Complex Carbohydrates

BIOCHEMISTRY 3(2+1)
Lesson 7 : Carbohydrates - Classification- Structure, Function

Complex Carbohydrates

Complex carbohydrates are chains of three or more single sugar molecules linked together. Long chains of sugar molecules are called starches and they serve as the storage form of energy in plants. Branched complex carbohydrates called cellulose form the structural components that give plants their shape.

Starches are fairly easy to digest. However, your body doesn't digest cellulose, which is an important component of dietary fibre.

Complex carbohydrates are found in fruits, vegetables, nuts, seeds and grains. Some examples of foods high in starchy complex carbohydrates include bread, cereal, rice, pasta, potatoes, dry beans, carrots and corn. Green vegetables like green beans, broccoli and spinach contain less starch and more fiber. All grains include starchy carbohydrates. However, whole grains -- such as whole wheat pasta -- are better because they also have more fiber.

Complex carbohydrates should be a major part of our diet; about half of your daily calories should come from carbohydrates -- mostly from grains, cereals, fruits and vegetables. Only a few of your daily calories should come from simple carbohydrates like table sugar.

Simple carbohydrates are made up of one or two sugar molecules linked together. Examples of simple carbohydrates include glucose, fructose (fruit sugar), sucrose (table sugar) and galactose (the sugar found in milk). Simple sugars are used as ingredients in candy, ice cream, cookies and other sweets. In addition, they occur naturally in fruits and to a lesser of extent in vegetables.

The glycemic index and glycemic load concepts have been developed to characterize food behavior during human digestion. They rank carbohydrate-rich foods based on the rapidity of their effect on blood glucose levels.

Glycemic index is a measure of how quickly food glucose is absorbed, while glycemic load is a measure of the total absorbable glucose in foods.

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Last modified: Wednesday, 18 January 2012, 6:36 AM