WEDNESDAY, June 13, 2012 (HealthDay News) -- Certain types of saturated fats common in today's Western diet may change gut bacteria and trigger inflammatory bowel disease in people genetically predisposed to the disorder, according to a new study that looked at this relationship in mice.
Inflammatory bowel disease includes ulcerative colitis and Crohn's disease.
The University of Chicago researchers said their findings help explain why once rare immune-system-related disorders such as inflammatory bowel disease have become more common in the United States and other Westernized nations in the last half-century.
The researchers said their study may shed some light on why many people who are genetically prone to the condition still don't develop it and how certain environmental factors can cause inflammation in those at risk.
Scientists note, however, that research with animals often fails to provide similar results in humans.
Working with mice with characteristics of human inflammatory bowel disease, the researchers found that concentrated milk fats alter the composition of bacteria in the intestines. These changes can alter the fragile truce between the immune system and the complex but largely beneficial mix of bacteria in the intestines.
Harmful bacteria can trigger an unregulated tissue-damaging immune-system response that can be difficult to turn off, according to the study published online June 13 in the journal Nature.
Concentrated milk fats are used widely in processed and confectionary foods, the researchers noted.
The same response was not seen with polyunsaturated fats, which are found in plant-based foods and oils.
"This is the first plausible mechanism showing step by step how Western-style diets contribute to the rapid and ongoing increase in the incidence of inflammatory bowel disease," study author Dr. Eugene Chang, a professor of medicine at the University of Chicago, said in a university news release.
"We know how certain genetic differences can increase the risk for these diseases, but moving from elevated risk to the development of disease seems to require a second event that may be encountered because of our changing lifestyle," he said.
Not much can be done to correct genes that increase a person's risk for inflammatory bowel disease, and getting people to change their diets is often difficult and seldom effective, Chang said.
"However, the balance between host and microbes can be altered back to a healthy state to prevent or treat these diseases," he added. "In essence, the gut microbiome can be 'reshaped' in ... ways that restore a healthy relationship between host and microbes, without significantly affecting the lifestyles of individuals who are genetically prone to these diseases. We are testing that right now."
The Crohn's and Colitis Foundation of America has more about inflammatory bowel disease.