Carbohydrate is an important part of a healthy diet because it serves essentially as a fuel for the body. It can also serve as a good source of essential vitamins and minerals. Common carbohydrate sources include bread, rice, beans, potatoes, yam, garri, corn, etc.
There are three varieties of carbohydrates; sugars, fibres and starches. The basic building blocks of carbohydrate are sugar molecules. More complex forms of these molecules make up starch and fibre. Following a carbohydrate-rich meal, the digestive system tries to break down the complex molecules into simple sugars for easy absorption into the bloodstream. Fibre, though a carbohydrate, is an exception here. Because of the complex articulation of the glucose molecules, the enzymes in the digestive tract are unable to sufficiently break them down. They are passed out of the body undigested. Initial thoughts were that simple sugar meals where bad and complex sugars were good. Current scientific thinking has shown it is not as straightforward as that. This has thrown up a totally new understanding which uses the glycemic index as a determinant of what forms of carbohydrate are to be consumed generally moderately and sparingly stop
This measures the rate and measure of the rise of blood sugar after consuming a carbohydrate-rich meal. Some meals include a sharp rise in blood sugar and examples of these include potatoes, bananas, white bread, refined breakfast cereals, white rice, soft drinks, sugars, etc. Examples of meals with low glycemic index (they cause a gentle rise in blood sugar) includes legumes like beans, whole fruits, brown rice, whole grain cereals, etc. High glycemic index meals have been linked to diabetes mellitus and heart disease. The steep rise in blood sugar places a lot of burden on the pancreas to secrete insulin. This may eventually “burn out” the pancreas leading to diabetes mellitus. On the other hand, low glycaemic index meals have been shown to be useful in the control of Type II diabetes. The large secretion of insulin secreted after a meal with a high glycaemic index drives glucose into the tissues, and this encourages the deposition of fat which invariably causes weight gain. The rapid fall in the blood sugar after insulin secretion induces hunger and the resulting hypoglycaemia may cause a reduction in energy.
One important factor determining a food’s glycaemic index is the degree of processing it has undergone. A ready example is the processing of the flour used in producing bread. Today’s refining process produces fine, more delicate textured flour, but it also steals away the life of the grain. The bread most of us eat today provides calories but little food value. Someone referred to this as the “Great Grain Robbery.” Don’t mind the labels that say that the bread is enriched with vitamins and iron. The truth is about twenty vitamins, minerals, and proteins are removed in the course of processing, and only eight are returned in synthetic form. Two life-giving elements of the whole wheat kernel are also removed in the refining process. They are the wheat germ and bran. But what exactly do these elements do and why are they important to our diet? Bran is the outer layer of the grain that contains the fibre. It is rich in folic acid and minerals, especially iron and protein. The wheat germ is the richest source of the natural vitamins; niacin, riboflavin, potassium, magnesium, iron, zinc, copper, manganese, and Vitamins E and K. In addition, wheat germ is necessary for the absorption of Vitamin A and for general vitality. It is also known as one of the best sources of natural Vitamin B Complex and high-quality proteins. What is left of the wheat grain is mostly the starchy endosperm. Other factors determining the glycaemic index include:
(a) Type of starch. Some carbohydrates are more difficult to break down to smaller glucose molecules.
(b) The physical form. Finely ground grains, as found in Semovita, are more rapidly digested and therefore have a higher glycemic index than eba.
(c) Ripeness. Ripe fruits and vegetables have higher glycemic index than unripe ones because of the high composition of simple sugars.
(d) Fat and acid content. The more fat or acid contained in the carbohydrate, the slower the rate of breakdown into sugar and absorption into the bloodstream.
Some of the listed factors combine to create counter-intuitive results. So, foods containing complex carbohydrates, such as potatoes, quickly raise blood sugar levels, while some foods that contain simple carbohydrates, such as whole fruit, raise blood sugar levels more slowly. The basic message behind understanding the glycemic index is to replace the highly processed grains, cereals, and sugars with minimally processed whole-grain products. Once, potatoes were listed on the list of preferred complex carbohydrates, but now we all know that they fall into the list of meals to be taken occasionally because of their high glycaemic index.