The mechanism of how high-fiber foods really work in the body has been identified by researchers from the Medical College of Georgia. Their study revealed that the fiber physically tears epithelial cells thereby releasing the lubricating mucus.
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 says, 'More mucus is good 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.'
Although the fact that consuming roughage increases mucus production was known earlier and the discovery of frequent cell injury and repair when we eat was found years ago by Dr. McNeil, the new research ties the two together.
Dr. McNeil says, '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. 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.'
However according to Dr McNeil and his colleague Dr. Katsuya Miyake this is an adaptive response and most of these cells repair this damage rapidly while at the same time excrete even more mucus, which provides a bit of cell protection as it eases food down the GI tract.
In 2003, in Proceedings of the National Academy of Sciences, Dr. McNeil revealed proof of his hypothesis that cells with internal membranes use those membranes to repair potentially lethal outer-membrane injuries.
When an outer membrane tear happens calcium just outside the cell rushes in. Although too much calcium is lethal the first entry of calcium causes several of the internal mucus-filled compartments in epithelial cells to fuse together within about three seconds, forming a patch to fix the tear. During this process the compartments expel their contents, as a result of which extra mucus becomes available to lubricate the GI tract.
To test this theory, Dr. Miyake, co-director of MCG Cell Imaging Core Laboratory, initiated work on a method to reproduce cell injuries.
Dr. McNeil says, "Dr. Miyake developed a very potent cutting edge technology involving the two photon laser that allowed us to blast small holes in cells, mimicking what happens in the living animal. It also allowed us to assess in those living cells whether they could reseal, repair the damage and how they might respond biologically, namely in this case, whether they responded by secreting mucus as part of the healing process."
The test revealed that most cells including intact cells in a section of the GI tract did just that. Dr. McNeil says, "Epithelial cells are high-turnover cells but they have a built-in survivability."