Short Chain Fatty Acids
Good bacteria are helpful because they make chemicals with helpful properties. One of the most studied classes of healing chemicals are short-chain fatty acids (SCFAs). These include acetate, propionate, and butyrate. Of them, we know the most about butyrate.
Butyrate is a four-carbon fatty acid made by the intestinal flora with four main roles. First, it is the main fuel for the colonocytes – the cells that line the intestinal tract. It is a funny idea but your intestines need food too. Butyrate to your intestinal cells is like salmon, spinach, and blueberries to your body. It makes them strong and healthy. These cells use large amounts of energy in the assimilation and production of nutrients.
Second, butyrate helps control the rate of cell repair. The cells that line the intestinal tract die and get replaced faster than nearly any other cell type in the body. Butyrate gives them fuel to function and regrow new cells.
Third, butyrate regulates the immune system. If new cells don’t grow well, inflammation sets in. Inflammation in the gut leads to local problems like ulcerative colitis and irritable bowel, but it also leads to problems elsewhere in the body like thyroid disease, diabetes, and arthritis.
Fourth, butyrate regulates energy metabolism outside the intestines. It interacts with feedback cycles connecting the gut, liver, and brain. When butyrate is abundant, the body can use energy well, maintain low levels of body fat, and keep the appetite in check. When it is lacking, the risks for weight gain and diabetes increase.
Because of the role played in intestinal cells, butyrate is most widely studied as a way to remedy intestinal permeability and irritable bowel syndrome.