If you ever wondered just how a high-fiber diet helps keep you, well, "regular," scientists may have the answer.
Their results suggest that as these bulky foods make their way down the gastrointestinal tract, they run into cells, tearing them and freeing lubricating mucus within.
More mucus is good, says Dr. Paul L. McNeil, cell biologist at the Medical College of Georgia and corresponding author on the study published online Aug. 21 and scheduled for the September print issue of PloS Biology. "When you eat high-fiber foods, they bang up against the cells lining the gastrointestinal tract, rupturing their outer covering. What we are saying is this banging and tearing increases the level of lubricating mucus. It's a good thing."
The fact that consuming roughage increases mucus production was known, and years ago, Dr. McNeil discovered frequent cell injury and repair occur when we eat.
The new research ties the two together.
"It's a bit of a paradox, but what we are saying is an injury at the cell level can promote health of the GI tract as a whole," says Dr. McNeil. Even though epithelial cells usually live less than a week, they are regularly bombarded, in most of us at least three times a day as food passes by. "These cells are a biological boundary that separates the inside world, if you will, from this nasty outside world. On the cellular scale, roughage, such as grains and fibers that can't be completely digested, are a mechanical challenge for these cells," says Dr. McNeil.
But in what he and colleague Dr. Katsuya Miyake view as an adaptive response, most of these cells rapidly repair damage and, in the process, excrete even more mucus, which provides a bit of cell protection as it eases food down the GI tract.
In research published in 2003 in Proceedings of the National Academy of Sciences, Dr. McNeil showed proof of his then decade-old hypothesis that cells with internal membranes
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Contact: Toni Baker
tbaker@mcg.edu
706-721-4421
Medical College of Georgia
22-Aug-2006