Diets high in milk fat, like the kind found in many junk foods, may be contributing to the rapid increase in inflammatory bowel diseases by encouraging the growth of “bad” intestinal bacteria.
Researchers from the University of Chicago, writing in the journal Nature, studied the effects of different diets on mice that were genetically modified to be more likely to get ulcerative colitis.
Over the past century, inflammatory bowel diseases—like colitis and Crohn’s disease—have increased rapidly, with as many as 1.4 million people in the U.S. affected, according to the Centers for Disease Control and Prevention.
In the study, 60 percent of mice that ate diets high in saturated fats—derived from milk fat—developed colitis after six months, compared to less than a third of mice eating meals low in fat or high in polyunsaturated fats. In addition, the damage to the intestines was much greater in mice on high milk fat diets.
Researchers also found that eating milk fat increased a rare gut bacterium, Bilophila wadsworthia, to about six percent of the total bacteria. This “bad” bacterium makes the bowel more permeable, which allows the cells of the immune system to pass through and cause tissue damage.
While the study was done in mice, it provides some evidence of how Western diets can push people with a genetic risk into developing inflammatory bowel diseases.
Researchers are now testing whether the delicate balance of gut bacteria can be “re-shaped” without “significantly affecting the lifestyles of individuals who are genetically prone to these diseases.”