Carbohydrates constitute one of three basic components of the foods you eat. Along with fats and proteins, carbohydrates furnish the raw materials for the innumerable metabolic processes that take place in your cells. All cellular activities require energy, and glucose is your body’s preferred source of fuel. Because they are more readily reduced to glucose, carbohydrates represent a more direct pathway to energy production than fats and proteins. Thus, the majority of calories in your diet should come from carbohydrates.
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Simple Versus Complex
Some carbohydrates are more readily digested, assimilated and metabolized than others. Those that require minimal enzymatic digestion before they pass through your intestinal wall and into your bloodstream are called simple carbohydrates. Monosaccharides, such as glucose, fructose and galactose, are the most quickly absorbed. Digestion of disaccharides, such as lactose and sucrose, is slower, and processing of complex carbohydrates – starches, hemicelluloses and fibers – is slower still. Some carbohydrates, such as cellulose, are indigestible.
Because they pass through your intestinal wall so easily and quickly, simple carbohydrates trigger a more rapid increase in your blood glucose levels. Such foods are said to have a high glycemic index. According to a March 2011 review in “Nutrition Journal,” the routine consumption of high-glycemic-index foods is associated with an increased risk for diabetes and heart disease. Conversely, consuming more complex carbohydrates – those with a low glycemic index – confers a protective effect. Because glucose is the prototype for the glycemic index, it is assigned a value of 100. Carbohydrates with a glycemic index below 55 to 60 are deemed to be “healthier” than foods with higher values.
According to the Mayo Clinic, carbohydrates should comprise 45 to 65 percent of your total caloric intake. The vast majority of these calories should come from complex carbohydrates, such as whole grains, vegetables and legumes. Fruits are a source of complex carbohydrates, but they also contain some simple carbohydrates, such as glucose and fructose. To limit Americans’ intake of simple carbohydrates, the American Heart Association recommends no more than 150 calories of “added sugar” – about 9 tsp. – for men each day, and no more than 100 calories for women. Added sugars are those used by food processors to make their products more palatable and those you add while cooking or dining. A single can of sweetened soda contains about 8 tsp. of added sugar.
Carbohydrates represent an essential part of your diet. While other macronutrients – fats and proteins – can be metabolized for energy, carbohydrates are more readily converted to glucose, your body’s preferred fuel source. Low-carbohydrate diets may offer some health benefits when compared to the typical American diet, which contains large amounts of simple carbohydrates and unhealthy levels of saturated and trans fats. However, “low-carb” diets are not “no-carb” diets, and scientists are still collecting data to determine the long-term health effects of low-carbohydrate meal plans. Ask your doctor about the best diet for you.