Fibers Rediscovered In Frankfurt
Examing the function of various dietary fibers highlighted at Health Ingreidents Europe.
By Alexandra Pearl
Focusing on functional ingredients, Health Ingredients Europe, Frankfurt, Germany, was this year’s largest gathering for the international ingredients industry. When walking down the hall’s one could easily observe an astounding variety of ingredients, ranging from the familiar products like soya to the more unusual ingredients such as red yeast rice. One product sector, however was of particular interest to most visitors as it promises to cure or prevent many diseases of the digestive tract.
Digestive disorders are a common problem among the elderly population worldwide. In addition, younger people and infants may also suffer from constipation or irritable bowel syndrome. Furthermore, malnutrition may also lead to other disease such as diverticular disease, colon cancer, diabetes mellitus, coronary heart disease and atherosclerosis. Consumers in the 21st century strongly believe that prevention is still the best medicine. Consequently, research conducted in decades past has focused extensively on healthy nutrition. Nutritionists and clinicians agree that dietary fiber has an important effect on our well-being. Even though dietary fiber was originally discovered by the Greeks, the dietary fiber sector was given renewed and special attention at the exhibition as many new types of dietary fibers were presented.
Among some of the new dietary fibers at the exhibition was Caromax™ launched by Nutrinova, Frankfurt, Germany, which is a dietary fiber made from the flesh of carob that not only exhibits a cholesterol lowering effect, but is also said to have antioxidative activity (picture 1). Also highlighted was Vitacell® from J. Rettenmaier & Söhne, Rosenberg, Germany, which is another new generation of dietary fiber that includes wheat fiber, oat fiber, bio-apple fiber, orange and tomato fibers.
What Is Dietary Fiber?
Most people are aware of the role that dietary fiber plays in human health and disease. But not all are aware of the complexities of defining the term itself. Is dietary fiber simply a food compound isolated in the laboratory via an established analytical method? Or should dietary fiber be defined in part by its role in human digestion? The most common definition of dietary fiber is that it consists of the remnants of edible plant cell polysaccharides, lignin and associated substances resistant to digestion by the alimentary enzymes of humans. The Food and Agricultural Organization (FAO) of the United Nation World Health Organization (WHO) states that dietary fibers are constituents of substances of both animal and plant origins that are resistant to hydrolysis by human alimentary enzymes. Many countries accept saccharides of less than DP-10 as dietary fiber (e.g. inulin, oligofructose, Fibersol-2, polydextrose and galactooligosaccharides). However, these shorter chain oligosaccharides do not precipitate as dietary fiber in the standard Association of Official Analytical Chemist (AOAC) method. More importantly however, is that the U.S. Food and Drug Administration , the U.S. Department of Agriculture and the FAO of the WHO accept this method for nutrition labeling purposes.
After a two year debate, the American Association of Cereal Chemists (AACC) has now finally agreed on the following definition for dietary fiber: Dietary fiber is the edible parts of plants or analogous carbohydrates that are resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the large intestine. Dietary fiber includes polysaccharides, oligosaccharides, lignin and associated plant substances. Dietary fibers promote beneficial physiological effects including laxation and/or blood cholesterol attenuation and/or blood glucose attenuation.
Why Is Dietary Fiber Healthy?
All this emphasis surely warrants the question as to why dietary fiber is healthy and essential to our diet. The health care profession explains that the primary mode of action of dietary fiber is on the gastrointestinal tract and that it is important in regulating the rate and site of digestion and absorption and serves as the primary substrate for the microflora normally present in the large intestine. In addition, dietary fiber has the ability to lower plasma and LDL-cholesterol, modify the glycemic and insulinemic response and to protect the large intestine from disease.
Diversity Of Dietary Fibers
As the diversity of dietary fiber is constantly changing, here are some descriptions of some of the dietary fibers currently sold in today’s marketplace.
Inulin: The nutritional properties of inulin have been a matter of interest and intense investigation since the beginning of 20th century. Inulin is a polysaccharide, which occurs naturally in a wide range of vegetables such as chicory, leeks and onions. Many researchers have investigated the use of inulin for the treatment of diabetes.
Fructo-oligosaccharides: Fructo-oligosaccharides (also known as oligofructose) is a fructan like inulin. Both oligofructose and inulin are neither hydrolyzed by human enzymes nor by gastric juices. Like all dietary fibers, they are both partially fermented by colonic bacteria, notably various members of the Bifidobacterium family, but also some other species such as Lactobacillus acidophilus. Regular inulin and oligofructose consumption is said to promote the colon population of these bacteria, while inhibiting the proliferation of other species such as Salmonella, E.coli and Clostridium perfringens. Besides the fact that both inulin and oligofructose are considered prebiotic, both these fructans have shown to induce further interesting physiological and nutritional effects. These effects relate to improved calcium bioavailability, the reduction of risk of developing precancerous lesions in the colon, hypotriglyceridemia and hypoinsulinemia in experimental models. Recently, two human trials have shown that supplementing the daily diet with either 15 grams of oligofructose or 40 grams of inulin causes a significant increase in the apparent absorption of calcium by 26% and 58%, respectively.
A-cellulose: A-cellulose is won from plant material. Cellulose as such is a natural polymer and is the most abundant source of complex carbohydrate. Since it is insoluble with a total dietary fiber content of < 98%, cellulose is indigestible and has zero calories.
Resistant Starch: The term resistant starch is used to describe the fact that this dietary fiber can resist enzymatic digestion in the small intestine and therefore has a positive impact on the health of the large bowel. There are four sub-types of resistant starch and research on the physiological effects for each one is still in progress. The overall physiological effect, which arises from resistant starch consumption, occurs in the small intestine. Research has identified that the resistant starch and dietary fiber content of maize starch rises as the amylose content of maize starch increases. Further studies have shown that resistant starch can effectively lower blood cholesterol and triglyceride levels to reduce postprandial glycemia and improve colonic health.
Soy Polysaccharides: Soy polysaccharides are won from the cell wall material of soy bean cotyledons, which are derived from processing dehulled, defatted soy bean flakes. Its major fractions are non-cellulosic and consist of straight and branched chain polymers containing galactose, arabinose, glucose, uronic acids, xylose,fructose, rhamnose and mannose and about 10% cellulosic components. It is a mixture of cellulosic and non-cellulosic internal cell wall structural components. Soy polysaccharide is a fermentable fiber.
Acacia Fiber: Acacia fiber has a dietary fiber content of 91% and is highly fermentable. Acacia Fiber is extracted from the Acacia tree.
The Future Of Dietary Fiber
How we refer to the new definition and broad range of new dietary fibers available today will also change in which way we refer to the increasingly popular term “functional foods.” The answers to these questions will play an important role in the development, labeling, and marketing of healthy foods in the new millennium.