There are quite a few different types of starches which are either poorly digested or not digested at all. Most types of undigestible carbohydrates are known for being associated with physiologic effects. They may also be held responsible for affecting the contribution of energy to the diet of a person. The scientific world still has many troubles when it comes to understanding, measuring and defining different types of starches and dietary fibers. This has proven to be rather tricky for all those who are responsible for the formulation of recommendations and policies which concern certain types of carbohydrates and their energy values.
Energy value of carbohydrates
The amount of energy contained in the food items can be determined by using various different types of methods. The metabolizable energy is commonly less than the total amount of energy in any food item, because not all the energy can get absorbed and some of it gets lost in the urine. There are certain amounts of energy which get lost in the feces, gases and heat which is associated with the process of colonic fermentation.
Digestion and absorption of carbohydrates
Oligosaccharides and polysaccharides need to be hydrolyzed before being absorbed so that they become monosaccharides, which are much easier for absorption. In case of starches, the digestion begins with the activity of the salivary glands, but its most important part takes place in the small intestine. The digestion and absorption of carbohydrates in cases of most Western diets takes place in the upper small intestine and it tends to be quite fast. Of all different types of monosaccharides, only D-galactose and D-glucose can be absorbed once they get into the small intestine. There are certain types of transporters which are in charge of transporting fructose, galactose or glucose to all the different types of body cells. If a person ingests excessive amounts of fructose, he or she usually experiences certain symptoms such as diarrhea or abdominal flatulence. The situation with disaccharides is completely different. There are a large number of people who belong to the non Caucasian population which suffer from lactase deficiency. Such deficiencies may be partial or even complete in some cases and they are often characterized by significantly reduced abilities to absorb or digest lactose.
The Glycemic Index
The glycemic index is a certain type of value which defines the blood glucose response of various different types of carbohydrate foods. It is rather difficult to determine the glycemic index of various different types of mixed meals.