Our body needs different types of food for the various functions, maintenance and growth. Food can be categorized broadly into carbohydrates, proteins and fats. While fats help in long term storage of energy which is not utilized right away, proteins help in building muscles and tissues. It is the carbohydrates that provide us with the energy required to do immediate work as they can be broken down right away into glucose which is utilized by the muscles to provide energy. These in turn are categorized into mono-saccharides(simple sugars), di-saccharides and polysaccharides. "SACCHARIDES" is derived from the greek word sacchar meaning "Sugar" and Poly meaning many sugars put together is basically a many sugared molecule in simple terms. Polysaccharides are polymer carbohydrates made up of many monosaccharides or disaccharides. In simple terms, polysaccharides are complex sugar molecules made up of many blocks of simple sugar. The sugars are held together by the glycosidic bonds. A glycosidic bond is a covalent bond that joins a carbohydrate molecule to another group that may or may not be a carbohydrate. Their properties may vary from their building blocks i.e. the monosaccharides.
If the polysaccharide is made up of same type of monosaccharides, they are called homopolysaccharide or homoglycan, if it is mad up of different types of monosaccharides, they are known as hetero-polysaccharides or heteroglycans. The three common polysaccharides are Starch, Glycogen and Cellulose.
Starches : While Starches are basically glucose polymers they need the enzyme Amylase to be broken down into glucose or to be digested. Plants store glucose in the form of starches.
Glycogen : This is a storage form of glucose which is broken down into glucose when needed by animals and humans.
Cellulose : These are polysaccharides that are the components of plants and are used as building material. They give both shape and structure to the plants. Cellulose cannot be digested by humans and that is the reason we cannot digest grass as it is made up of cellulose. Cows, horses, sheep, goats can digest cellulose because they have symbiotic bacteria in their intestinal tract and it is these bacteria with their enzymes that help in digesting cellulose. Humans still use Cellulose in the form of cotton, paper to make a lot of products which we are all too familiar with.
Chitin : It is a modified polysaccharides that contains Nitrogen. It is derived from glucose. It forms the external skeleton in many animals and is also bio-degradable. These polysaccharides resembles the cellulose in structure and the protein keratin in terms of function. This polysaccharide has a wide use in the agricultural, industrial and medical fields. Chitin has proven great use as a fertilizer and also to increase the immunity among the plants. It is used as a binder in dyes, adhesives and fabrics in the industrial area. It is also used as a surgical thread in the field of medicine because of its ability to dissolve.
Pectin : This is a polysaccharide that forms the primary cell walls of many terrestrial plants. This is an example of heteropolysaccharides. It has various uses in the food industry as it acts as a gelling agent for jams and jellies. It is also used as a food thickening agent and stabilizer in juices, milk.
Arabinoxylans : It is a polysaccharide found in the primary and secondary cell wall of plants i.e. wood and also in the cereal grains. It is a combination of arabinose and xylose.
The food we eat is mixed with enzymes released by the body at various points to help in the digestion of the different types of molecules such as fats, proteins and carbohydrates. While chewing helps in breaking down the carbohydrates into smaller chunks, it is in the stomach followed by the small intestine that the final breakdown of the polysaccharides happens. The acid released in the stomach breaks them down into monosaccharides. The monosaccharides are glucose molecules which are the basic energy providing molecules. The glucose is further broken down in the cells into molecules of ATP - Adenosine Triphosphate. It is only when glucose is broken down into ATP can carbohydrates provide energy that can utilized by the body to do work. While the excess ATP molecules are converted by the liver into glycogen, these can be later broken down to glucose when needed by the body.
Dietary Fiber is a kind of polysaccharide that our body cannot digest. While women need at least 25 grams of fiber per day, men need anywhere from 30-38 grams per day. Dietary fiber is fiber that our body cannot digest to get any nutrients out of it and is the indigestable part that absorbs water as it moves down the alimentary canal and helps in bowel movement. But then not all fibers are dietary fibers. Some of the examples of fibers are, non-starch polysaccharides - cellulose, lignin, chitins and pectins, gum, mucilage. Both fibers and Dietary fibers are present in soluble and insoluble forms. Dietary fiber is only present in plant food which includes nuts, fruits and vegetables. Good sources of dietary fiber are broccoli, bran cereals, beans, peas, whole-wheat breads, grains and cereals. The soluble dietary fiber helps us in preventing constipation, reducing cholesterol levels, treatment of hemorrhoids and diverticulosis. The soluble fibers can be only digested with the help of the bacteria present in our digestive tract. The insoluble fiber is indigestible and helps in bowel movement.
Starch, an example of the storage polysaccharide is produced by all plants. It acts as a major energy reserve in plants and consists of glucose units. Starch is generally made up of 20-25% amylose and 75 to 80% amylopectin. Starch can be digested by hydrolysis with the help of "Amylases" enzymes. Amylases enzymes are present in animals and humans and hence starch can be digested by them. Rice, Potato, Maize and Wheat are all starches used by us as part of our diet. Starch is also used as an adhesive.
Polysaccharides are present in a very high concentration in 2 Asian herbs, Ganoderma Lucidum and Cordyceps Sinensis. While the Ganoderma herb has Ganoderma Polysaccharides, the Cordyceps herb contains Cordyceps Polysaccharides. Both these herbs are proven to improve immune system, which helps in helping with cancer and diabetes.