Some people use the terms carbohydrates and sugars interchangeably. However, this is not always the case. Sugars are a type of carbohydrates that impart sweetness to foods, but not all carbohydrates are sugars. Sucrose is a type of sugar known as a disaccharide. While not technically a simple sugar, sucrose is made up of two simple sugars, fructose and glucose.
Carbohydrate Types
Carbohydrates are one of the three main forms of calories. Carbs, as they are also known, serve as a source of energy for your body. Carbohydrates are present in most foods. However, grains, legumes, fruits and vegetables contain more carbohydrates than meats and cheeses. Carbohydrates come in two forms. Sugars are small molecules. They are distinguished from larger carbohydrates by their sweet taste. By contrast, large carbohydrates are not sweet-tasting. One example is starch, the main carbohydrate in foods including potatoes and rice.
Sugars
Sugars come in two varieties. Monosaccharides are single molecules known as simple sugars. The three main monosaccharides are glucose, fructose and galactose. Disaccharides, on the other hand, are made of monosaccharide pairs. Lactose, or milk sugar, consists of glucose attached to galactose. Sucrose, also known as table sugar, consists of equal parts glucose and fructose.
Sucrose in Foods
Monosaccharides and disaccharides lend a natural sweetness to foods. Most foods that are sweet contain a mixture of free fructose and free glucose, in addition to sucrose. Fruits and natural sweeteners such as honey and maple syrup are common sources of these sugars. Many vegetables contain them as well. Whether simple sugars or disaccharides predominate depends on the food. Honey, for example, contains mostly free fructose and free glucose. Table sugar, on the other hand, is made up entirely of sucrose.
Digesting Sucrose
The simple sugars, fructose, glucose and galactose, are essentially predigested. When you eat foods containing free sugars, they can be absorbed directly into your bloodstream without relying on the work of digestive enzymes. Sucrose, on the other hand, cannot used until broken down by the enzyme sucrase. This enzyme is present in your small intestine. Once digested, sucrose can travel in your blood as fructose and glucose to wherever it is needed.
References
- "Biochemistry"; Pamela C. Champe; 2005
- "Physiology"; Linda S. Costanzo; 2009
- "The Nutrition Doctor's A-To-Z Food Counter"; Dr. Ed Blonz; 1999
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