Dr. Lee, the Healthy Professor

Carbohydrates - Friend or Foe?

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Carbohydrates is the name given to one of the three macro nutrients. Fats and proteins are the other two. Carbohydrates are derived primarily from plants (milk sugar lactose is the exception) and best known for their contribution to available quick energy.

Sugars, starches and fiber are the three types of carbohydrates we eat. Sugars in the form of honey, syrups and refined products are well known sources of energy and taste in our food chain. Starches come primarily from root vegetables, cereal grains, corn, and rice. Fibers are the non-digestible forms which comes from fruits, vegetables and grains. Fibers do not contribute to the calorie count but do make a major contribution to maintaining a clean and healthy intestinal system. Most of the carbohydrate sources, fruits, vegetables and grains also carry significant nutrients necessary for optimum health.

So how much do we need? There is a wide divergence of opinion on this. Government agencies and Dietitian Associations recommend 55 to 65 per cent of our calories come from carbohydrates. "High protein" diet advocates push for the minimal number of carbohydrate calories. I am an advocate of the 40 - 30 - 30 eating plan, where only 40 per cent of calories come from carbohydrates. The remaining calories are equally divided between protein and "good" fat. The modern trend as evidenced by the Canada Food Guide recommends 6 - 12 servings of grain products and 5 - 9 servings of vegetables and fruit but only 4 - 6 servings of protein rich foods.

Many people increase the intake of whole grain products in the form of muffins, breads, cereals, and bagels to increase their fiber intake. However, the average serving of vegetables and many fruits, particularly apples and berries, contain 30 to 60 per cent more fiber than the average serving of grain products. I find it interesting that a 1998 book published by the American Dietetic Association lists the functions of sugars (the end product of carbohydrate digestion) as contributing to taste, aroma, texture, color and body of foods. "All of which add to our enjoyment". Sugar is also listed as a food preservative. There is no mention of "nutritional value", mainly because there is very little value other than as a source of easily obtained energy. The Inuit population survived for centuries without eating carbohydrates and there is no RDI (Recommended Daily Intake) for carbohydrates.

It is increasingly recognized that chronically elevated levels of insulin in the blood are responsible for increased fat storage and may be implicated in creating insulin resistance which is a precursor to Type II Diabetes. Statistics from the World Health Organization show us that obesity is doubling every 5 years and we now find a new Type II Diabetic every 8.5 minutes in this country and that is a 3 fold increase over the last 5 years. Many blame these two epidemics on chronically elevated insulin levels which occur from living and eating in "Carbohydrate Hell".

Not all carbohydrates are created equal. The refined and the starchy carbohydrates are digested into sugars and absorbed much faster than their higher fiber, less processed, more complex cousins. The measure is known as the Glycemic Index (GI) which reflects the relative rate of blood sugar elevation. This in turn affects the levels of insulin in the blood. Sugar has a GI of 100 and the GI of white bread is 97, which means 97 per cent of sugar. On the other hand nuts have a GI of 15, which means the rate of sugar rise is only 15 per cent. Obviously to control insulin one should choose low GI high fiber foods like apples at 59 and broccoli at 23, instead of high GI, low fiber bananas at 82 and raisins at 91.

Carbohydrates are valuable sources of energy and other nutrients. But they need to be consumed in combination with proteins and fats to control the rate of blood sugar rise, which controls insulin. This will help to control hypoglycemia, weight gain and the development of insulin resistance.

Try to become familiar with the GI of the foods you eat.


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