Prebiotic (nutrition)

What are prebiotics?

Unlike probiotics, which are living microorganisms, prebiotics are indigestible carbohydrates. These prebiotics stimulate the growth and activity of beneficial bacteria of the intestinal flora.

What is a person’s intestinal flora?

The intestine of an adult human contains approximately 1014 bacteria of more than 400 different species and sub-species, which together weigh between 1 - 1.5 kg. Because bacteria are single-cell organisms and can carry out all essential metabolic activities themselves, the complete intestinal flora can be considered an enormous and complex metabolic organ for the human body. As a result, this "organism" affects our health and well-being.

What are beneficial bacteria in the intestinal flora?

In the large intestine, we can differentiate between beneficial bacteria such as bifidobacteria and lactobacillus and possible pathogenic bacteria such as E. coli, salmonella and clostridium. The latter cannot use the indigestible carbohydrates. If one stimulates the growth of beneficial bacteria using lactulose, they can therefore displace the possible pathogens. Other important functions of a healthy intestinal flora are:

• Growth inhibition of possible pathogenic bacteria
• Positive influence on the activity of the immune system
• Recovery of the intestinal flora after treatment with antibiotics
• Production of digestive enzymes
• Inhibition of viruses (e. g., rota viruses)

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Prebiotics are non-digestible food ingredients that stimulate the growth and/or activity of bacteria to the digestive system and health of the body.[1] They are considered in the category of functional foods.

Roberfroid updated the definition in the 2007 Journal of Nutrutrition (J. Ntr. 137:830S) adding, "A prebiotic is ‘‘a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-being and health.’’ Today, only two dietary nondigestible oligosaccharides fulfill all the criteria for prebiotic classification," those two being fructooligosaccharides and galactooligosaccharides. Use of the term other than in that manner is incorrect, since all oligosaccharides do not fit this definition, i.e. mannanoligosaccharides (MOS). They may confer other positive benefits, but are minimally utilized by the comensural bacteria.

Typically, prebiotics are carbohydrates (such as oligosaccharides), but the definition does not preclude non-carbohydrates. The most prevalent forms of prebiotics are nutritionally classed as soluble fiber. To some extent, many forms of dietary fiber exhibit some level of prebiotic effect.

Function

The prebiotic definition does not emphasize a specific bacterial group. Generally, however, it is assumed that a prebiotic should increase the number and/or activity of bifidobacteria and lactic acid bacteria. The importance of the bifidobacteria and the lactic acid bacteria (LABs) is that these groups of bacteria have several beneficial effects on the host, especially in terms of improving digestion (including enhancing mineral absorption) and the effectiveness and intrinsic strength of the immune system. A product that stimulates (or claims to stimulate) bifidobacteria is considered a bifidogenic factor. Some prebiotics may thus also act as a bifidogenic factor and vice versa, but the two concepts are not identical.[2]

Sources

Traditional dietary sources of prebiotics include soybeans, inulin sources (such as Jerusalem artichoke, jicama, and chicory root), raw oats (see also Raw foodism), unrefined wheat, unrefined barley and yacon. Some of the oligosaccharides that naturally occur in breast milk are believed to play an important role in the development of a healthy immune system in infants, but these are not considered prebiotics, as they do not act through the intestinal microflora.

Prebiotic oligosaccharides are increasingly added to foods for their health benefits. Some oligosaccharides that are used in this manner are fructooligosaccharides (FOS), xylooligosaccharides (XOS), polydextrose and galactooligosaccharides (GOS). Some monosaccharides such as tagatose are also used sometimes as prebiotics.[citation needed]
In petfood also mannooligosaccharides are being used for prebiotic purposes.

Effects

Studies have demonstrated positive effects on calcium and other mineral absorption, immune system effectiveness, bowel pH, and intestinal regularity.[citation needed] Correlations have also been made with other positive health factors, but more research is required.

The immediate addition of substantial quantities of prebiotics to the diet may result in a temporary increase in gas, bloating or bowel movement. It has been argued that chronically low consumption of prebiotic-containing foods in the typical Western diet may exaggerate this effect.[citation needed]

See also
Probiotic

External links
More reading on prebiotics: Food-Info.net on prebiotics and bifidogenic factors
International Scientific Association for Probiotics and Prebiotics

References
^ Gibson GR, Roberfroid MB. Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics. J Nutr. 1995 Jun;125(6):1401-12. PMID
^ Food-Info.net Wageningen University
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