Butyrate

Adequate amounts of butyrate, a fatty acid, are necessary for the health of the large intestine cells.

Butyrate levels are commonly measured in comprehensive stool analyses and act as a marker for levels of beneficial bacteria.

Source

Butyrate comes from two dietary sources.  First, it is one of the metabolic end products of unabsorbed dietary carbohydrate that has been bacterially fermented in the gut.  Butyrate is the single biggest metabolite of fiber.  Second, the only direct source in the diet is from butter, which contains 3% butyrate.

Fermentation of soy showed higher amounts of propionate and butyrate than did fermentation of other substances.  In another study, the fermentation of gum arabic and apple pectin resulted in a greater short chain fatty acid production than did fermentation of either oat fiber or corn fiber.  The fermentation of gums leads to more proprionate and butyrate production than apple pectin.  Pectin, gum arabic, and guar gum tend to be excellent sources for fermentation by human colonic bacteria.  Oat hull fiber is almost completely resistant to degradation.  Human flora had a hard time degrading corn bran fiber.

Function

Butyrate plays a particularly important role in the colon, where it is the preferred substrate for energy generation by colonic cells.

Butyrate has also been shown to significantly inhibit the growth of cancerous colon cells.  Scientists have found a human gene that stops the growth of cancer cells when activated by fiber processing in the colon.  Although scientists have long linked butyrate to overall reductions in the incidence of colon cancer, the molecular basis of that benefit has remained largely unknown.  Butyrate effects a chemical "unloosening" of molecules that otherwise bind and constrict the activity of the p21 gene.  This gene is responsible for the manufacture of p21 protein, a compound that slows the growth of cancer cells.  A separate study has indicated a possible benefit in breast cancer prevention.