Basics of carbohydrates

Basics of carbohydrates

 

Carbohydrates are the most important nutrients for humans in addition to proteins and fats. They are formed from the basic substances carbon, hydrogen and oxygen. Photosynthesis in plants is one of the providers of carbohydrates. For most cells carbohydrates are an easily utilizable substrate for the supply of energy and for this reason they are the most important nutrient component for humans. In the human metabolism, many carbohydrates can be converted into each other and are precursors for the synthesis of many important substances.

There are four different types of carbohydrates: monosaccharides, disaccharides, oligosaccharides and polysaccharides (or simple sugars, double sugars, multiple sugars). The criteria for this distinction is the length of the corresponding molecular chain.

 

Fig.1: Different types of carbohydrates
Subgroup Sugar type Found in
Monosaccharides Glucose Fruit, vegetables
Fructose (fruit sugar) Fruit, honey
Galactose (milk sugar) Milk
Disaccharides Sucrose (glucose+fructose) Candy, sugar beet, household sugar
Lactose (glucose+galactose) Milk, dairy
Maltose (glucose+glucose) Malt, maltodextrin, corn syrup
Oligo-/
Polysaccharides
Starch Wheat, potato, legumes
Glycogen Liver, muscles

 

Monosaccharides form the smallest carbohydrate units and are no longer dividable. As the smallest unit they also form the building material for all other carbohydrate compounds.

The next largest carbohydrate unit are the disaccharides, which, in simplified terms, consist of two monosaccharides. Mono- and disaccharides are clearly identified as sugars because of their sweet taste. With increasing molecular size, carbohydrates greatly lose this property. In cellulose and starch a sweet taste is no longer present.

Oligosaccharides consist of three to ten monosaccharide units. In human metabolism, oligosaccharides play an important role as part of antigenic structures.

Lastly, polysaccharides consist of more than ten monosaccharide units. The most important polysaccharides are starch, glycogen and cellulose. Glycogen is a particularly important polysaccharide for the athlete (and not only for him), as it is found as energy storage in muscle and liver cells.

Digestion of carbohydrates