Scientists have discovered a possible way in which high fat
diets might lead to inflammation in the gut.
Working with mice and zebrafish, researchers at Imperial College
London discovered that cholesterol, a component of fatty foods,
triggers an inflammatory response in the cells lining the gut and
impairs the movement of food through the gut.
Some patients with inflammatory bowel disease report that eating
fatty food can worsen their symptoms, although this has not been
confirmed in studies. The new findings could explain how this
effect might occur.
Professor Maggie Dallman of Imperial who led the study said: "In
humans, inflammation in the gut is associated with a number of
conditions that cause pain and discomfort, such as irritable bowel
syndrome. The relationship between these conditions and diet is
poorly understood, so we were interested in exploring how fatty
diets might cause inflammation.
"We studied zebrafish because they have similar immune systems
to mammals, and their guts have a similar architecture. They are
also translucent, which makes it easy to study what's happening
inside their bodies. We also studied mice to confirm that the
effects are similar in mammals."
The researchers found that feeding the animals cream or butter
caused acute inflammation in the gut lining.
They then showed that this was directly caused by cholesterol
binding to a protein found on the epithelial cells that line the
gut. The response was also dependent on signals from particular
microbes that live in the gut.
After 10 days on a high cholesterol diet, the waves of muscle
contraction and relaxation that push food through the intestine
were impaired. In humans, this effect is a common symptom of
gastro-intestinal disorders, such as irritable bowel syndrome.
Study author Fränze Progatzky, also from Imperial, said: "What's
surprising about our findings is that the initial response to
cholesterol occurs not in immune cells, but in the cells of the gut
lining. We plan to research these effects further and investigate
their possible role in human disease."
The paper, Dietary cholesterol directly induces acute inflammasome-dependent
intestinal inflammation, is published in Nature
Communications.