Prebiotics and Probiotics
Functional foods are generally described as foods that provide some health-benefits beyond traditional nutritional values. For example, probiotics and/or prebiotics may be added to foods to increase functionality.
The Greek translation of Probiotic is “for life.” A probiotic is a microorganism in a food or supplement containing live microorganisms that are present in sufficient numbers to actively enhance consumers’ health by improving the balance of microflora or microorganisms in the gastrointestinal tract. Today probiotic bacteria such as Lactobacillus and Bifidobacterium are added to fermented foods and other foodstuffs (Aubertin, 2001).
Yogurt is the most familiar product containing beneficial microorganisms. There are, however, other foods that may contain added probiotics, such as sour cream, fruit juices and buttermilk. Fermented foods, such as cheese and sauerkraut, which contain beneficial bacteria, have been a part of the human diet for centuries. Probiotics are also available in tablet, spray, capsule, or powder forms.
Probiotics must be able to survive the aerobic condition of the product in which they are contained, as well as the acidic condition of the stomach. They must also be able to survive the bile levels and pancreatic secretions into the small intestine. (Shah, 2001)
Probiotics may have a number of benefits. Certain probiotics have lactase activity, which is needed to properly digest lactose or milk sugar. For example, people that are lactose-intolerant may be able to eat yogurt that contains organisms that produce lactase enzymes. (Guo, 2001)
Probiotics may also help keep the intestinal tract more acidic, making it difficult for disease causing organisms or pathogens to persist. Scientists agree that bacteria compete for nutrients in the intestinal tract so if probiotics are present in abundance the more virulent organisms may be crowded out.
The immune system may also be stimulated by probiotics. Studies in children suggest that probiotics can help repress infections and allergic responses. (Guo, 2001)
Probiotics may reduce antibiotic-associated infections and diarrhea. Diarrhea is a common side effect of antibiotic treatment. Antibiotics can destroy both good and bad microorganisms in the intestinal tract. A number of probiotics show promise in alleviating antibiotic related diarrhea.
Other health benefits of probiotics, which have been documented or indicated, include suppressing colon cancer, preventing vaginitis, reducing serum cholesterol, improving bowel regularity and maintaining remission in inflammatory bowel disease.
Prebiotics are nondigestible or partially digestible food ingredients that beneficially affect the host (consumer) by selectively stimulating the growth and/or activity of one or more of a limited number of bacteria in the colon, and thus improve host health. (Gibson & Roberfroid, 1995; Schrezenmeir & Vrese, 2001; Gibson et al., 2004) Individual prebiotics may stimulate the growth and/or activity of some indigenous probiotics but not others.
Prebiotics are not digested by human enzymes and therefore have a low caloric value and are efficiently used in low calorie (energy) foods. Because of their non-digestibility prebiotics show fiber-like properties, mainly stool bulking. In this perspective prebiotics are efficiently used to increase stool frequency and to treat constipation. (Kleessen et al., 1997; Den Hond et al., 2000)
The benefits of probiotics are dependent on their viability, growth, and metabolic activity, which can be maximized by prebiotics. Products containing both probiotics and prebiotics are called synbiotics. In certain synbiotic applications, with careful selection of the appropriate strain in combination with the right prebiotic, the functionality of the probiotic can be enhanced by the prebiotic. Other synbiotic applications aim to combine the functionally of both the pre- and probiotic compound or even achieve synergistic effects of combining both. Food ingredient suppliers are now making it easier to add probiotics and prebiotics to foods and beverages by offering blends of synbiotics with the right proportion of pro- and prebiotics to obtain the desired beneficial health effects, as well as improved survival of the live strain.
Selected Examples of Prebiotics
A number of food ingredients have been shown to be prebiotics. These include lactulose, lactitol oligofructose (and sc-FOS), inulin and galacto-oligosaccharides (GOS), tagatose, isomaltooligosaccharides, polydextrose, and digestive resistant maltodextrin. (Gibson et al., 2004)
Inulin and oligofructose are well-documented prebiotics. They selectively stimulate bifidobacteria and lactobacilli in the gut at the expense of pathogenic bacteria such as clostridia and coliforms. In total, 9 interventional human studies, some of them with more than one type of treatment, have been performed and published on inulin and/or oligofructose from chicory as the only active ingredient, to demonstrate their prebiotic effect. more…
The effect of lactitol on the intestinal flora has been extensively studied both in vitro and in vivo. In vitro studies show that lactitol stimulates the growth of Lactobacillus spp. andBifidobacterium. The growth of proteolytic bacteria such as Enterobacterium and Enterococcusis inhibited. (Yuki et al., 1999; Kontula et al., 1999; Kitler et al., 1992; Felix et al., 1990).more…
- Tagatose alters the composition and population of colonic microflora. Both changes in microbial population density and species were observed. Pathogenic bacteria were reduced and specific beneficial bacteria (e.g., lactobacilli) were increased. Tagatose is highly butygenic; about 50% of the short chain fatty acids (SCFA) produced are butyrate.
Clinical studies have shown that polydextrose increases the proportion of Bifidobacterium in the colonic microflora. The shift towards saccharolytic fermentation is also evidenced by reduced colonic pH, increased butyrate production and a reduction in branched short chain fatty acids. more…
Digestive resistant maltodextrin (DRM) has been shown to increase fecal concentrations of beneficial bacteria, including bifidobacteria, in dogs. (Flicklinger et al., 2000). In vitro studies of cecal contents of rats show that short-chain fatty acids are generated in the presence of DRM and further studies on rats show that DRM to prevent intestinal mucosal atrophy occurring due to the long term administration of enteral nutrition (Ohkuma & Wakabayashi, 2001).
Labeling Products Containing Probiotics or Prebiotics
Fifty-three percent of Americans say they want more information on “active cultures,” but only 9 percent are familiar with the term probiotics. Nonetheless, the probiotic market is the world’s largest segment of the functional foods and beverages market. (Sloan, 2004) Products include dairy drinks and desserts, yogurts, bakery mixes, cakes and bread, table spreads and other products containing “gut-healthy” bacteria. Prebiotics like inulin and oligofructose are used in a large variety of products to support and increase the indigenous (naturally occurring) bifidobacteria and to support added microorganisms (probiotics).
Balance is a common theme on products containing pre- and probiotics. Phrases such as stimulates digestion, boosts immune system, restores intestinal flora, strengthens bodies natural defense, for well-balanced microflora, reduces bad bacteria and maintains a healthy digestive system are found on such products. Some products actually name the probiotic in the product, such a Bifidobacteria, lactic acid bacteria and bilact cultures – or state “with probiotics” respectively “with prebiotics” or “prebiotic”.
Examples of probiotic products currently available and labeled accordingly include:
Sweden-based Skane Dairy’s ProViva fruit drink labeled “ProViva reduces the build-up of gas in the stomach.” (This product was awarded Europe’s first health claim for a probiotic product.)
Group Danone is marketing in the U.S. DanActive “daily dose” drinks sold in 100 ml. mini-bottles, labeled “DanActive. Immunity. Helps Naturally Strengthen Your Body’s Defense System.” The product also claims to help “maintain the balance of your intestinal flora.” (Sloan, 2004)
On the prebiotic product side is Litesse®. The sugar-free polydextrose has a low glycemic load and is suitable for products aimed at diabetics and the health and wellness market.
The Institute of Food Technologists assembled an Expert Panel on Functional Foods. The Panel identified a number of areas requiring change to further encourage the development of functional foods. (Clydesdale, 2004) Examples of recommendations considered critical are:
- Modify the current definition and application of the term “nutritive value.”
- Allow product labeling and health claims to accurately reflect the scientific data without triggering drug status.
- Develop incentives for companies to invest in functional foods research and development.
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