The term carbohydrates refers to their chemical structure, in which for each atom of carbon there is a molecule of water. For instance glucose, consists of 6 atoms of carbon and 6 molecules of water. Carbohydrates are the most abundant biomolecules found in living organisms on earth. In fact, more than 75% of the dry weight of the plant world is made up of carbohydrates – particularly cellulose, hemicellulose and lignin.
Carbohydrates are an important source of energy, and they include complex carbohydrates, which release energy slowly, and simple carbohydrates that release energy fast. All types of carbohydrates are converted by the body into glucose that is utilised to produce energy, or are converted into glycogen and stored in the liver and skeletal muscle for later use. Carbohydrates are important for cellular and brain function and to fuel physical activity. Dietary fibres are also composed of complex carbohydrates, their role is not to provide energy but to keep a healthy gut and prevent constipation, as well as slowing down the carbohydrate absorption, and also may reduce the absorption of cholesterol.
Furthermore, carbohydrates are very important to life, as they are present in the DNA and RNA molecules. Also, carbohydrates bind to proteins to form glycoproteins, which are essential for cell recognition and signalling, and for cross-linking cells and proteins, such as collagen, to add strength and stability to the tissues.
Glycosaminoglycans are carbohydrates-derived polymers that play a crucial role in intercellular communication. They also interact with a wide variety of proteins, including growth factors and chemokines, which regulate important physiological processes. Proteoglycans are compounds consisting of a protein bonded to mucopolysaccharide groups, present especially in connective tissue. The adenosine triphosphate or ATP is the energy currency of all living organisms. The molecule comprises adenosine that include a type of carbohydrate called ribose, and is attached to three phosphates.
Good sources of simple carbohydrates include various types of fruit, and a good sources of complex carbohydrates include pasta, rise, potatoes and bread. Dietary fibres are a form of complex carbohydrates and are found in whole grains, beans, fruits and vegetables. With regards calories intake, 1 gram of carbohydrates or proteins provides 4 kcalories, whereas 1 gram of fat provides 9 kcalories, which is more than double. In fact, foods high in fat are hypercaloric.
Carbohydrates are a vital energy source to fuel the various physiological functions and activities. In effect, during intense physical exercise glucose and glycogen store are utilised to produce energy and sustain muscle activity, especial during events, such as a marathon, distance swimming or running. If the carbohydrates stores are depleted, physical performance, especially during endurance events, declines as a result.
Although there are many theories and approaches to nutrition, however, there is evidence suggesting that a healthy diet should provide an appropriate amount of carbohydrates, as well as proteins, fat, vitamins, minerals, dietary fibre and water, which are all important to sustain the various physiological processes, and enhance health, wellbeing a physical performance.