Nutrients provide your body with the energy it needs to maintain necessary processes such as growth, metabolism, brain function and digestion. The three major nutrients, also called macronutrients, are carbohydrates, protein and fat. To fuel necessary processes in your body, you must consume these nutrients regularly in your diet. Carbohydrates, specifically, are the body's main source of energy and are vitally important to the efficient functioning of many systems and tissues in the body.
Structure
At their simplest, carbohydrates are long strands of sugar molecules linked together. Some strands contain only a few molecules while others include thousands. According to the Harvard School of Public Health, the digestive system breaks all carbohydrates down into their individual sugar components because the molecules must be small enough to cross over into the bloodstream. Small sugar chains are referred to as simple carbohydrates because they can be easily digested and quickly broken down into individual sugar molecules. More complex carbohydrate chains take longer to digest.
Function
Carbohydrates are the body's main source of usable energy. The McKinley Health Center at the University of Illinois explains that every tissue and cell in the body uses glucose, a form of sugar, for energy. This energy can be used immediately, once the carbohydrate is digested and glucose sugars are sent into the bloodstream, or it can be stored within muscles and the liver for future use. Besides being the main source of energy, carbohydrates also function to regulate the digestive system and maintain intestinal health.
Requirements
According to the USDA Dietary Guidelines, 45 percent to 65 percent of your daily calories should come from carbohydrates. Grains, potatoes, pasta, fruits, vegetables, beans, soda, candy and other desserts are all considered carbohydrates. Ideally, however, the majority of your carbohydrate sources should be complex carbohydrates that take longer to digest. The Harvard School of Public Health lists examples of these as whole grain cereals for breakfast, whole grain breads for lunch or snacks, brown rice instead of potatoes or white rice, whole wheat pasta in place of regular pasta, plus any type of beans.
Fiber
Although most carbohydrates are categorized as sugars, fiber is also a type of carbohydrate. Fiber is naturally present in plant food sources such as whole grains, fruits, vegetables and beans. Because of its unique structure, fiber cannot be digested by the body. Instead, as the McKinley Health Center points out, this type of carbohydrate helps to eliminate bodily waste and maintains intestinal health as it passes through the intestinal tract.
Considerations
Whole grains provide the richest source of complex carbohydrates. According to the Feinberg School of Medicine at Northwestern University, foods such as brown rice, oatmeal, wheat bread and barley provide energy while also supplying fiber, vitamins, minerals and other biologically active compounds. The McKinley Health Center notes that diets particularly low in fiber can cause constipation and hemorrhoids and increase the risk for certain cancers. Alternately, diets rich in whole grains, rather than refined grains and simple sugars, have been shown to lower cholesterol and reduce the risk for obesity and chronic diseases such as heart disease, type 2 diabetes and high blood pressure.
References
- Harvard School of Public Health: Good Carbs Guide the Way
- McKinley Health Center at University of Illinois: Macronutrients--Importance of Carbohydrates, Protein and Fat
- USDA Center for Nutrition Policy and Promotion: Dietary Guidelines Report--Part D, Section 5
- Feinberg School of Medicine at Northwestern University: Carbohydrate Fact Sheet
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