Prebiotic Substances
Fiber gums are water-soluble and derived from such plants as acacia, carrageenan, guar, locust bean, and xanthan. Usually containing about 85% fiber, these gums help promote the production of large quantities of short-chain fatty acids, which are known to play several beneficial roles, including the development of such intestinal bacteria as Lactobacillus and Bifidobacteria.
Studies have shown that fiber gums do not cause the diarrhea and flatulence often associated with FOS intake, even at high doses. These studies also revealed that, although the fiber gums increased beneficial bacteria, they did not do the same for other strains of bacteria present in the gut.
FOS (fructo-oligosaccharides) is a term used almost universally when describing the prebiotic category. Fructo-oligosaccharides are composed of glucose-terminated fructose chains of 3 to 5 units in length. They are mainly derived from sugar cane via a natural fermentation process. Oligofructose is a mixed FOS compound that is formulated from inulin. It consists of a mixed number of glucose and fructose-terminated chains that vary in length from 2 to 7 units in each chain. Inulin is not a fructo-oligosaccharide because the majority of its chains exceed 10 units.
FOS are resistant to digestion in the upper gastrointestinal tract and are, therefore, able to stimulate the growth of Bifidobacterium and Lactobacillus strains farther down in the large intestine. In vivo, they do not support the growth of pathogens. FOS has shown to increase the absorption of calcium and magnesium and decrease triglycerides. In animal studies, FOS is also showing anticarcinogenic effects, significantly reducing the incidence of colon tumors.
FOS can be found naturally in such foods as Jerusalem artichokes, onions, leeks, some grains, and honey. Because FOS is comprised of sugar molecules, it is mildly sweet -- about 30% as sweet as sucrose. As science continues to validate its health benefits, FOS are increasingly being added to hundreds of products in almost every food category.
Experiments have shown that FOS uptake is significantly reduced when added glucose, fructose, and sucrose are present. Other sugars (mono-, di-, or trisaccharides) were less inhibitory. In addition, when cells were treated with sodium fluoride, iodoacetic acid, or other metabolic inhibitors, FOS transport rates were reduced by up to 60%.
Inulins are a group of non-digestible oligosaccharides belonging to a class of carbohydrates known as fructans. Fructans also include another group called levans. Levans are found in fungi and bacteria while fructans have plant origins.
Inulin-producing plant species are found in several monocotyledonous and dicotyledonous families, including Liliaceae, Amaryllidaceae, Gramineae, and Compositae, especially chicory, onions, leeks, garlic, bananas, asparagus and artichokes. However, only chicory (Cichorium intybus) and Jerusalem artichokes (Helianthus tuberosus) are used to produce Inulin commercially.
Because of their sweet taste and texture, Inulins are added to various foods. They are used as sugar substitutes, fat replacers, as a means of providing texture, stabilizing foam, or improving mouth feel in a wide variety of miscellaneous foodstuffs, including fermented dairy products, desserts, bakery products, spreads, and infant formulas.
Comprised mainly of fructose units, Inulins typically have glucose terminals and most notably stimulate the growth of Bifidobacterium in the large intestine. Because of its longer chain structure, Inulins are thought to ensure longer fermentation times that are needed in the colon.
People are often mistakenly warned to avoid foods containing Inulins because they bind minerals in the small intestine. However, this appears to be a good thing since they are then released into the large intestine, where they are better absorbed than they would have been in the small intestine. This activity is viewed as being beneficial in the prevention of osteoporosis and osteopenia. Inulin also has the ability to hold water, replace fat, and contribute minimal calories.
Isomalto-oligosaccharides are a mixture of glucose and other saccharide molecules. Produced by various enzyme processes, Isomalto-oligosacharides ultimately form several sugar molecules including isomaltose, panose, isomaltotetraose, isomaltopentaose, nigerose, kojibiose, isopanose and other higher branched oligosaccharides. They act to stimulate the growth of Bifidobacterium and Lactobacillus species in the large intestine. They are marketed in Japan as dietary supplements and in functional foods and are being developed in the United States for similar commercial uses.
Lactilol is a disaccharide alcohol analogue of lactulose. Lactilol is used in many countries for treating constipation and hepatic encephalopathy, but not so in the United States. In Japan, Lactilol is also used as a prebiotic because it is resistant to digestion in the upper gastrointestinal tract and is fermented by a limited number of colonic bacteria. However, it is not approved as a prebiotic in the United States either. In Europe, it is used as a food sweetener.
Lactosucrose is a trisaccharide comprised of galactose, glucose, and fructose molecules. It is produced through enzyme action that results in sucrose. Resistant to digestion in the stomach and small intestine, Lactosucrose acts on the intestinal microflora to increase significantly the growth of the Bifidobacterium species.
Lactosucrose is widely used in Japan as a dietary supplement and in functional foods, including yogurt and is being developed in the United States for similar uses.
Lactulose is a semisynthetic disaccharide comprised of lactose and fructose. Lactulose is resistant to human digestive enzymes and is fermented by a limited number of bacteria in the colon, especially Lactobacilli and Bifidobacterium. Currently, Lactulose is a prescribed drug in the United States for the treatment of constipation and hepatic encephalopathy, but it is still in experimentation to see if it is really a prebiotic substance. In Japan, it is marketed as a dietary supplement and for use in functional foods.
Lactulose has exhibited some ability to reduce infectious inflammatory bowel disorders, as well as some colonic tumors. Since it has some ability to improve glucose tolerance and is showing other improvements on carbohydrate metabolism, it is speculated that Lactulose may be helpful in treating Diabetes mellitus. In addition, it has significantly stimulated calcium absorption in postmenopausal women in preliminary clinical work. One cautionary note is that some lactulose preparations contain galactose and would be contraindicated in those who require a low galactose diet. In addition, those who are lactose intolerant should avoid the use of Lactulose, Lactilol and TOS.
Oligofructose is a sweet product derived from native inulin and is about 30-60% as sweet as sugar. It is found on the market as an oligosaccharide because it consists mainly of fructose units with some glucose-terminated chains. It is also available as a mixture with inulin to reduce the amount of non-glucose terminated chains. The unbound fructose chains have prebiotic properties, but with a different fermentation profile than either inulin or FOS. However, it is fermented by a wider variety of probiotic bacteria than inulin. Unlike inulin, oligofructose has the ability to brown, making it a valuable addition to baked products.
Pyrodextrins are a mixture of glucose-containing oligosaccharides derived from starch. Pyrodextrins are resistant to digestion in the upper gastrointestinal tract and have been found to promote the growth of Bifidobacterium in the large intestine and are being developed for the nutritional supplement market place.
Soy oligosaccharides are those found mainly in soybeans, but can also be found in other beans and peas. There are two principal soy oligosaccharides: the trisaccharide raffinose and the tetrasaccharide stachyose. Raffinose is comprised of one molecule each of galactose, glucose and fructose. Stachyose is comprised of two molecules of galactose, one molecule of glucose and one molecule of fructose. Soy oligosaccharides act to stimulate the growth of Bifidobacterium species in the large intestine. They are marketed in Japan as dietary supplements and in functional foods and are being developed in the US for similar uses.
TOS (transgalacto-oligosaccharides) are a mixture of glucose and galactose oligosaccharides. They are produced from lactose via enzyme action obtained from Aspergillus oryzae, which can also be a pathogen. TOS are resistant to digestion in the upper gastrointestinal tract, thereby able to stimulate the growth of bifidobacteria in the large intestine. TOS is marketed in Japan and Europe as dietary supplements and used in functional foods. They are being developed for similar use in the United States. TOS have demonstrated positive effects on calcium absorption and have prevented bone loss in some animal research. In preliminary studies, TOS have shown some ability to lower triglycerides.
Xylo-oligosaccharides are comprised of oligosaccharides containing beta-linked xylose residues. Obtained from enzymatic action, they are marketed in Japan as prebiotics and are being developed for similar use in the United States.
Since Xylo-oligosaccharides resist digestion in the upper gastrointestinal tract, they are able to function in the large intestine to increase the growth of Bifidobacterium species, thus improving gastric function. According to preliminary research, Xylo-oligosaccharides have the potential to improve blood sugar levels and fat metabolism, restore normal intestinal flora following antibiotic, chemo, or radiation therapies, increase mineral absorption and vitamin B production, and reduce intestinal putrification.
