Development of prebiotics and prebiotics

Consumers around the globe are now more aware of the relation between nutrition and good health. This has led to a number of scientific studies identifying food and food components that have specific health benefits. Functional foods are defined as foods that, in addition to nutrients, supply the organism with components that contribute to the cure of diseases, or to reduce the risk of developing them (Prado et al., 2008). One of the first countries in the world to recognize the concept of functional foods was Japan. The Japanese government defines FOSHU (Foods for Specific Health Use) as Foods which are expected to have certain health benefits, and have been licensed to bear a label in the product claiming the health effect (Sanders, 1998).

The establishment of a microflora rich in bifidobacteria poses an advantage with respect to maintaining and improving health. In the past two to three decades, one of the main targets of the functional food industry has been the development of products aimed at improving gut health. The idea of manipulating the intestinal microflora in order to prolong life can be tracked down to the early part of the twentieth century. In 1907, the Nobel Prize winner Eli Metchnikoff published his book The Prolongation of Life, where he postulated that the long life span of Bulgarian people was due to the consumption of fermented milks that contained the microorganism Bacillus bulgari- cus, currently known as Lactobacillus delbrueckii. According to Metchnikoff, the consumption of these bacteria would have the effect of eliminating putrefactive bac- teria in the human gastrointestinal tract (GIT). In the same period, the French pedia- trician Henry Tissier discovered the predominance of bifidobacteria in the feces of healthy infants, and postulated their effectiveness in preventing infections (Said and Mohamed, 2006). Experimental work on the effect of ingestion of “beneficial micro- organisms” on human health was carried out in the 1930s, but the results were not clearly positive, and this line of research was abandoned for 40 years.

The term probiotic, from Greek “for life,” was used for the first time by Lilly and Stillwell (1965) to define substances produced by microorganisms which would enlarge the growth phase of other microorganisms. Later, Parker (1974, pp. 366) changed this definition to “organisms and substances that contribute to intestinal bal- ance.” Fuller (1989, pp. 366) eliminated the concept of substances from the definition of probiotics, and substituted it for “live microbial feed supplements which benefi- cially affect the host animal by improving its intestinal microbial balance.” This defi- nition was later extended to include a viable mono or mixed culture of bacteria that will beneficially affect the host when applied to human or animals by improving the properties of the indigenous microflora. Contrarily, Salminen et al. (1999, pp. 109) stated that there are documented health effects of nonviable probiotics and even the cell wall components on some probiotic microbes. This led to the establishment of the following definition: “Probiotics are microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well-being of the host.” This definition introduces a second novelty with respect to the one proposed by Fuller, and it is the beneficial effect of probiotics on human health in general rather than specifically on intestinal health. The most accepted definition nowadays is that given by the World Health Organization as “live microorganisms that, when administered in adequate amounts confer a health benefit to the host” (Araya et al., 2002, pp. 8). Prebiotics have been defined as nondigestible food ingredients beneficially affecting the host by selectively stimulating the growth and/or activity of a limited number of bacteria in the colon and thus improving the host health (Gibson et al., 2004b). Probiotics and prebiotics can be combined in symbiotic preparations (symbiotics). These mixtures beneficially affect the host in different ways. For instance, by improv- ing the survival and implantation of live microbial dietary supplements in the GIT; by selectively stimulating the growth and/or by activating the metabolism of one or a limited number of health-promoting bacteria, and thus improving the host well-being (Hamilton-Miller, 2003).