Isomaltooligosaccharide

Isomaltooligosaccharide (IMO) is a mixture of short-chain carbohydrates which has a digestion-resistant property. IMO is found naturally in some foods, as well as being manufactured commercially. The raw material used for manufacturing IMO is starch, which is enzymatically converted into a mixture of isomaltooligosaccharide.

Chemistry
The term “oligosaccharide” encompasses carbohydrates that are larger than simple di- or tri-saccharides, but smaller than polysaccharides (greater than 10 units). Isomalto-oligosaccharides or IMO, specifically, are glucose oligomers with α-D-(1,6)-linkages, including among others isomaltose, panose, isomaltotetraose, isomaltopentaose, nigerose, kojibiose, and higher branched oligosaccharides. While human intestinal enzymes readily digest α(1,4)-glycosidic bonds, α(1,6)-linkages are not easily hydrolyzed and exhibit a digestion-resistant property, therefore, partially digest in the upper gastrointestinal tract.

Isomalto-oligosaccharides are normal components of the human diet that occur naturally in a number of fermented foods, including rice miso, soy sauce, and sake. Isomaltose one of the α(1,6) linked disaccharide components of IMO, has been identified as a natural constituent of honey. IMO is a sweet-tasting, high-density honey like syrup in appearance which could be spray dried into powder form.

Manufacturing
For manufacturing IMO on commercial scale, food industries using variety of starch processed from different cereal crops like, wheat, barley, corn, pulses (peas, beans, lentils) oats, tapioca, rice, potato and other starch sources, thus providing a wide range of flexibility to consumers who might have allergenic concerns or hypersensitivity toward certain type of cereal crops. The manufacturing process controls the degree of polymerization (dp) and the α(1,6) linkages to ensure consistent high quality of isomalto-oligosaccharide from alternate 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 human intestine. These α(1,4) glycosidic linkages are further enzymatically converted into more digestion-resistant α(1,6) glycosidic linkages, that consequently confers the property of “iso” linkages between the glucose moieties of oligosaccharides and thus in formation of Isomalto-oligosaccharide (IMO). The majority of oligosaccharides found in IMO consist of 3 to 6 monosaccharide (glucose) units linked together; however, disaccharides, as well as longer polysaccharides (up to 9 glucose units) also are present. The disaccharide fraction of IMO mainly consists of α(1,6) linked isomaltose, while maltotriose, panose, and isomaltotriose make up the trisaccharide fraction. Mixture of Isomaltotetraose, isomaltopentaose, maltohexaose, maltoheptaose, and small amounts of oligomers with 8 or more degrees of polymerization comprise the remaining oligomers in IMO. It should be noted that longer oligomers do not have 100% of α(1,6) linkages, but the degree of α(1,4) and α(1,6) linkages are might be variable.

Health benefits
IMO is a multifunctional health molecule which exerts positive effects on human digestive health. There are numerous scientific papers available about the role of IMO as prebiotic, least flatulence (i.e., generating least gas), low Glycemic index,  and Anti-caries Activities.

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". Many oligosaccharides are not digested in the small intestine and instead are fermented by Bifidobacterium species in the human colon, thus enhancing their proliferation. In this respect, fermentable oligosaccharides may be considered as prebiotics. Studies conducted to assess the digestibility of IMO mixtures indicates that the oligosaccharides are at least partially fermented by bacteria in the colon. Consequently, the un-hydrolyzed and, therefore, unabsorbed portion of an IMO mixture reaching the colon may stimulate the growth of bacterial subpopulations. There are number of published studies confirming the prebiotic effect of IMO including a recent one by the University of Alberta, Canada.

Generally, short chain oligosaccharide, like IMO, which confers prebiotic properties in turn, produced Short-chain fatty acid (SCFA) like acetate, propionate and butyrate as end-products of fermentation. These molecules decrease the intra-luminal pH, directly inhibiting the growth and activities of harmful micro-organisms, and contribute to stimulation of the growth of Bifidobacteria, which compete with the enteropathogens for nutrients and epithelial adhesion sites. Uses of IMO by infants & children are equally beneficially in term of improved digestive health similarly as observed in the case of elderly population.

Dental caries are caused by insoluble glucan gums forming on the surface of teeth (plaque), and the formation of acids under this plaque which attacks the tooth enamel. Studies with animal models showed that IMO in place of sucrose reduces the amount of plaque formed and also reduces the amount of enamel attacking acids formed, therefore, acts as an anti-caries ingredient

The reported Glycemic Index (GI) for IMO is 34.66±7.65 which represents a low GI. Consumption of IMO effectively improved bowel movement, stool output and microbial fermentation in the colon without any adverse effect in elder peoples.

The American Association of Cereal Chemists (AACC) defined soluble fiber as “the edible parts of plants or similar carbohydrates resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the large intestine”.

Dietary fibers are the indigestible portion of plant foods that move food through the digestive system, absorbing water and making defecation easier. Dietary fiber consists of many other plant components such as dextrin, inulin, lignin, pectin, beta-glucans and resistant-oligosaccharides. For a dietary substrate to be classified as a Fiber, following criteria are required;
 * The substrate must be resistant to digestion & absorption in upper GI tract
 * It may undergo partially or completely fermentation by bifidobacteria or do not ferment at all
 * Fermentation may results in SCFA that metabolize in liver and confer many physiological benefits to the host
 * Induce bulking effect in feces

Since IMO consists mainly of 3 to 7 glucose units linked together mostly by digestion-resistant α(1-6) linkages with having a prebiotic effect as well as exhibiting the properties of retaining moisture, producing bulking effect and helping moving the stool forward, it is considered a type of dietary fiber.

Usage
IMO is finding global acceptance by food manufacturers for use in a wide range of food products. It’s gaining recognition as a robust food and beverage functional ingredient and getting acceptance with food formulators and food & beverage manufacturers, for use in a broad spectrum of applications in food products categories with the beverage market and bakery/nutrition bar markets leading the way. Although, in USA, most of the food companies are using IMO as a source of dietary fiber, IMO is also being used as a low calorie sweetener in variety of foods like bakery products, confectionaries, cereal products, sweets and related. Being about 50% as sweet as sucrose (sugar), IMO cannot replace sugar in one-to-one ratio. However, as a natural food ingredient and having a high tolerance with the least side effects compared to other oligosaccharides of the same class, this carbohydrate molecule is receiving growing attention by the food manufacturers and formulator across North America as well as in Europe.

Side-effects
Generally, all the digestion-resistant oligosaccharides have more or less adverse effects when consumed in amounts greater than permissible levels. IMO also have certain side effects when consumed in excess amounts. The maximum permissible dose of IMO that does not cause gastric disturbance is estimated at 1.5 g/kg body weight, which is higher than for any other sugar substitute. However, the U.S. Food and Drug Administration (FDA) has recommended the intake level for IMO at 30 g/day. This level is expected to be well tolerated with no or least side effects. In case of higher dosage (e.g., greater than 40 g/day), there is a possibility of gastrointestinal symptoms like flatulence, bloating, and soft stool or in some cases diarrhea.

Regulatory information
IMO and other oligosaccharides have long been approved in Asia, e.g., in China & Japan. In Japan, IMO is on the Foods for Specified Health Use (FOSHU) ingredient list for more than 10 years. Over 50% of the FOSHU foods in Japan in 2002 incorporated oligosaccharides as the functional component reported a list of 64 FOSHU products for gastrointestinal health that contain oligosaccharides/prebiotics. The list contains numerous food types and products including: Soft drinks, frozen yogurt, confectionary products, sweeteners, cookies, coffee drink mixes, bread, tofu, chocolate, soup mixes and other beverages. In North America, although, IMO had been imported into United States for last few years, but never had actually been manufactured or formally approved by FDA until early in 2009, when a Canadian based company, BioNeutra, received FDA-GRAS notification for IMO, and then later on in late 2009, the same company received Health Canada approval for IMO. European Food Safety Agency (EFSA) recently approved the safety of this compound in human consumption and authorized the sale of IMO in European countries.

Commercial availability
IMO is being commercially manufactured mostly in China and Japan for last many years. However, most of this product is either being consumed locally or exported out to neighboring Asian countries. In Japan, Meiji Diaries (Meiji Food Company) is one of the biggest IMO producers. IMO is being marketed by several trade names like IMO-900, IMO-800, etc. Being a novel food ingredient, there wasn't any producer of IMO in North America and Europe, until recently when BioNeutra Inc. started to manufactured this product with the trade name of VitaFiber-IMO. Some other US based companies have already been engaged in producing other kinds of oligosaccharides, like GOS, FOS, XOS, etc.