Carbohydrate Digestion and Absorption

During exercise, for the most part, carbohydrates are broken down to their component monosaccharides during the process of digestion, resulting in release of fructose, galactose and mostly glucose (dextrose) in the small intestine. These sugars are then absorbed through the intestinal wall into the bloodstream, and then are taken to the liver. Glucose (dextrose) requires no processing, and is released into the bloodstream for use as quick energy Fructose and galactose are converted to glucose in the liver before they are released into the bloodstream. This process takes time, however, and therefore fructose and galactose are not ideal carbohydrates for use in sport, especially in the heat, where a steady supply of readily available carbohydrate is a must.

Furthermore, regarding fructose, this carbohydrate is a known irritant to the gastrointestinal tract. A lot of sports drinks and sports nutritional products contain this carbohydrate, contributing to gastrointestinal distress, especially in the heat.

Finally, some carbohydrates escape full digestion, passing into the large intestine. This contributes to flatulence, abdominal cramping and bloating. It can also cause diarrhea, and hence contribute to dehydration. The carbohydrates most likely to be associated with this phenomena are polysaccarides such as maltodextrin, glucose polymers, amylopectin and amylose.

Stay tuned to find out about a newer classification system for carbohydrates. You may also subscribe to this site in order to get automatic updates.