What Are SCFAs and Why Are They Important for Our Health?
Despibe being unable to digest by the body, it doesn’t mean that dietary fiber has no nutritional benefits whatsoever. Once it reaches the colon, dietary fiber will be fermented to produce Short Chain Fatty Acids (SCFAs) and some types of gasses. The main SCFAs produced are acetic acid, propionic acid, and butyric acid. Meanwhile, the gasses include Carbon dioxide (CO2), Hydrogen (H2) and Methane (CH4).
However, before it’s considered one of the most important substance for the body, fiber was a thing people took for granted in the past. At the time it was categorized as a non-nutritive substance, meaning it had no nutritional values but it wasn’t considered dangerous either, due to then-belief that it would just pass through the digestive tract without giving any health benefits.
This view on fiber, however, changed in the 1970s, when studies showed that fiber actually got fermented in the colon as mentioned above, and produced energy. Yes. Though it was indigestible and couldn’t produce sugar which was traditionally known as a source of energy, fiber that got fermented would form SCFAs that got fermented by the body and got metabolized in the liver to be turned into energy.
Depending on the type, dietary fiber produced somewhere between 1 to 2 kkal energy per gram. To make it easier for them to count the calories, researchers agreed to the statement that each gram of fiber produced 2 kkals.
Aside from producing energy, SCFAs can improve metabolism which is beneficial for people with diabetes. SCFAs improve metabolism by preventing lipolysis in adipose tissue, causing fatty acids to decrease and insulin sensitivity to increase (Gao et al., 2009). Additionally, acetic acid which is one of the main SCFAs proced may help provide energy faster than the one provided by sugar. It means, acetic acid helps diabetic people to synthesize less sugar in their liver.
In other news related to reducing blood sugar levels, another type of SCFAs called butyric acid has similar blood sugar-lowering effects but through different mechanism. Initially known as a source of energy for microflora living in the digestive tract, butyric acid has been proven to have a lot to do with carb metabolism.
For example while having high blood sugar level, a diabetic person can’t turn all the sugar into energy. It’s because sugar can only be turned into energy when it exists in the liver of muscles. Here’s where butyric acid plays a role to transport the sugar from the blood to the liver.. The faster the sugar gets to the liver, the faster it’s used up, and the lower its level in the blood (Conforra et al., 2015 ).
Meanwhile, other SCFA called propionic acid has a huge role to lower cholesterol. Similar to how cholesterol-lowering drugs from the class of statin, propionic acid inhibits HMG-CoA reductase, an enzyme that catalyzes cholesterol synthesis.
So, it’s clear how beneficial dietary fiber is for our health. In addition to the benefits of fiber itself, the SCFAs gained from fiber fermentation are good for the body too. So it’s important for us to meet our daily fiber needs as recommended. By consuming 25-30 grams of fiber each day, our body can properly produce SCFAs that help keep the digestive tract healthy, keep us away from certain diseases, and to keep our health in general.
Canfora E.E., Jocken J.W., Blaak E.E., 2015. Short-Chain fatty acids in control of body weight and insuline sensitivity. Nature Rev Endocrin. 11: 577-591.
Gao Z., Yin, J, Zhang J., Ward RD., Martin RJ., Lefevre M., Cefalu WT., Ye J., 2009. Butyrate improves insuline sensitivity and increase energy expenditure in mice. Diabetes 58(7): 1509-17.