What Makes Up Carbohydrates?

Carbohydrate is found in a wide variety of foods, from breakfast cereals, oatmeal, bread, rice, pasta, flour, baked goods, crackers, granola bar to fruits, fruit juice, legumes, milk, yogurt, sugar, candies and desserts. On food labels, it is possible to determine the amount of total carbohydrates per serving, but this macronutrient actually represent the sum of the starches, sugars and fiber.

Starch and Sugar

Starch is sometimes listed below the amount of total carbohydrates on a food label, while the amount of sugar is mandatory. Both starch and sugar contributes to supplying energy to the body's cells. Starches used to be called complex carbohydrates because of their chemical structure which comprises a minimum of three sugar molecules, while sugars were called simple carbs because they are formed by one or two sugar molecules. However, this classification is not used anymore because independently of the length of the starch or sugar molecule, these types of carbohydrates are both quickly converted to sugar after being digested.

Fiber

Fiber is also part of the total carbohydrate, but unlike starches and sugars, fiber is not digested, does not contribute to providing energy and are not converted to sugar. Fiber can be divided into two categories: soluble and insoluble. Soluble fiber absorbs water and forms a gel which slows down the digestion, helping to regulate blood sugar levels and lower blood cholesterol levels. This type of fiber is mostly found in psyllium, oat, flax seeds, okra, eggplant, oranges, apples, nuts and legumes. As for insoluble fiber, its main role is to give bulk to the stools and it can be found in whole grains, wheat bran and the peels of fruits and vegetables.

Available Carbohydrate

Total carbohydrate corresponds to the total amount of starch, sugar and fiber in a serving of foods. However, only the sugar and starch portion contributes to elevating blood sugar levels and provides calories. Fiber passes through the digestive tract without being absorbed. For this reason, people tracking their carbohydrate intake are recommended to track their available carbohydrate intake, also called net carb intake. Available carbohydrates give a more accurate picture of how carbohydrate-containing foods can influence your blood sugar levels and body weight. You can obtain the available carbohydrate content of a food by subtracting fiber from total carbs.

Recommendations

The Dietary Guidelines for Americans last published in 2010 indicate that carbohydrates should represent 45 percent to 65 percent of the calories. On the other hand, the Institute of Medicine in the 2005 "Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids" claims that carbohydrates are actually not required by the body if the diet provides fat and protein in sufficient amounts. Data is conflicting over what is the optimal amount of carbohydrate to consume, but studies have shown that humans can be healthy consuming diets with different amounts of carbohydrate, as long as other nutrient requirements are met.