To diet well, know your carbohydrates

January 18, 2000

In dieting circles, a lot of time is spent discussing which is best, a high-carbohydrate or a low-carbohydrate diet.

What often gets lost is the overriding effect of total calories and the value of different types of carbohydrates: simple vs. complex; refined vs. unrefined. What do these descriptors for carbohydrates really mean, and why are they important?

cont. from lifestyle

Simple carbohydrates refer to single sugar molecules or pairs of sugar molecules bonded together. These single sugars are the basic building blocks of all carbohydrates.

Naturally-occurring single sugars are either glucose, fructose or galactose. They are called monosaccharides (mono for "one," saccharide for "sugar"). Disaccharides are two single sugars bonded together. The most famous is table sugar (sucrose), which is comprised of pairs of glucose and fructose. Another common disaccharide is lactose, the sugar found in milk. It consists of glucose plus galactose. Simple carbohydrates typically are found in the sugary foods and beverages at the top of the pyramid - sweets to be indulged in only occasionally.


Complex carbohydrates are comprised of long strands of sugar molecules linked together. Called "polysaccharides," foods high in complex carbohydrates don't taste much like sugar at all. While simple carbohydrates digest rapidly to form glucose, complex carbohydrates take longer to break down to glucose.

Glucose is the only sugar that can circulate in the blood; it provides the body with its all-important fuel. Breads, pastas, grain-based foods and starchy vegetables such as potatoes and corn are excellent sources of complex carbohydrates.

Refined carbohydrates

Refined carbohydrates have had certain coarse components of the plant removed. This results in food that is less susceptible to degradation by light and oxygen and often more appropriate for certain uses. Both simple and complex carbohydrates can be refined. For example, common table sugar, a simple carbohydrate, is refined from raw sugar. White flour, a complex carbohydrate, is refined from whole-wheat grain. Refining grains removes the germ and bran, which are storehouses of important vitamins, oils and fiber. In the United States, refined flours and products made from them are enriched, a process that adds certain nutrients back to the final product. Other examples of refined carbohydrates include fruit juices that have had the fiber removed.

Unrefined carbohydrates include breads and pastas made from unrefined grains. Examples include breakfast cereals like oatmeal, muesli and kashi; legumes and fruits and vegetables that have not had fiber or nutrients removed. "Whole grain" is another term for grains that have not been refined. Whole-wheat bread, like white bread, is a complex carbohydrate. Unlike white bread, it is richer in fiber and certain vitamins because it is unrefined.

While most research points to a diet high in carbohydrates, experts go on to say that the majority of those choices should come from complex and unrefined carbohydrates. Why?

We know that the germ and fiber are important for a number of reasons.

The germ of the seed is where essential vitamins and nutritious oils are concentrated. Fiber supplies indigestible "roughage," studied for its ability to bring down cholesterol levels and protect against certain types of cancer.

In general, the higher the fiber content and more complex the structure of a carbohydrate, the slower the rate of conversion from carbohydrate to blood glucose, a function important in maintaining consistent blood-sugar levels.

Today the grocery stores offer many choices. While it is easy to overload on simple and refined carbohydrates, it's also easy to enjoy the benefits of minimally processed complex carbohydrates by making wise food choices.

Maryland Cooperative Extension programs are open to all citizens without regard to race, color, sex, disability, age, religion or national origin.

Lynn F. Little is a family and consumer sciences extension educator for Maryland Cooperative Extension, Washington County.

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