Generalities and distribution in nature ô Classification ô Carbohydrates in nutrition

Generalities and distribution in nature

Carbohydrates are energy-rich compounds composed of carbon, hydrogen and oxygen. They are the body’s main source of energy.  During digestion, most carbohydrates are changed to simple sugar glucose.  In fact, the word glucose derives from the Greek root “glucus” which means sweet.  Carbohydrates or “sugars “are widely diffused in nature and are especially found in the vegetable kingdom where they are formed, but also in supportive materials (cellulose) or in stored materials (starch). Carbohydrates are also found in animals in the form of glucose-glycogen either in a free form or in combination with proteins, carbohydrates, fats or with other compounds of biological interest.

From a chemical point of view they are compounds known as “ternary substances” formed by the union of C, H, O  although in the composition of some, other elements are present such as sulphur and nitrogen.

Carbohydrates are divided in two main types: complex which includes starch and cellulose and simple which are the sugars found in fruits, honey, milk, sugar cane and beets.  Cellulose is the fibre found in the cell walls of fruits, vegetables and grains.  Starches are made up of long chains of simple sugars. They are broken down into simple sugars and subsequently absorbed by the body.

Classification

Carbohydrates are classified in:

Carbohydrates in nutrition

Carbohydrates are pre-eminent in the human diet.  They are found in grains and cereals, legumes, fruit, milk, meat and fish.  They cover about half the requirements for energy (50-60%) and serve as a rapid energy source: 1g. of sugar supplies 4 calories.