Carbohydrates – Classification

Carbohydrates, together with lipids, proteins and nucleic acids, are one of the four major classes of biologically essentialorganic molecules found in all living organisms. Carbohydrates are also known as saccharides, in Greek sakcharon mean sugar or sweetness.

They are widely distributed molecules in plant ans animal tissues. In plants, and arthropods, carbohydrates from the skeletal structures, they also serve as food reserves in plants and animals. They are important energy source required for various metabolic activities, the energy is derived by oxidation. Plants are richer in carbohydrates than animals.


There are a variety of interrelated classification schemes. The most useful classification scheme divides the carbohydrates into groups according to the number of individual simple sugar units.Monosaccharides contain a single unit; disaccharides contain two sugar units; andpolysaccharides contain many sugar units as in polymers - most contain glucose as the monosaccharide unit.

  • Sugars are simple carbohydrates like glucose, fructose and lactose. They cause a rapid rise in blood glucose levels.
  • Starches are complex carbohydrates that are composed of several molecules of glucose. They cause a less rapid rise in blood glucose levels. On the other hand, resistant starch and fiber are not digested or broken down in the small intestine, but these have many positive health effects.
  • Fiber is a non-digestible complex carbohydrate. Our gut does not possess the enzymes needed to break apart the links between sugar units. Undigested fiber travels through our gut and while doing so, provides health benefits.
  • Functions of Carbohydrates in the Body

    Carbohydrates provide energy for the body, enabling metabolism, thus preventing the breakdown of protein as an energy source. Carbohydrates are the preferred source of fuel for the brain, muscle and other organs.

    How Are Carbohydrates Used in the Body ?

    Complex carbohydrates in foods are broken down and converted to simple carbohydrates (glucose) before being absorbed in the blood and used as energy. Metabolism to glucose increases the blood sugar levels, which triggers the pancreas to release a hormone called insulin. This hormone facilitates the entry of glucose into the cells, which convert it to energy.