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Sugars are commonly thought of as the white, granular substance known as table sugar. However, there are many different types of sugars. As with all carbohydrates, sugars are made up of a combination of carbon, hydrogen and oxygen. Sugars can either belong to the category of foods known as simple carbohydrates or complex carbohydrates.

Simple carbohydrates are made up of either a single chemical unit (monosaccharide) or two units (disaccharide) of sugar. There are three types of monosaccharides:

• Glucose. Also known as dextrose, it has a mildly sweet flavor. Glucose is the main form of sugar that circulates in the bloodstream and is often referred to as "blood sugar."
  
  
• Fructose. The sweetest of the sugars, it occurs naturally in fruits and honey. It is also found in high-fructose corn syrup (in soft drinks) and is a major source of sugar in the diet of Americans.
  
  
• Galactose. Hardly tastes sweet, found in gums, dairy products and sugar beets.

When two monosaccharides join together, they become disaccharides. The following are the three disaccharides found in foods:

• Sucrose (glucose + fructose). Commonly called table sugar and also found naturally in sugarcane, sugar beets, honey and many fruits and vegetables.
  
  
• Lactose (glucose + galactose). Naturally occurs in milk and dairy products.
  
  
• Maltose (glucose + glucose). Also known as malt sugar, it is the least common disaccharide in nature.

Complex carbohydrates are sugars that are made up of longer chains of sugar units. However, they do not taste sweet because the size of their molecules is too large to fit on the sweet receptors of the taste buds. They are found in whole-grain breads and cereals, legumes and starchy vegetables that provide nutrition in the form of vitamins, minerals and fiber.

Complex carbohydrates are composed of at least three glucose units. In some cases, they may be composed of many monosaccharides strung together in compounds known as polysaccharides. When a person consumes a complex carbohydrate, it is broken down in the body into a simple sugar.

Sugars are also classified according to their source. Intrinsic or naturally occurring sugar refers to the sugar found naturally in foods such as fruits, vegetables and milk products. Extrinsic or added sugar refers to the sugar added while processing foods, such as the sugar added to soft drinks, fruit beverages, ice cream, snacks and other processed foods or beverages. Naturally occurring sugars are no healthier for a person than extrinsic sugars. All sugars provide energy for the body in the same way.

Refined sugar is a term that describes sugar separated either from the stalk of sugarcane or from the beet root of sugar beet. Juice in the plant that contains the sugar is extracted and processed into dried sugar crystals. It is then sold as granulated or white sugar. Sugarcane or sugar beet that has been processed into table sugar leaves behind thick syrup known as molasses. Brown sugar is refined sugar combined with molasses for color and flavor. Raw sugar (also called turbinado, demerara, or muscavado sugar) is derived from processed sugarcane that has undergone a specific refining process.