Appears in
Oxford Companion to Food

By Alan Davidson

Published 2014

  • About

Sugar is fundamental to the nutrition of plants and animals, and exists in one form or another in all living creatures. Sugars are carbohydrates, i.e. their molecules consist of carbon, hydrogen, and oxygen. (These molecules are relatively small. The more complex carbohydrates such as starch and cellulose are mainly composed of many sugar molecules joined together.) There are many different chemical forms of sugar.

The simplest sugars are termed monosaccharides, ‘single sugars’. Of these, the fundamental one is dextrose (commonly called glucose), which occurs naturally in fruits and vegetables, and also in the blood of animals, where it provides a short-term store of energy. The digestion of all carbohydrates is essentially a process of reducing them to dextrose. That is why powdered glucose and glucose syrup, which consist mainly of dextrose, give quick energy. They need no digestion, but go straight into the blood.