A transporter in the colon called SLC5A8 plays an important role in enabling the colon to get the last bit of good out of food before the unusable is flushed away, according to research currently published online as an accelerated communication in the Journal of Biological Chemistry.

In an amazing model of efficiency, good bacteria in the colon produce an enzyme that releases glucose found in plant cell walls, the leftovers of broccoli and other vegetables, fruits and cereals, which cannot be digested in the small intestine. In the oxygen-less environment of the bacteria-packed colon, bacteria ferment this glucose to use for energy which also results in the production of short-chain fatty acids, the preferred nutrients for colon cells.

Medical College of Georgia researchers have found in animal and human cells that SLC5A8 is a final piece of the model, a transporter expressed by colonic cells to absorb the just-produced, energy-packed short-chain fatty acids.

"We used to teach that bacteria produced short-chain fatty acids which are used by colonic cells but it was not known that these cells possessed an efficient active transport system to absorb these fatty acids," says Dr. Vadivel Ganapathy, biochemist, interim chair of MCG's Department of Biochemistry and Molecular Biology and the study's principal author.

The finding that SLC5A8 is the transporter helps clarify why fruits and vegetables are good for you and why antibiotics, which wipe out good bacteria along with bad, should only be taken when absolutely necessary: upset the model and colonic cells get sick and may even become cancerous.

"We do not make the enzyme to digest cellulose; bacteria make the enzyme in the colon," says Dr. Ganapathy. "Therefore, you need to eat dietary fiber to provide the food for bacteria. Otherwise, they are not going to su
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Contact: Toni Baker
tbaker@mcg.edu
706-721-4421
Medical College of Georgia
2-Mar-2004