Eat foods with soluble fiber and resistant starch since the good bacteria in our guts feed on it and produce butyric acid from it, which the cells of the colon need to repair themselves http://aliciac.hubpages.com/hub/Butyric-Acid-Bacteria-and-Colon-Health. Without it, they will start to atrophy, which I think is quite common nowadays. They say "death begins in the colon" for a reason. Also, use lots of butter since it's a good source of butyric acid, although I'd be interested in seeing a study done to compare the amount of butyric acid in butter to the amount produced by our gut bacteria over the course of say, a day. Here's a list of the amounts of butyric acid in various foods, most of which contain butter http://wholefoodcatalog.info/nutrient/butyric_acid/foods/1/. Butyric acid has many health benefits, which this article talks about http://wholehealthsource.blogspot.com/2009/12/butyric-acid-ancient-controller-of.html.

http://www.youtube.com/watch?v=18K1wQv59h8 a video that claims to show how to make butyric acid, i don't know if it's exactly the same and what else is created in the process..