Prebiotics

Prebiotics are the booster substance for probiotics.

The definition of a prebiotic was modified in 2017 to "a substrate that is selectively utilized by host microorganisms conferring a health benefit." Gibson 2017

How Prebiotics Function

The complement to probiotics is prebiotics. In order to understand this concept let’s look at how prebiotics function in your gut.

Interestingly, human milk contains small oligosaccharides that are undigestible by newborns. The role of these oligosaccharides in human milk was not at first understood and, in fact, researchers questioned why human milk would contain components unusable by the newborn infant. Scientists provided the explanation when they found that these small oligosaccharides were fueling beneficial bifidobacteria found in the newborn's gut.

Think of human milk as the original synbiotic food containing both probiotic bacteria and prebiotic carbohydrates to fuel bacterial growth. The prebiotic oligosaccharides in human milk are specific to human milk.This model has provided the stimulation and interest of food scientists for adding oligosaccharides to foods and beverages to enhance the growth of beneficial bifidobacteria.

When we eat a snack or a meal, acids and enzymes secreted in our stomach and small intestine digest our food releasing energy and nutrients that are absorbed and utilized by our bodies. But did you know that there are also nondigestible components in food that are primarily plant fibers? In plants, fibers or nondigestible carbohydrates have numerous functions, such as forming the cell wall which gives integrity to the plant.

Consider, for example, celery, where you can see the fibers supporting the stalks. Fibers in plants are resistant to digestive acids and enzymes in your stomach and small bowel. They pass through the upper part of the gut undigested and when they reach the lower part of the gut — the colon — they are still whole. That is why when trying to lower calories in your daily diet, you are advised to increase your intake of plant foods — particularly high fiber vegetables. So you begin chomping on carrot and celery sticks, which fill you up, yet are not fully digested, so you absorb fewer calories. When the nondigestible carbohydrates reach the colon, enzymes produced by the microbiota can digest the fibers to yield fuel and nutrients necessary for their survival.

Gibson GR, Hutkins R, Sanders ME, Prescott SL, Reimer RA, Salminen SJ, et al. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nature Reviews Gastroenterology & Hepatology. 2017;14:491. doi: 10.1038/nrgastro.2017.75.