Prebiotics, Probiotics and Intestinal Function=PURE BLOG POST

Prebiotics were first described in 1995 by Marcel Roberfroid. Conventionally, prebiotics are considered to be non-absorbable, non-digestible but comestible food ingredients that possess the dual qualities of stimulating the growth of beneficial bacteria (commensals) and also enhancing the activity of the aforementioned bacteria; thereby improving the intestinal functions of the host which ultimately leads to an overall improvement of the host’s health. Likewise, probiotics are ingestible food substances which contain beneficial micro-organisms. Ingestion of probiotics delivers the micro-organisms to the intestinal micro-environment where these organisms grow and exert their beneficial effects on the host. Due to their functional characteristics, both prebiotics and probiotics have been classified as the conceptual intermediate between drugs and food, and as such they have been subjected to varying degrees of intermediate level regulatory scrutiny by various healthcare regulatory agencies.

Currently, only two food ingredients are considered to meet the full definition of prebiotics: inulin and trans-galactooligosaccharide. Other prebiotics include lactulose, Mannan Oligosaccharides and fructooligosaccharide. Researchers have classified prebiotics into full-spectrum, long chain and short-chain variants depending on the number of links per saccharide and the duration of fermentation. Fructooligosaccharides are short chain prebiotics which are rapidly fermented in the ascending colon (and to some extent, the right segment of the transverse colon) thereby nourishing the bacteria residing there. This region of the colon is also nourished by probiotics. Rarely do prebiotics nourish the bacteria residing in the transverse colon or the descending colon. Long-chain prebiotics such as inulin are fermented at a slow rate, and as such they tend to nourish the bacteria residing in both the left segment of the transverse colon and the descending colon. Full-spectrum prebiotics such as Oligofructose-Enriched Inulin do nourish the whole spectrum of bacteria residing in the colon.

Acacia gums have the highest content of naturally-occurring prebiotics. Other sources of prebiotics are raw foods such as raw Chicory Root, Jerusalem Artichoke, Dandelion Greens, garlic, leek, onion, asparagus, wheat bran and raw banana. The most common source of probiotics is yoghurt. When prebiotics and probiotics are combined, the resulting combination is described as a symbiotic.

       

Sources of prebiotics

Prebiotics exert their beneficial effects in various ways as explained hereafter. First of all, prebiotics are hydrolyzed by mammalian enzymes into components which can be metabolized by the intestinal microflora. The two most important intestinal bacteria that are nourished by the prebiotics are lactic acid bacteria (lactobacillus) and bifidobacteria. The activities of these two bacteria sub-populations do enhance the rate of intestinal absorption of several minerals (such as calcium, zinc, and magnesium), and they also boost the intrinsic strength and spectrum of the body’s immune system. These bacteria sub-populations do occupy niches that would have otherwise been occupied by pathogenic micro-organisms; therefore they prevent the colon from being colonized by pathogenic micro-organisms. Secondly, bifidobacteria are responsible for increasing the fecal bulk thus enhancing the intestinal motility rate thereby averting constipation. Moreover, the rate of fecal nitrogen excretion is increased as more protein biomass is excreted.  Thirdly, prebiotics have been shown to lower the overall blood lipid levels, by modulating cholesterol synthesis, through their direct enhancement of the enterohepatic circulation. Moreover, an enhanced enterohepatic circulation promotes increased fecal excretion of fatty acids that would have otherwise been used to nourish pathogenic micro-organisms. This, in turn, prevents colonic disorders such as ulcerative colitis and Crohn’s disease, and this ultimately ensures that the integrity of the intestinal regularity is maintained. Studies have also shown that prebiotics do prevent colon cancers.

Probiotics mostly contain lactobacilli, and hence their effects are confined only to the beneficial actions of lactobacilli: enhancement of the intestinal motility rate and prevention of constipation. Moreover, these two actions are less potent and less efficacious when compared to similar actions produced by prebiotics. Therefore, the functional relevance of prebiotics is far more superior to that of probiotics in terms of improving intestinal and immune functions.