First things first … What are carbohydrates?
You will find carbohydrates in a lot of foods. They are in healthy and unhealthy foods like in bread, beans, potatoes, pasta, chips, popcorn, milk, soft drinks, alcohol. The most common form of carbohydrates are starches, fibers, sugars. Fiber and starch are complex carbs, whereas sugar is a simple carb.
While you should eat less simple carbs like cookies, juice, bread you should go for the healthier options with more complex carbs like fruits, vegetable, beans, nuts.
Carbohydrates are macronutrients, which means they are one of the three major sources (carbohydrates, fat, protein) for our body to get energy and calories from.
Disaccharides and polysaccharides must be digested before our body can use them, while monosaccharides* do not require digestion. After that, they can be transferred into the bloodstream and be brought to every place they are needed.
The initial digestion of carbohydrates (more precisely the digestion of two types of carbohydrates starts here: starches and dextrins) already starts in your mouth when food gets in touch with salivary amylase. Starch gets broken down in smaller chains like maltose (a disaccharide contains 2 molecules of glucose*). The digestion doesn´t go further than to that point, because we don´t chew the food long enough and the salivary amylase will only have a small impact.
When the chewed food leaves the mouth, the salivary amylase will be inactivated from the acid environment in the stomach. Here the food will not be digested furthermore.
Digestion in the small intestine
The digestion continues when the food reaches the small intestine. Here happens the further breakdown into the smallest units (monosaccharides) by an enzyme called pancreatic amylase. The remaining starches and dextrins are also converted to maltose. In addition, the amylases maltase converts maltose, sucrase converts saccharose and lactase converts lactose into their smallest units.
While a minor amount of substances (e.g. water, small amounts of monosaccharides) have been absorbed in the stomach, the majority will be absorbed in the small intestine.
Osmosis is a process, that makes the absorption through the intestinal membrane happen. Two possibilities are a) diffusion or b) active transport.
a) Fructose, for example, is absorbed with diffusion. That means molecules will move from where a substance is more concentrated to where it is less concentrated.
b) Glucose and galactose, for example, are absorbed by an active transport. Substances from a less concentrated area need an active transport to the more concentrated area. Energy is necessary for this kind of transport and also a carrier is needed. The carrier substance is a protein or lipoprotein.
* monosaccharides, disaccharides, polysaccharides:
monosaccharides: smallest units of carbohydrates, 1 molecule (glucose, fructose, galactose)
disaccharides: consist of 2 molecules monosaccharides (saccharose, lactose, maltose)
polysaccharides: consist of a number of monosaccharide molecules (starch, dextrine, glycogen) and also cellulose (non-digestible)
**glucose: it´s the smallest possible unit of carbohydrates. Therefore it can be transported in the bloodstream very easy and it doesn´t need to be cut down in smaller units.
We have now reached the conclusion that carbohydrates are mainly sugars which have to be digested in order to be usable for our body. And we have also learned that two types of carbohydrates exist. Good and bad ones.
So, eating the right carbs is actually good and also necessary for a good health!