Carbohydrates are those foods that are broken down to sugars. There are different types of sugars that vary according to their chemical structure. Simple sugars, or monosaccharides, consist of glucose, fructose, mannose, galactose, and xylose. These sugars are very easily digested and absorbed. Disaccharides are simple sugars composed of two monosaccharides. Sucrose is a disaccharide consisting of fructose and glucose. Lactose is made up of glucose and galactose, while maltose is composed of 2 molecules of glucose.
Polysaccharides are made up of 10 or more molecules. Some of these escape digestion and absorption, and enter the large intestine as short change fatty acids. Mono- and disaccharides, since they are simpler, are more easily absorbed, as are some complex carbohydrates. Once these sugars hit the blood stream, insulin is secreted to facilitate storage of the sugar, or glucose, in the tissues. Sometimes the insulin response is too great, resulting in an over-secretion of insulin, causing hypoglycemia. Signs and symptoms of hypoglycemia include headache, sweating, nausea, fatigue and confusion. These symptoms can be very mild or severe depending on the individual response.
Cancer relates to this situation in that insulin has a growth-stimulating effect on cells. There is growing evidence that increased insulin in the blood may increase the risk of certain tumors, such as cancers of the colon and pancreas. Also, increased sugar intake weakens the immune system, which has the ability to recognize tumor cells and destroy them.
The ease with which a carbohydrate is metabolized and converted into blood sugar is measured by the glycemic index. Foods with a high glycemic index, such as a baked potato, are converted quickly into blood sugar, where as foods with a low glycemic index, such as lentils, are converted into blood sugar more slowly. The reason this is important is that foods with a high glycemic index are converted quickly to blood sugar and result in the rapid production of insulin. At times, this insulin production is excessive, resulting in the hyperinsulinemia tied to an increased risk of cancer as described above.