Carbohydrate is a compound basically formed by carbon (C), hydrogen (H) and oxygen (O). Therefore, chemically, it is called carbohydrate, whose general formula is Cx(H2O)y.
These are abundant biomolecules in nature, also called carbohydrates or sugars, which range from the sugar we use to sweeten to the cellulose present in plant cells.
The 3 Main Functions of Carbohydrates
1. Energy supply
Human beings get energy through food. When ingested, carbohydrate is broken down by specific enzymes into smaller sugar units until glucose is produced.
In cells, energy is obtained from glucose, according to the global equation below.
Ç6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy
This released energy is used, for example, by the nervous system, with the brain being the main consumer. The energy of neurons comes almost exclusively from glucose.
2. energy storage
Plants have a green pigment called chlorophyll, which is able to absorb light energy from the sun.
Using carbon dioxide from the air and water captured by the roots, plants are able to convert solar energy into chemical energy in the photosynthesis process.
Photosynthesis takes place according to the following chemical reaction.
6 CO2(g) + 6 H2O(1) + sunlight → C6H12O6(aq) + 6 O2(g)
Glucose molecules (C6H12O6) produced combine to form starch, the polysaccharide responsible for energy storage in plant organs.
3. cell structuring
The plant cell is the forming unit of plant tissue, consisting of organelles and genetic material, delimited by a cell wall.
The main component of the cell wall is cellulose, a polysaccharide composed of numerous glucose molecules.
Cellulose makes plant cells have a fixed structure, which is responsible for protection, support and resistance. This carbohydrate also regulates the access of water to the cell and the interaction between neighboring cells.
To acquire more knowledge read: carbohydrates or carbohydrates: what are they?
Carbohydrate classification
According to the size of the chain and its complexity, carbohydrates can be classified into:
- monosaccharides
- oligosaccharides
- Polysaccharides
Monosaccharides, also called aces, are simpler carbohydrates and, therefore, do not undergo hydrolysis. Oligosaccharides and polysaccharides correspond to osidium, complex carbohydrates that can transform into smaller molecules when they are hydrolyzed.
1. monosaccharides
They are carbohydrates made up of aldoses, which have the aldehyde group (-CHO) in the chain, and ketoses, which have the ketone functional group (C=O).
According to the number of carbons, monosaccharides are classified into trioses (3C), tetroses (4C), pentoses (5C), hexoses (6C) and heptoses (7C).
Examples:
Glucose is an aldohexose produced in photosynthesis. Fructose is a ketohexose found in fruits.
Learn more about monosaccharides.
2. oligosaccharides
Oligosaccharides correspond to soluble carbohydrates formed by more than one monosaccharide joined by O-glycosidic bonds.
This group includes disaccharides, the junction of two monosaccharides, and trisaccharides, which correspond to the union of three monosaccharides in one molecule.
Examples:
Maltose is a disaccharide that is part of the malt used in beer production. Raffinose is a trisaccharide found in foods such as beans.
Learn more about disaccharides.
3. Polysaccharides
Polysaccharides are several monosaccharides joined by glycosidic bonds in a long polymer chain.
Examples:
- Starch: energy reserve of vegetables.
- glycogen: animal energy reserve.
- Cellulose: structural component of the plant cell wall.
The three polysaccharides above are polymers that have a molecular formula (C6H10O6)no, as they are formed by the union of several glucose molecules.
Learn more about polysaccharides.
The main sources of carbohydrates for food
Carbohydrates are mainly found in vegetables, as they are one of the products of photosynthesis. However, animal products can contain carbohydrates, such as milk that has the sugar lactose.
Carbohydrates are one of three groups of macronutrients, along with proteins and fats, that need to be included in the diet as the body does not produce them. Regardless of its source, for every 1 g of carbohydrate consumed, 4.02 kcal is provided.
In food, the calories consumed during a day should correspond to 45% to 65% carbohydrates. The recommended daily amount is 135 grams. This intake varies if the person suffers from illnesses such as diabetes or has other conditions such as pregnancy.
Simple Carbohydrates vs. Complex Carbohydrates
Simple and complex carbohydrates differ in structure and, therefore, are absorbed in different ways by the body. Simple carbohydrates, made up of one or two sugars, generally digest quickly, whereas complex ones take longer.
Simple carbohydrates are present in foods classified as processed, which lack vitamins, minerals or fiber. Therefore, they are called "empty calories" and can lead to weight gain. Are they:
- Cake
- Candy
- Soda
- Ice cream
- French fries
Complex carbohydrates have more than three sugars and are rich in starches. Check out some examples below.
- Bean
- Lentil
- Potato
- Corn
- Cereals
It is noteworthy that, because they are absorbed quickly, simple carbohydrates cause a great amount of energy in a short time, while complexes have energy released continuously.
Good Carbohydrates vs. Bad Carbohydrates
Generally, carbohydrates are classified as good or bad for their nutritional value. Analyzing the composition of foods, good carbohydrates differ from bad carbohydrates in that they have:
- Moderate amount of calories
- Lots of nutrients
- lots of fibers
- low sodium
- low saturated fat
- Absence of trans fat
Foods found in nature, such as vegetables, are associated with good carbohydrates. Processed and sugar-rich products, such as soft drinks, are classified as bad carbohydrates.
Carbohydrate excess x carbohydrate deficiency
Excess carbohydrates in the diet, especially refined ones, are broken down by enzymes in the intestine and quickly transformed into glucose.
This can turn into a vicious cycle in the body, as insulin production is stimulated due to the increase in the amount of sugar in the blood. Insulin, in turn, rapidly lowers the blood glucose level, which can lead to a feeling of weakness and even more hunger.
On the other hand, the lack of carbohydrates in the body causes body fat to be used as an energy source.
However, carbohydrate is important in the fat burning process and without it, the process is incomplete, causing the formation of toxins that can lead, for example, to a decrease in blood pH and dehydration.
Another alternative energy source to carbohydrates is protein, used for muscle production. When the body uses proteins as fuel, this can put stress on the kidneys.
Test your knowledge with questions about carbohydrates.
