Carbohydrates are composed of three elements: carbon, hydrogen and oxygen. The word carbohydrate was originally derived from the fact that the greater part of the compound in this class had the empirical formula Cn(H2O)n. The values of n range from three to many thousands. The number and arrangement of these elements in the carbohydrate molecule differentiate one carbohydrate from another.
This formula now considered too restrictive and a more useful definition might be ‘polyhydroxy aldehydes or ketones and their derivatives’. This later definitions encompass deoxy sugars, sugar alcohols, sugar acids, amino sugars.
Plants are the primary sources of carbohydrates in the human diet. Carbohydrates occur in fruits and vegetables as storage reserves in seeds, roots, and tubers; in the sap; and as constituents of the structural tissues, they are also found in the milk, blood, and tissues of animals.
Carbohydrate should make up about 5/7 of the solid part of the diet and ideally no more than 2/7 of the carbohydrates should be refined sugars such as glucose.
Carbohydrate definition and food sources
