Carbohydrate is the term given to a group of macronutrients which contain carbon, hydrogen and oxygen combined in a unique way. Carbohydrates can be small or large molecules, depending on the number of structural units from which they are made. Carbohydrate is therefore not a single entity, but a group of substances with major chemical and nutritional differences. The classification of carbohydrates is not uniformly agreed upon, but the strict chemical classification breaks them into monosaccharides, disaccharides, oligosaccharides and polysaccharides, depending on the number of sugar units. However, for simplicity and practicality, it is still probably best to consider three major categories of interest: sugars, starches and fibre.
Sugar. Sugars, which are often called ‘simple sugars’, are made up of only one or two structural units. Monosaccharides (mono meaning one and saccharide meaning sugar) are made up of a single carbon ring. These include glucose, fructose and galactose. Glucose is the major monosaccharide in the body and is also known as dextrose or blood sugar, fructose is found in fruits and galactose is only present by itself in nature in very small amounts. Two monosaccharides joined together are called a disaccharide (di meaning two). These include maltose, sucrose and lactose. Maltose is present in sprouting grains and is made up of two glucose units bonded together. Sucrose, more commonly known as table sugar, consists of glucose and fructose. Lactose consists of glucose and galactose and is the sugar present in mammalian milk.
Starch. A carbohydrate containing many monosaccharide units is called a polysaccharide (poly meaning many) or starch. More commonly known as ‘complex carbohydrates’ these are the storage forms of carbohydrates in plants – amylase and amylopectin.
Fibre. Contrary to popular belief, fibre is not just one substance. Rather, the term is an all-embracing one for a number of components found in plants, which include cellulose and other insoluble fibre components and gel-forming or soluble fibres such as pectins, gums and mucilages found in fruits, oats and barley. All fibre is made up of multiple saccharide units and nutritional scientists now prefer to call fibre a non-starch polysaccharide (NSP).
*102\186\4*
