Healthy Digestion and Short-Chain Fatty Acids

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:
Short-Chain Fatty Acids

The most important of the short-chain fatty acids produced by colonic bacteria is butyrate.7 The cells lining the interior surface of the human colon convert butyrate into an even smaller fatty acid (acetate) that they can burn for energy and use as a structural building material to seal the junctions between adjacent cells – strengthening the integrity of the colonic barrier and preventing the leakage of any toxins from the colon contents from entering the bloodstream. Without enough butyrate coming from the microbes within the colon, your colon cells go hungry – and the cellular junction can become compromised.

Butyrate and Cell-cycle Control
Butyrate also has another rather amazing function in human colon cells – it helps them remember that they must die, and die on time. This is vital to our ability to continue living. The concentrated exposure of our colon cells to toxins, pesticides and other contaminants entering our body makes these cells highly susceptible to oxidative damage. With enough butyrate to make acetate to seal the body off from the colon contents, your colon cells are better protected from harm.7

However, even in the presence of adequate butyrate, some colon cells do become damaged by free radicals. Fortunately, the biological clock ticking in every colon cell comes to the rescue – each cell is normally endowed with the ability to commit preplanned biochemical suicide (a process called “apoptosis”). Once dead, the cell remnant will detach from the colon lining and will leave with the stool, a process that ensures that colon health remains vibrant. Each cell that is lost this way is replaced by a healthy fresh new cell from the deep layers of the colon lining, and with any luck this cell will live out its life without any problems.7 This normal process of cellular renewal ensures that the healthy integrity of colonic function is maintained.

One of the determinants of the rate of colonic cell renewal is the amount of butyrate available in the colon. Too little and the internal clock slows down, meaning the cell lives longer than it should. This is not a desirable outcome. Healthy tissues are dependent on the vitality provided by the process of cellular regeneration and renewal. A cell that is damaged by free radicals has trouble performing its normal functions and actually can facilitate a decrease in colonic health. This potentially leads to undesirable consequences. Butyrate encourages the normal, healthy lifecycle of colon cells.

Where Does the Butyrate Come From?
Butyrate is not produced by human cells. It is produced by enzymes, secreted by beneficial colonic bacteria; they chemically convert dietary fiber into the short chain fatty acids – most importantly, butyrate. The term “dietary fiber” actually covers a very broad category of large molecules made by plants. These molecules provide both firmness and flexibility to plants, allowing them to bend but not break in a storm. These molecules reach the colon because humans can’t digest them – they pass through the mouth, throat, stomach and small intestine relatively intact.8

Next Best Kept Secrets to Healthy Aging topic:
Probiotics, Prebiotics and Fiber: Dietary Fiber

7. Topping DL, Clifton PM. Short-chain fatty acids and human colonic function: Roles of resistant starch and nonstarch polysaccharides. Physiol Rev 2001;81:1031-1064.
8. Kay RM. Dietary fiber. J Lipid Res 1982;23:221-242.

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