The term "oligosaccharide" encompasses carbohydrates that are larger than simple di- or tri-saccharides, but smaller than polysaccharides (greater than 10 units).
Isomalto-oligosaccharides (IMO) are glucose oligomers with α-D-(1,6)-linkages, including isomaltose, panose, isomaltotriose, isomaltotetraose, isomaltopentaose, nigerose, kojibiose, and higher branched oligosaccharides.
For manufacturing IMO on a commercial scale, food industries use starch processed from cereal crops like wheat, barley, pulses (peas, beans, lentils), oats, tapioca, rice, potato and others.
The manufacturing process controls the degree of polymerization (dp) and the α(1,6)-linkages to ensure a consistent quality of IMO from different starch sources.
The starch is first converted, by means of simple enzymatic hydrolysis, into high maltose syrup with di-, tri and oligosaccharides (2, 3 or more glucose units) having α(1,4)-glycosidic linkages which are readily digestible in the human intestine.
[6][7][8][9][10] Prebiotics are defined as "non-digestible food ingredients that may beneficially affect the host by selectively stimulating the growth and/or activity of a limited number of bacteria in the colon".
[11] Oligosaccharides that are not digested and absorbed in the small intestine, pass through to the colon where they are fermented by Bifidobacteria, thus enhancing the proliferation of the bacteria.
The oligosaccharides in IMO mixtures are, at least partially, fermented by bacteria in the colon and may, therefore, stimulate the growth of bacterial subpopulations.
[19] Health claims for the various classes of oligosaccharides have been investigated by the European Food Safety Authority (EFSA) and found to be insufficiently substantiated.
Generally, all digestion-resistant oligosaccharides, including IMO, have adverse side effects when consumed in amounts greater than permissible levels.
[22] Higher dosages (greater than 40 g/day), can cause gastrointestinal symptoms like flatulence, bloating, soft stool or diarrhea.