Carbohydrates are the most important nutrients in humans besides fats and proteins. They are formed from the substances carbon, water, and oxygen, through photosynthesis, in the plants using solar energy and chlorophyll.
Carbohydrates can be divided into:
- Simple sugars (monosaccharides):
- Glucose, fructose, galactose
- (Low molecular weight)
- Double sugar (disaccharides):
- Sucrose, lactose, maltose
- (Low molecular weight)
- Multiple sugars (polysaccharides):
- Starch, glycogen, cellulose
- (High molecular weight)
The various carbohydrates of food are converted into glucose in the body. From glucose, cells can also synthesize other sugars for specific tasks. The carbons are in the body in a constant assembly and disassembly.
Tasks of carbohydrates in the body:
- Carbohydrates are the main source of energy for the organism. 1 g of carbs provides 4.2 kcal of energy. Almost all cells use glucose as an energy source. The brain cells and the erythrocytes (red blood cells) rely solely on glucose as an energy source. With a surplus of energy from carbohydrates, the surplus is converted into fat and stored in the body. When storing carbohydrates as body fat, about 30% of the energy is lost.
- Another important function of carbohydrates is that of a reserve substance. In the form of the body’s own glycogen, carbohydrates represent readily available reserve energy. A person weighing 70 kg has a glycogen reserve of about 350 – 400 g, which corresponds to about 1,500 kcal. The glycogen supply is about 1/3 stored in the liver and about 2/3 in the muscles.
- The fiber is also carbohydrates. It used to be thought that they were not usable by the human body because human digestive juices contain no enzymes that can break these compounds. It has been overlooked that some of the dietary fiber is fermented by enzymes of the microorganisms of the large intestine. In addition to gases, short-chain fatty acids, which can be utilized by humans, are also produced. The energy gain from dietary fiber is negligible due to the small amounts supplied. The intake recommendation of the DGE of 30 g fiber per day is often not reached.
Feed recommendation for carbohydrates:
Since carbohydrates and fats can be widely represented as energy suppliers, there are no exact intake recommendations. For a normal fat metabolism daily 60 – 100 g carbohydrates are necessary. If too little energy is supplied in the form of carbohydrates and fats, protein is broken down instead of the energy carrier. One speaks therefore of the protein-saving effect of the carbohydrates.
The DGE recommends covering at least 50% of the energy needs of carbohydrates.
Starchy, high molecular weight carbohydrates should be preferred. Consumption of low molecular weight carbohydrates should be reduced.
Carbohydrates in food:
1.) Simple sugars (monosaccharides)
Galactose (mucus sugar)
2.) Double sugar (disaccharides)
Sucrose (beet and cane sugar)
- sugar beet
- Table sugar, candy
Lactose (milk sugar)
- Dairy products
Maltose (malt sugar)
- malt extract
3.) Multiple sugars (polysaccharides)
- all plants