Carbohydrates are defined as polyhydroxy aldehydes and ketones and their derivatives and vary from simple three-carbon sugars to complex polymers. Most carbohydrates conform tot the general formula (CH2O)n, but the classification of carbohydrates includes compounds that are not true hydrates as the names implies.
For example, deoxyribose contains 5 carbon atoms, 10 hydrogens, but only 4 oxygen rather than 5 as is customary for pentose. Moreover, some compounds that are properly classified as carbohydrates in terms of chemical properties contain nitrogen or sulfur addition to carbon, hydrogen, and oxygen.
Carbohydrates are classified into three main groups, monosaccharide, or simple sugars; oligosaccharides, of which the most prevalent in nature are the disaccharides; and polysaccharides the most complex of the carbohydrates.
Starch is by far the most important source of carbohydrates in the human diet amounting to approximately 50% of total carbohydrate in the United States, but often as much as 75% total carbohydrates in some of the developing countries.
Sucrose ranks next in important comprising about 25% of carbohydrates intake. In the last 70 years the intake of complex carbohydrates in the diet of United States has decreased, and the intake of sucrose has markedly increased.
Carbohydrates
