Carbohydrates can be divided into three main categories – starch, sugar, and fiber. Fiber is not digestible; it passes through the body undigested, helps with the body’s sugar usage, and controls the hunger level (Davidson). Consequently, the body is able to digest and absorb only two-thirds of the received carbohydrates. Starch, which is also referred to as polysaccharide, and sugar, which represents disaccharide and monosaccharide, are the digestible types. Both are gradually disassembled into elementary forms in the gastrointestinal system (MacFarlane, 2018). Starch’s dissolution begins in the oral cavity with the help of saliva. Amylase concentrated in saliva and the small intestine launches the digestion process, dissolving starch into monosaccharides and disaccharides. Together with their sugar counterparts, the latter are further digested into simpler, absorbable monosaccharides by the membrane-bound enzymes on the brush border of the small intestine epithelium. The final result of carbohydrates’ digestion is a small selection of monosaccharides – glucose, galactose, and fructose (MacFarlane, 2018). After the dissolution, they are transported along the epithelium of the small intestine and quickly absorbed in the process.
It is difficult to overrate how vital the role of carbohydrates is for the human body. First of all, they represent one of the foundations for the body’s energy stores (Davidson). Stores based on carbohydrates usually serve the body as the immediate energy source. In terms of energy amount, carbohydrates produce four calories per gram; for comparison, the same amount is produced by protein, while fats produce nine calories per gram. Second, glucose obtained after digestion is essential in cells’ functioning. The energy contained within glucose’s chemical bonds secures the organism’s ability to conduct its daily activities.
Davidson, E.A. (n.d.). Carbohydrate. Encyclopædia Britannica. Web.
MacFarlane, N. G. (2018). Digestion and absorption. Anaesthesia & Intensive Care Medicine, 19(3), 125-127.