- Simple Carbohydrates – containing no more than two molecules; often referred to as sugars.
- Monosaccharides – consist of a single sugar molecule (mono means one and saccharide means sugar); the three most common being glucose, fructose and galactose
- Disaccharides – consists of two joined sugar molecules (di means two); the three most common disaccharides are lactose, sucrose and maltose.
- Lactose is composed of glucose + galactose
- Sucrose is composed of glucose + fructose
- Maltose is composed of glucose + glucose
- Complex Carbohydrates – are polysaccharides (poly meaning many), meaning they contain long chains of glucose molecules. Types of complex carbohydrates include glycogen, starches, and some fibers (for more information about fiber please refer to the article “Fiber 101”).
- Starch – storage form of carbohydrates found in plants
- Glycogen – storage form of carbohydrates found in humans and animals
Sources of complex carbohydrates include grains such as wheat, oats, barley, rice, and corn; tubers (potatoes and yams); and the legume family with beans, legumes and peas.
Why is it important? Simply stated, glucose is the form of sugar that the human body uses for energy, therefore all forms of carbohydrates must be broken down and converted to glucose. Glucose travels through the blood stream to provide energy to cells. If there is not a demand for glucose it can be stored in muscles and the liver, in the form of glycogen. Therefore, when the body does need this stored glucose, such as during intense exercise or training, the glycogen is available to provide this needed energy.
Not only are carbohydrates used to fuel exercise, they also are needed to fuel daily activities. Fat and protein can also be used for energy by most of our cells, except for the brain. If carbohydrate intake is inadequate the body will break down stored fat into an alternative fuel know as ketones, a process called ketosis. Elevated ketones in the blood cause the blood to become acidic, a dangerous condition called ketoacidosis.
In addition, with an inadequate intake of carbohydrates, the body can make its own glucose from protein. Gluconeogenesis is the process in which proteins are broken down into amino acids and then converted into glucose. The drawback is that if amino acids are being used to produce glucose, they cannot fulfill their role of making cells, repairing tissues, etc.
How much do you need? The Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates is 45-65% of total daily calorie intake 1. The Dietary Guidelines for Americans recommend that the carbohydrates consumed should be primarily fiber-rich whole grains, fruits and vegetables. Likewise, foods should be consumed and prepared with little to no sugars and/or caloric sweeteners2.
Information from Evolution Nutrition
Lauren Rezende MPH, RD
- National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.
Dietary Reference Intakes for carbohydrate, fiber, fat, fatty acids and protein. 2005; cited 2010 September 6. Available from: http://www.iom.edu/Global/News%20Announcements/~/media/C5CD2DD7840544979A549EC47E56A02B.ashx.
- US Department of Health and Human Services (USDHHS) and US Department of Agriculture (USDA). Dietary Guidelines for Americans. 2005; cited 2010 September 6. Available from: http://www.health.gov/dietaryguidelines/