Nowadays human consumption of specific funtional foods known as probiotics and prebiotics represents one of the most common complementary methods, along with a balanced diet, hired for maintaining or restoring balance in the intestinal flora, in case the bacterial homeostasis has been disturbed (Quigley, 2018).
Probiotics, as defined by the Food and Agricultural Organization of the World Health Organization, are “live microorganisms that when administered in adequate amounts confer a health benefit on the host” (FAO and WHO, 2002). The main health benefits of the consumption of probiotics can be summarized to the following points: Probiotics may enhance the resistance of the intestine to pathogenic invasion, restrict the overgrowth of harmful bacteria in the gut, improve the intestinal epithelial barrier function and expedite the response of the human body to possible diseases by provoking the release of appropriate substances (e.g. short-chain fatty acids) (Cremon, Barbaro, Ventura, & Barbara, 2018). There are several yeast and bacterial probiotics, the most common of which are lactobacilli and bifidobacteria and enteroccoci (Vandenplas, 2016).
Extensive research on probiotics has led to the development of other substances called prebiotics, which are selectively fermented ingredients that allow specific modifications concerning the growth and the activity of beneficial bacterial species in the gut (S. H. Duncan & Flint, 2013; FAO and WHO, 2002; Gibson, Probert, Loo, Rastall, & Roberfroid, 2004). The ingestion of prebiotics has the same aim as probiotics, which is the improvement of the host health via alternation of the intestinal flora, though based on a different operating mechanism (Food and Agriculture Organisation and WHO, 2002). More specifically, prebiotics induce the growth of beneficial bacteria that are already present in the human gastointestinal tract, thus enhancing their functionality (B. Duncan, 2013). They can also be consumed in order to maximize the positive health effects of probiotics (Kadlec & Jakubec, 2014). Prebiotics can either be natural plant components or artificially produced substances. The most known ones are nondigestible oligosaccharides (Baquerizo Nole, Yim, & Keri, 2014).