Definition of Sugars

Sugars are simple carbohydrates composed of carbon, hydrogen and oxygen in a ratio of two atoms of hydrogen and one atom of carbon for each atom of oxygen. Sugars can be defined by the number of saccharide molecules they contain, with monosaccharides and disaccharides combining to form the simple sugars. In its dietary form, sugar is an edible crystalline substance with a sweet taste. Sugar can come from a number of natural plant sources. Table sugar consists of sucrose, a disaccharide that is typically extracted from beets or sugar cane

Monosaccharides

Monosaccharides, which form the basic unit of all carbohydrates, contain just one saccharide molecule. Monosaccharides can be classified by the number of carbon atoms they contain. For example, trioses, tetroses and pentoses contain three, four and five carbon atoms, respectively. Common examples of monosaccharides include glucose, fructose and galactose. Glucose plays a particularly important role in the body. It provides energy for cells, is stored in the muscles and liver in the form of glycogen for later energy use, is converted to fat for energy and helps formulate amino acids.

Monosaccharide Sources

All fruits, vegetables, grains and dairy products naturally contain monosaccharides. Glucose is typically not found in foods in its singular form, although it combines with other monosaccharides to form the disaccharides in various food sources. Fructose is most commonly found in fruits and honey, and is the sweetest of the monosaccharide carbohydrates. Galactose is formed in the mammary glands of animals and helps form lactose, the natural sugar in milk.

Disaccharides

Disaccharides are sugars that consist of two saccharide molecules. All disaccharides contain glucose as a primary structural component. Three common dietary disaccharides include sucrose, lactose and maltose. Sucrose is formed from glucose and fructose, lactose consists of glucose and galactose and maltose is formed from two units of glucose.

Disaccharide Sources

Sucrose is the most prevalent dietary disaccharide, and exists in almost all foods that contain carbohydrates. In addition to beets and sugar cane, sucrose can be found in brown sugar, syrups and honey. Lactose is only found in milk and milk-based products, while maltose is a malt sugar that exists in beer, seeds and some cereal products.

Polysaccharides

Polysaccharides refer to carbohydrates formed from three or more saccharide molecules. Starch and fiber are both plant polysaccharides formed from hundreds of conjoined glucose molecules. High amounts of starch can be found in grains, peas, beans and potatoes, while fiber is most prevalent in whole-grain cereals, beans and fruit.