"With some experts claiming people should follow a diet low in carbohydrates, and other experts recommending people follow a diet of high carbohydrates, whom do you believe?"

by Charles C. Gilmore, PhD (clinical nutrition), and Thaya E. Gilmore, PhD (clinical nutrition)

Carbohydrate, a vital energy source, is the most widely consumed substance in human nutrition. The simplest carbohydrate, glucose, provides essential fuel for the brain. With some experts claiming people should follow a diet low in carbohydrates, and other experts recommending people follow a diet of high carbohydrates, whom do you believe?

In most of the world, high-starch cereal grains provide most of the energy necessary in the diet, compared to our culture, in which starchy foods and sugar are regarded as undesirable or unnecessary dietary components. In fact, over 50 percent of the "energy requirement of people throughout the world is met by consumption of starches and sugars stored in the leaves, stems, fruits, seeds, and roots of plants. The ability of plants to harness solar energy in the form of usable carbohydrates is basic to the continuance of life by all species."

Composition of Carbohydrates

Carbohydrates contain carbon, hydrogen and oxygen. They are simple sugars or polymers (a natural substance, usually of a linked sequence of identical chemical units) of sugars, such as starch, that can be hydrolyzed to simple sugars by the action of digestive enzymes. The simplest form of carbohydrate is called a monosaccharide (mono = one; saccharide = sweet). Glucose, the building block of starch, is a monosaccharide that occurs in food and is the most common source of fuel for the cells. The carbohydrate becomes less sweet as the number of monosaccharides in the chain increase. For instance, maltodextrins are oligosacchrides (oligo = few) and are not as sweet. When two monosaccharides join together, they result in a disaccharide (di = two). Sucrose (table sugar) is a disaccharide. Lactose is the sugar in milk. Starches are polysaccharides (poly = many), which are long chains or sugar molecules joined together. Starches do not taste sweet.

Sources of Carbohydrates

Carbohydrates are derived from plants. In fact, almost all of the starches and sugars we need to burn for energy come from plants, which use photosynthesis to synthesize the carbohydrate. The plant uses some of the carbohydrate to meet its own metabolic needs, such as amino acids that make up its proteins. Carbohydrates are classified according to their chemical structure and are divided into two groups: simple carbohydrates and complex carbohydrates. Some foods contain a large amount of carbohydrates, such as potatoes, cereals, and legumes, while other foods have a small amount of carbohydrate, such as broccoli, salad greens, or string beans.

Simple Carbohydrates

Simple carbohydrates or sugars form crystals and can be dissolved in water; they are easily digested. Natural sugars are found in fruits and some vegetables, honey, and maple sap.

Complex Carbohydrates

Complex carbohydrates are composed of complex chains of sugars, usually identified as starches and fibers. The human body can break down and digest starches, but the human bodyÍs digestive system lacks the enzymes needed to break down fiber.

The Glycemic Index

When carbohydrates are discussed, the word is virtually synonymous with glycemic index. The glycemic index is a ranking of foods based on their effect on blood sugar levels. For instance, carbohydrate foods that break down quickly during digestion have the highest glycemic index values, because their blood sugar response is fast and high. The substance that produces the greatest rise in blood sugar levels is pure glucose; on the other hand, carbohydrate foods that break down slowly release glucose gradually into the bloodstream have low glycemic index values.

Another factor that influences the glycemic index is cooking and processing of food, because it increases the amount of starch in the food. There are two types of starch in foods: amylase and amylopectin. The more amylase starch a food contains, the lower the glycemic index. Amylase foods are legumes and rice. Amylopectin is broken down more easily, causing faster digestion and giving the food a higher glycemic index.

Low Glycemic Index Eating

Overall, eat whole grains and legumes (dried beans and peas, barley, oats) in combination with fruits, vegetables, certain breads (whole grain, sourdough, pumpernickel), corn tortillas, pasta, and rice to maintain low glycemic index eating. Eat most vegetables, as they are low in carbohydrates, plus they provide valuable amounts of fiber, vitamins and minerals. Avocados and nuts contain little carbohydrates, and their glycemic index is zero.

Sugar

The type and amount of sugar also will influence a foodÍs glycemic index. Fruits with fructose (apples and oranges) have a low glycemic index. Our bodies metabolize fructose in such a way that results in a slow release of glucose, lowering the glycemic index of a food.

Insulin

In talking about carbohydrates, the topic of insulin also needs to be addressed. One of the jobs of the pancreas is to produce the hormone insulin. Carbohydrate stimulates the secretion of insulin more than any other component of food. It makes sense that the slow absorption of the carbohydrate in our food means that the pancreas doesnÍt have to work as hard; therefore, it needs to produce less insulin. On the other hand, if the pancreas is overstimulated or becomes exhausted over a long period of time, it may become susceptible to develop diabetes. Insulin also influences the way food is metabolized; it helps determine whether fat is burned or if carbohydrates can meet the bodyÍs energy needs, and determines whether fat is stored in the body.

Cautions

While most people can utilize carbohydrates in their diet, some people who cannot, such as those with diseases such as diabetes (need a balance of protein, fat and high-fiber starchy foods to regulate the glucose), heart disease (need high-fiber, complex-carbohydrate diet), cancer (need increased carbohydrates) or celiac disease (need to avoid gluten).

Recommendations

Carbohydrates can be enhanced by using supplements such as greens. Greens provide concentrated chlorophyll, antioxidants, vitamins, and enzymes that clean the body and boost the immune system. Eat carbohydrates drawn from vegetables, fruits, and grains. Dried beans and peas provide the best food values. Read labels. Watch intake of processed sugars and refined carbohydrates. Build a diet around raw or slightly cooked vegetables and lightly, naturally processed grains.