Carbohydrates are composed of only three elements – carbon, hydrogen and oxygen. When they are broken down, they produce large amounts of energy. Without this energy, legs could not walk, the brain could not create and calculate, lungs could not inhale and exhale and the heart could not beat. Carbohydrates produce 4 calories for every gram.

A Clean-Burning Fuel
Carbohydrates are an abundant, easily obtained and clean burning fuel source, and therefore our primary fuel. There are three basic types:

• monosaccharides
• disaccharides
• polysaccharides.

Monosaccharides, like most families, have certain characteristics in common. They consist of only one single sugar. They are crystalline, dissolve easily in water, taste sweet, and are absorbed directly into the bloodstream from the digestive tract. Glucose and fructose are examples of single sugars that our digestive system can absorb. Ribose and deoxyribose are monosaccharides that are essential components of our genetic molecules Ribonucleic Acid (RNA) and Deoxyribonucleic Acid (DNA). Glucose is the sugar required in greatest quantity by the body, and most of that is used by the brain. Glucose can be utilized in three different ways:

• It can be “burned” for energy.
• It can be stored in small quantities as glycogen in muscle and liver cells.
• It can be changed to fat and stored in fatty tissues to serve as an energy bank.

While glucose may be the most important monosaccharide, fructose – which is found in fruits and honey – tastes the sweetest. It is also absorbed much more slowly from the digestive tract than glucose. Galactose, or milk sugar, is produced in breast milk.

How Sweet It Is
The next branch on our carbohydrate family tree is the disaccharides, which are formed by joining two monosaccharides together.

Disaccharides, like their simpler cousins, are crystalline, easily dissolved in water, and sweet to the taste. However, these double sugars cannot be absorbed by the digestive tract. To be useful in our bodies, disaccharides must first be split by specific enzymes into their component monosaccharides.

When glucose and fructose are joined together, the disaccharide formed is sucrose, or common table sugar. Sucrose is found in large quantities in beets and sugar cane. Lactose, the sugar associated with milk products, is a disaccharide formed from glucose and galactose. The enzyme required to split lactose is called lactase. People who lack this enzyme are unable to digest dairy products.

Both monosaccharides and disaccharides are referred to as simple sugars. These sugars are found in a wide variety of refined foods, under an equally wide variety of names. Corn syrup, invert sugar, corn sugar, sorbitol, levulose, dextrose and fructose are all aliases for simple sugars.

The Complex Cousin
The last branch on our carbohydrate family tree is the polysaccharides, carbohydrates with three or more sugar molecules linked together. Most naturally occurring carbohydrates come in this form. When compared to their monosaccharide and disaccharide cousins, this family group exhibits very different characteristics.

Polysaccharides are powdery instead of crystalline, they are too large to dissolve in water, and they are not sweet to the taste! Cornstarch is an example.

Starch, glycogen and fibre are the most common polysaccharides. They are called complex carbohydrates because of their large, branching structures.

Starch is a plant polysaccharide made up of hundreds and even thousands of individual sugar molecules linked together in long branching chains much like an intricate Indian bead design. This type of carbohydrate is found in grains, beans, peas, potatoes, squash and other vegetables.

In order to be absorbed, each of the hundreds or thousands of single sugars making up the starch molecule must be broken off, one by one, by the proper enzymes. For this reason, starch provides a slow but steady supply of sugar to the blood.

Glycogen is a polysaccharide made by animals. When we consume more carbohydrate then we need for energy, the liver converts the excess to glycogen for storage. Glycogen is a very large molecule, and may contain up to 10,000 glucose sugars linked in long chains. Muscle cells also store glycogen.

Between the liver and muscle, approximately 425 g, not quite one pound, of glycogen is stored in the body. This is a relatively small energy bank, so it must be continually renewed through the food supply.

During exercise or when we skip a meal, glycogen is broken down to glucose to provide a source of quick energy.

Five kinds of plant polysaccharides fall under the label of fibre. They are cellulose, hemicellulose, lignins, pectins and gums.

Fibre is not a nutrient because we do not have the enzymes necessary to break it down and absorb it. However, it is an essential component of a good diet and provides many health benefits.

Cellulose, hemicellulose, and lignins are not soluble in water and are called insoluble fibre or roughage. Wheat bran that you use to make bran muffins contains this kind of fibre. Pectins and gums are water soluble fibre found in oats, flaxseed, apples and other foods. Together they aid the digestive system by moving stool through the large intestine more quickly and binding toxins, thereby limiting the time they can be in contact with the intestinal wall. Soluble fibres bind cholesterol in the gut, preventing it from being reabsorbed and making it easier to excrete in the stool. This action can actually lower blood cholesterol levels.

Carbohydrate Foods
Carbohydrates run our engine and we need a steady supply every day if we want to perform our best. Eating a variety of whole foods such as whole grain breads and cereals, pasta (whole grain), fresh fruits and vegetables, and peas and beans helps keep blood sugar levels steady and ensures an adequate supply of fibre.

Whole foods supply both the carbohydrates we need, and all the nutrients required to metabolize them. They protect us from “nutrient debt” caused by eating foods stripped of fibre, vitamins and minerals. Limiting the use of simple sugars and refined white flours can help prevent hypoglycemia. That means reducing intake of table sugar, many processed breakfast cereals, soft drinks, candies, cakes, cookies and white breads.