Carbohydrates are compounds made up of carbon, hydrogen and oxygen. They are one of the three central components of the human diet, along with fat and protein. Enzymes in your digestive system break carbohydrates down into blood sugar, or glucose, which provides energy for your body. The three major types of carbohydrates are defined by their chemical structure and what happens to them after you eat them.
Simple Carbohydrates
Sugars are the basic "building blocks" of carbohydrates, and the more of these blocks there are in a carbohydrate, the longer it takes your body to digest it. Carbohydrates with only one or two of these building blocks are known as simple carbohydrates or simple sugars. Easily digested, simple carbohydrates enter the bloodstream almost immediately, which accounts for the "sugar rush" you get from a candy bar or sports drink. Single sugars include fructose--the sweetener in corn syrup--and galactose. Double sugars include lactose, found in dairy products; maltose; and sucrose, which is table sugar.
You'll find simple carbs in fruits, vegetables and dairy products. Refined and processed simple sugars are the ones you hear referred to as "empty calories," although they have the same number of calories per gram--about four--as more complex carbohydrates. They are considered "empty" because the nutrients and vitamins from the source product have been stripped away in processing, leaving only the sugar.
Complex Carbohydrates
Carbohydrates with more than two sugar building blocks are called complex carbohydrates--commonly referred to as starches. It takes your body longer to digest the sugars in complex carbs because those sugars are held together with chemical bonds that must be broken by enzymes. Your digestive system breaks off the sugars one by one and absorbs them into the bloodstream, so digestion occurs more slowly, and the energy boost is longer-lasting, than with simple carbohydrates. When runners "carbo-load" before a marathon, they're stocking up on complex carbohydrates to provide the slower-burning fuel they'll need.
Good sources of complex carbohydrates include whole grain breads, cereals and pastas; beans; and starchy vegetables such as potatoes, yams, corn and carrots. The National Institutes of Health recommend that most carbohydrates in your diet come from complex carbs and natural sugars, rather than processed and refined sugars.
Fiber
The chemical bonds in some carbohydrates can't be broken by the enzymes in your stomach and intestines. These indigestible substances simply pass through the body. This is "fiber," and it is critical to a healthy digestive system. Fiber can be soluble or insoluble. Soluble fiber absorbs water, forming a jelly-like mass that slows digestion, lowers cholesterol and makes stools easier to pass. Insoluble fiber helps move food and waste through the digestive tract, bulks up the stool and helps control the acidity in the colon, which can lower cancer risk.
Whereas sugars and starches come from inside the cells of plants, fiber is the remains of the cell walls themselves. Fresh vegetables, beans and peas, and whole grains are excellent sources of fiber.
Member Comments