in the blood, researchers found. (Source: Thinkstock Images)

Junk food can make the body’s defences more aggressive in the long term, according to a study which found that the immune system reacts similarly to a high-fat and high-calorie diet as to a bacterial infection. Even long after switching to a healthy diet, inflammation toward innate immune stimulation is more pronounced. These long-term changes may be involved in the development of arteriosclerosis and diabetes, diseases linked to Western diet consumption, researchers said.

Scientists from University of Bonn in Germany placed mice for a month on a so-called “Western diet”: high in fat, high in sugar, and low in fibre. The animals consequently developed a strong inflammatory response throughout the body, almost like after infection with dangerous bacteria. “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,” said Anette Christ, postdoctoral fellow at University of Bonn.

“This was an indication for an involvement of immune cell progenitors in the bone marrow,” Christ said. To better understand the findings, bone marrow progenitors for major immune cell types were isolated from mice fed a Western diet or healthy control diet and a systematic analysis of their function and activation state was
performed. “Genomic studies did, in fact, show that the Western diet had activated a large number of genes in the progenitor cells. The genes affected included those responsible for proliferation and maturation,” said Joachim Schultze from the University of Bonn.

When the researchers offered the rodents their typical cereal diet for another four weeks, the acute inflammation disappeared. However, even after these four weeks, many of the genes that had been switched on during the fast food phase were still active.