!44: Digestion and Absorption of Carbohydrates

!±8± Digestion and Absorption of Carbohydrates

The digestion of carbohydrates begins in the mouth, for the teeth and tongue to perform mechanical digestion, while amylase, a salivary enzyme, begins the chemical digestion. Both the mechanical and chemical processes of digestion are necessary to initiate the breakdown of the food. As the food reaches the stomach, the digestive processes temporarily stop due to the acidic conditions of the stomach which inhibit the activity of salivary enzymes. When the food reaches the small intestine, pancreatic amylase and oligosaccharides from the small intestine continue the digestion process until the carbohydrates are reduced to monosaccharides and are absorbed.

After being absorbed in the small intestine, the monosaccharides enter the bloodstream where they are: transported to cells that require them for energy, stored in the liver or muscles for later uses of energy, or remain circulating in the blood awaiting future transportation to a cell. When excess amounts of carbohydrates are circulating in the blood, they may be transported to adipose tissue to be stored as fat.

Sugar substitutes are created to allow food to digest easier, while alleviating a number of the problems that occur with sugar ingestion; such as an increase in blood glucose, increase in caloric intake, and promotion of tooth decay. Sugar alcohols are often used to solve the problem of tooth decay. Sorbitol and Xylitol are examples of sugar alcohols. Another group of sugar substitutes that are non-caloric and non-promoters of tooth decay include aspartame and saccharine. Actually, both aspartame and saccharine contain 4 calories per gram, but both products are approximately 200 to 400 times as sweet as sucrose; therefore, in the amounts consumed, their caloric content is virtually nothing. These help digestion because they lower the density of the enzymes involved in the digestion process, allowing them to work faster. As many people consume sugar substitutes to reduce caloric intake, an important question recently raised is whether consumption of sugar substitutes is healthy. Today, the use of sugar substitutes has never been associated with an increase in caloric intake or a gain of weight in humans. There are, however, some health issues that need to be kept in mind when consuming sugar substitutes as some people have adverse reactions to them, and the effects of long-term use of the products are not yet known. Despite the advantages in digestion, most people should limit their consumption of any sugar carbohydrates, and even sugar substitutes.