More commonly known as simple carbohydrates, monosaccharides and disaccharides play an important role in your body's energy metabolism. Constructed of single units of sugar, the monosaccharides glucose, fructose and galactose are among the most common simple sugars. Made of two monosaccharide units linked together via chemical bond, sucrose, lactose and maltose are the most important disaccharides in our diet.
Glucose
Also referred to as blood sugar or dextrose, glucose is found naturally in some foods or in your body after digestion of complex carbohydrates. Glycogen, your body's main energy source for fueling physical activity, is made up of chemically interlinked glucose molecules. According to Sareen S. Gropper, Ph.D., author of "Advanced Nutrition and Human Metabolism", a blood sugar level greater than 100 milligrams per deciliter in a fasted state may indicate the onset of type 2 diabetes.
Fructose and Sucrose
Fructose, sometimes called levulose or fruit sugar, is found in a wide variety of fruits, honey, food condiments, sodas and juices. Considered the sweetest of the simple carbohydrates, fructose gets absorbed directly into your bloodstream during digestion and eventually converts to glucose in the liver. Frances Sizer, R.D., author of "Nutrition: Concepts and Controversies", mentions fructose is the most significant source of sugar in the diet of Americans. This common monosaccharide combines with glucose to form sucrose in foods such as beets and maple syrup.
Galactose and Lactose
The monosaccharide galactose occurs naturally in milk, combining with glucose to form lactose, or milk sugar. When milk is consumed, the digested galactose is converted to glucose for use in energy metabolism. Considered the least sweet simple sugar, lactose is broken down by an enzyme called lactate dehydrogenase. Approximately 25 percent of Americans lack this enzyme needed to digest lactose and experience cramping and bloating with consumption of milk-based products, says author-dietician Sizer.
Maltose
Two glucose molecules linked together form the disaccharide maltose. Commonly found in cereals, beer and malt beverages, maltose is easily broken down into glucose during digestion. Maltose forms during the fermentation of grains, fruits and vegetables as a result of the decomposition of starch. Also known as malt sugar, Kenneth Saladin, Ph.D., author of "Anatomy and Physiology: The Unity of Form and Function", mentions this form of simple carbohydrate makes the smallest contribution to the carbohydrate portion of the American diet.
References
- "Advanced Nutrition and Human Metabolism"; Sareen S. Gropper, Ph.D.; 2008
- "Nutrition: Concepts and Controversies"; Frances Sizer, R.D.; 2007
- "Anatomy and Physiology"; Kenneth Saladin, Ph.D.; 2009
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