Oligosaccharides are carbohydrates which have three to ten simple sugars linked together. They are found naturally, in small amounts, in many plants and help to feed the beneficial bacteria in the colon but are not metabolised by the body itself. They can be very beneficial because they nurture the beneficial bacteria at the expense of pathogenic bacteria such as E Coli.
Most oligosaccharides have a mildly sweet taste and have certain other characteristics, such as the texture they give to food, which has drawn the interest of the food industry as a partial substitute for fats and sugars in some processed foods as well as improved texture. Because of this, more of the oligosaccharides in non-natural food are synthetically produced. The term fructans refers to two types of soluble fibre, inulin and fructo-oligosaccharides.
Fructo-oligosaccharides
These consist of short chains of fructose molecules and are present in agave, banana, burdock root, chicory root, dandelion root, elecampane, garlic, Jerusalem artichoke, mugwort, leeks, onions, rampion, salsify, wheat, yam and yacon root. They can also be synthesised from the fungus Aspergillus niger acting on the disaccharide sucrose.
Galacto-oligosaccharides
These consist of short chains of galactose molecules and are present in soya beans. They can also be synthesised from the disaccharide lactose.
Mannan-ogilosaccharides
These are normally obtained from the yeast cell walls of Saccharomyces cerevisiae and used in animal feeds to improve gastro-intestinal health, energy levels and performance. Unlike the other oligosaccharides, the mannan type are not fermentable, instead they act upon the immune system and help to eliminate pathogens.
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