Oligosaccharides are an odd-sounding group of carbohydrates that are gaining attention for their numerous roles in promoting and protecting human health. Researchers have reported beneficial effects on constipation, mineral absorption, lipid metabolism, glucose metabolism and immunomodulation, among others.
Many of these benefits are directly linked to the digestion-resistant nature of oligosaccharides in the human body. Interestingly, certain enzymes may produce oligosaccharides from ingested starches and sugars when consumed with a meal.
Oligosaccharides consist of short chains of sugars, generally two to ten sugars in length, placing them between simple sugars and polysaccharides like starch. While the name is still largely unfamiliar to consumers, these compounds are being added to many food and supplement products and include inulin, oligofructose, FOS (fructo-oligosaccharides) and GOS (galacto-oligosaccharides). They are natural constituents of many plants and vegetables including chicory root, Jerusalem artichoke, onions, legumes, wheat, barley and asparagus.
Human breast milk is another source of oligosaccharides; it provides a rich supply of GOS that has been shown to support a healthy immune system in infants. With their mildly sweet flavor and low glycemic index, oligosaccharides are gaining interest for use as functional foods.
In the human diet, carbohydrates are generally considered as either digestible or indigestible. Digestible carbohydrates include starches, sucrose and lactose. Indigestible carbohydrates include cellulose, stachyose and other fibers. Oligosaccharides that are resistant to digestion are another form of dietary fiber. The human digestive tract lacks the enzymes necessary to break down fibers, allowing them to pass through the digestive tract and provide many of the health benefits listed above.
Unfortunately, the typical American diet is rich in digestible carbohydrates and often woefully deficient in indigestible fiber. This diet delivers high levels of glucose and fructose with the potential consequences of weight gain and excessive blood sugar absorption. Emerging science associates these conditions with higher risk of digestive problems, obesity, dyslipidemia, type II diabetes, liver disease, cardiovascular disease, and a weakened immune system.
How Oligosaccharides work
Consumption of oligosaccharide-producing enzymes along with meals is one tool that may be beneficial in managing glucose and caloric availability. Oligosaccharide-producing enzymes transform digestible carbohydrates to indigestible forms and offer the advantage of increased fiber.
There are currently two oligosaccharide-producing enzymes with New Dietary Ingredient (NDI) applications on file with the US Food and Drug Administration: transglucosidase and levansucrase.
Like other starch-digesting enzymes, transglucosidase is able to cleave the 1, 4-linkages that hold glucose units together to form starch. However, unlike these enzymes, transglucosidase then links the freed glucose to another substrate via a 1, 6-linkage that is not readily digestible by human digestive enzymes.
The enzyme produces glucose polymers known as gluco-oligosaccharides or GLOS. This effectively removes the transferred glucose from the absorbable pool of sugars and further limits the digestibility of the attached substrate. If it is not digested, it is not absorbed. If it is not absorbed, it reduces glucose absorption as well as the caloric availability. The bound glucose then also contributes to an increased fiber load.
Levansucrase functions similarly to transglucosidase; however, it cleaves the fructose-glucose bond in table sugar and attaches the fructose molecule to another substrate, creating indigestible fructo-oligosaccharides (FOS). The enzyme’s action reduces the availability of fructose for absorption and results in less caloric availability.
Product formulation ideas
Transglucosidase and levansucrase offer interesting opportunities for digestive product formulations. Combinations with each other may be especially applicable for a focused carbohydrate-management application. Including other digestive enzymes may increase the availability of sucrose and starch as well as potential receiving substrates. This in turn may further decrease the availability of glucose and fructose for absorption.
One interesting area of research on oligosaccharides is their ability to function as prebiotics. Prebiotics are defined as non-digestible carbohydrates that stimulate the growth of beneficial microflora in the gut – probiotics. The role of microflora in promoting human health is an area of intense research and has identified benefits for digestion, immunity and mental health as well as the ability to influence lipid and sugar metabolism.
Dietary supplementation of transglucosidase and/or levansucrase may effectively increase the availability of prebiotic oligosaccharides, supporting a healthy balance in the colonic microflora.
The potential health maintenance benefits of the oligosaccharide-producing enzymes makes them a useful tool in the enzyme arsenal, especially for people concerned about blood-sugar management, weight management, fiber intake, and general health management. They also make useful adjuncts to probiotic and digestive-support products.
Danielle Harrison is manger of scientific and regulatory affairs at National Enzyme Company.