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Carbohydrates

Carbohydrates are one of the most important classes of biomolecules in nature and thus in our food. The name carbohydrate means hydrates of carbon and refers to the chemical structure which is (C·H₂O)_n, (to each carbon atom one water molecule is bound). Carbohydrates are also known as saccharides, which is derived from the Greek σάκχαρον (sugar), or in common language, sugars. Sugar in daily practice means sucrose, and the word sugars is generally only used for short-chain sweet carbohydrates. Chemically, however, sugars and carbohydrates are synonyms.

Carbohydrates have many functions in plants and animals. The plant cell wall consists of carbohydrates (such as cellulose and pectin), plants store energy as carbohydrates (starch), carbohydrates attract insects (sugar, honey) and have numerous other functions in plants. In animals and humans carbohydrates are the main energy source and many metabolic pathways are dependent on carbohydrates. Glycogen in muscles and the liver is an energy source for the body, other carbohydrates are important in blood clotting, in the immune system and in many other functions of the body. Other important roles of carbohydrates in nature are the chitin skeletons of insects and one of the building blocks of all DNA is deoxyribose, a modified carbohydrate.

Carbohydrates can be divided in monosaccharides, oligosaccharides and polysaccharides. A monosaccharide is a simple small molecule, such as glucose (dextrose) or fructose. Only a limited number of monosaccharides exist in nature. Monosaccharides can easily form smaller (oligosaccharides) or larger (polysaccharides) chains, thus creating an enormous number of possible combinations.

The rules of chemical nomenclature prescribes the ending -ose for carbohydrates, such as glucose, fructose, lactose etc. However, many of the polysaccharides still have old names with a different ending, such as amylopectin and inulin.

In the following sections different aspects of carbohydrates are further described.

• Carbohydrate chemistry
• Carbohydrates
  • Monosaccharides
    • Glucose
    • Fructose
  • Disaccharides
    • Lactose
    • Maltose
    • Sucrose
  • Trisaccharides
  • Oligosaccharides
    • Polysaccharides
    • Fructans
    • Pectin
    • Starch
  • Polyols
• Carbohydrate metabolism
• Carbohydrate intolerances
  • Fructose intolerance
  • Lactose intolerance