Carbohydrate facts to be aware of.
Simple carbohydrates – glucose, galactose (a component of milk sugar) and fructose – are easily used by the body, absorbed immediately through the intestinal lining and released into the bloodstream. Complex carbohydrates undergo more complex transformations. To be used by the body, they must first be digested. The digestion process takes place in the alimentary canal, namely the mouth, stomach and small intestine.
Complex carbohydrates are digested by enzymes in saliva, intestinal fluid and in the digestive juices of the pancreas. Complex carbohydrates also include non-digestible dietary or dietary fibre in the diet. These are resistant to the action of digestive enzymes and are virtually unavailable. They play an important role in various diets and in weight loss.
Digestive enzymes get their name from the carbohydrate they are responsible for digesting.
For example, sucrose (beet sugar) is digested by the enzyme sucarase, and fructose is digested by the enzyme fructase, etc. These enzymes are extremely important. For example, lactose intolerance is a disease caused by a deficiency of the enzyme lactose. If our body lacks the milk-digesting enzyme lactase, we cannot digest milk and dairy products.
Energy reserves
Digestible carbohydrates are converted into simple sugars in the digestive tract and then absorbed in the small intestine, from where they pass directly into the blood. From the blood, they pass through the hepatic capuwen to the liver. Glucose that is not used by the body is stored by the liver in the form of glycogen (a complex sugar made up of hundreds of glucose molecules linked together in a chain).
The liver redistributes its ‘energy reserves’ according to the body’s needs, glucose is released into the bloodstream through glycogen breakdown, so that the carbohydrate needed is delivered to all the cells of the body. Of course, the liver only steps in when it really has to, because it is not an inexhaustible reserve. Without carbohydrate replenishment, the balance is upset.
However, the body can only store a certain amount of glucose. Excess glucose – that which the body does not use immediately – is converted into fat, leading to obesity.
Carbohydrates and hormones
In a healthy body, blood glucose levels depend on the interaction of the different hormones that regulate it. The pancreatic hormones, insulin and glucagon, are produced by the endocrine gland of the pancreas, the so-called islets of Langerhans. When large amounts of carbohydrates are suddenly released into the body (for example, by eating sugary foods or drinks), the pancreas releases a corresponding amount of insulin into the blood.
So insulin levels are increased, which lowers the excessively high blood glucose levels and also stimulates glucose to enter the cells so that it can be converted into glycogen or fat. As blood glucose levels fall, glucagon goes into action. As a result of its action on the liver, glucose is mobilised from glycogen stores, causing blood glucose levels to rise. In addition to pancreatic hormones, certain adrenal hormones also affect sugar metabolism.
