Your gut bacteria produce a compound called butyrate entirely on their own, given the right fuel, and it happens to be the primary energy source for the cells lining your colon, called colonocytes. You never have to eat it directly. Your gut bacteria make it for you, as long as they have fiber to ferment.
What butyrate is
Butyrate is a short-chain fatty acid, a small molecule your gut bacteria produce when they break down, or ferment, fiber that your own stomach and intestines can't handle on their own. Your colon cells run on a different fuel source than most of your other organs. Most tissues get their energy from sugar circulating in your blood. Your colon cells prefer butyrate, made only by your gut bacteria.
How much of colonocyte energy comes from a compound made in-house
Few tissues in your body depend this heavily on a single compound. Butyrate isn't even the most common short-chain fatty acid your gut bacteria make; it's a minority product that ends up doing an outsized share of the work.
Where it comes from
No fiber reaching them means no butyrate gets made, regardless of how healthy the rest of your plate looks that day.
What else butyrate does
Beyond feeding your colon cells, butyrate strengthens the seals between gut cells, calms inflammation by signaling directly to immune cells, and several studies suggest it may play a protective role against colon cancer.[4] It belongs to a broader group of compounds your gut bacteria make for free, sometimes called postbiotics. People with inflammatory bowel disease tend to have fewer butyrate-producing bacteria in their gut, and their colon cells often struggle to use whatever butyrate is around, right when they need it most.
What to do with this
Little evidence shows that a butyrate supplement reaches your colon intact and working the way bacteria-produced butyrate does. Feeding the bacteria that make butyrate is the more reliable path than trying to buy it directly, and it's part of why fiber-focused resets tend to help more than a supplement alone.
Resistant starch is one of the most direct ways to do this, and it's simple to get: cook rice or potatoes, then let them cool before eating. Cooling converts some of the starch into a form your gut bacteria ferment into butyrate. Pair that with fiber-rich foods generally, and your gut bacteria keep making butyrate for you, the way they've been doing all along.
