What are amino acids - simply explained
They are the basic building blocks of proteins and are therefore found in all living organisms. Arginine, cysteine, lysine and co. are involved in many biological processes in the body, especially muscle building. The body can produce many of these compounds itself - but not some. They are known as essential amino acids and must be ingested through food.
What are they made of?
Amino acids are molecules that consist of the chemical elements nitrogen, carbon and oxygen. They are classified as such because they have at least one carboxyl group (-COOH) and at least one amino group (-NH2).
How many of these chemical compounds are there?
There are very many: more than 250 in total. However, only 20 are important for the human body, the so-called proteinogenic amino acids. The term amino acids is often used synonymously with the term proteinogenic amino acids, but this is not technically correct. While only 23 of the latter are known to date, there are a total of 250 amino acids that fulfil different biological functions.
A rough distinction is made between three different classes:
α-Amino acids: In this class, the amino group is located on the second carbon atom. Most proteinogenic amino acids, such as glycine, leucine, tyrosine and glutamine, fall into this α-amino acid class.
β-Amino acids: In this class, the amino group is located on the third carbon atom.
γ-Amino acids: In this class, the amino group is located on the fourth carbon atom.
What are the differences between amino acids?
Chemically speaking, the individual compounds are distinguished by the amino acid residue, a side chain that is also simply called a residue or R. A distinction is also made between proteinogenic and non-proteinogenic amino acids (these are not required for protein biosynthesis). A further subdivision is into non-essential, conditionally essential and essential amino acids. Non-essential amino acids can be produced by the human organism itself. Conditionally essential amino acids only need to be supplemented through the diet in exceptional cases, such as after a serious accident or during growth. Essential amino acids are proteinogenic compounds that the human body cannot produce itself and must therefore be obtained from food. Proteins can only be produced from DNA using the blueprint if the body has sufficient quantities of all of them.
Which amino acids are essential?
Essential amino acids are used to build proteins. The type of proteins produced depends entirely on the chain length and combination. A total of eight of the proteinogenic amino acids are essential amino acids, i.e. those that the body cannot produce itself or can only produce to a small extent. These include valine, methionine, leucine, isoleucine, phenylalanine, tryptophan, threonine and lysine.
Why essential amino acids are so important
Proteinogenic amino acids are the basic building blocks of proteins. When building proteins, amino acids are linked together like a chain: small proteins consist of around 50, large proteins of up to thousands. Proteins are in turn essential for building muscle. Without the most important amino acids, there would be no muscles, to put it simply. But that is by no means all. Proteins fulfil many other important functions, as they are the main components of most cell structures in the body.
How many essential amino acids does the body need?
In total, humans need 21 proteinogenic amino acids, but only eight of these are classified as essential, as the body cannot produce them itself, or only to an insufficient extent. They must therefore be obtained from food, including isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
What are essential amino acids needed for?
As proteins are a main component of cells, they are involved in many vital functions, such as hormone and enzyme production, biochemical reactions, signalling in the body and metabolism. Each of these chemical compounds has its own specific task:
METHIONINE
for example, methionine has the side effect that an excess of methionine acidifies the urine, which inhibits the growth of bacteria and kidney stones. This is why methionine is often used to support antibiotic treatment of urinary tract diseases.
TRYPTOPHAN
is the starting material for the neurotransmitter serotonin and the sleep hormone melatonin. Tryptophan is therefore used to treat sleep disorders, among other things.
LYSINE
is involved in the production of collagen, the structure of connective tissue, cartilage, skin, hair, teeth, bones, vision and muscles.
PHENYLALANINE
is the precursor of the happiness hormone dopamine, which has a positive influence on mood.
LEUCIN
contributes to the maintenance and development of muscle tissue.
ISOLEUCIN
is also involved in muscle development.
VALIN
supports the rapid absorption of all amino acids in the muscles and liver.
THREONIN
is contained in dental tissue and collagen. It also contributes to the normal functioning of the nervous system and liver and regulates the fat balance.
Why do amino acids play an important role in the diet of athletes?
Proteinogenic amino acids help to delay muscle fatigue. This is because if the muscle has all the necessary building blocks such as proteins, it regenerates faster and better after extensive exercise. If a muscle is injured in one area, this is exactly where the amino acids come into play. Strength athletes also like to take special amino acid supplements in addition to conventional foods, as these help to build muscle.
Which amino acids are involved in muscle building?
The most important proteinogenic amino acids required for muscle building are leucine and isoleucine. Leucine is involved in the maintenance of muscle protein and the provision of energy in the muscle. Isoleucine regulates hormone production and activates the growth hormone somatotropin. It also activates the release of insulin, which helps amino acids to reach the muscle cells. It also helps with wound healing.
Which amino acids are found in skin and hair?
Amino acid preparations are not only available for ingestion. Numerous skin creams and hair care products nowadays also contain the building blocks for the proteins found in the skin and hair. Arginine regenerates skin damage, histine soothes irritation and methionine protects against free radicals; the amino acid lysine supports the skin's barrier function; leucine and glycine minimise fine lines. Methionine and cysteine are particularly important for hair, as they are the basic building blocks of keratin, the main protein in hair.
What happens with an amino acid deficiency?
When they are lacking in the body, the effect of proteins is inhibited. As they are involved in almost all biological processes in the body, a deficiency has consequences for immune defence, performance, joints and muscle building. Loss of performance, fatigue, hair loss, muscle weakness, sleep problems, mood swings, blood sugar fluctuations and thyroid problems are just some of the symptoms that can occur. Risk groups for a deficiency are small children, pregnant women, chronically ill people (e.g. high blood pressure or arteriosclerosis), but also people who suffer from stress. Because stress hormones are formed from amino acids, a balanced diet is particularly important at these times.
Which foods contain a lot of amino acids?
They are mainly found in foods and foodstuffs that contain a lot of protein: in animal products such as meat, fish, dairy products and eggs, but also in plant foods such as pulses, cereals, soya beans, potatoes and nuts. A protein-rich diet is therefore important to ensure an adequate supply. If you look at foods made from meat, chicken in particular contains large amounts of isoleucine, beef is high in valine, lysine and leucine and pork is a good source of thiamine.
You can find out which foods are particularly rich in certain amino acids in this food list. With the right food and a healthy, balanced diet, you can ensure a sufficient supply in most cases.
Valine sources
Salmon, tuna, herring, peanuts, white beans, eggs, beef and veal
Threonine sources
Papaya, lentils, wheat germ and soya beans
Sources of lysine
Fish, prawns, lentils, peas, parmesan and pork
Sources of leucine
Salmon, Tuna, white beans, mung beans, gouda, cream cheese, peanuts, beef, veal and eggs
Isoleucine
Salmon, tuna, plaice, peas, peanuts, Chickpeas and beef
Sources of methionine
Salmon, prawns, brazil nuts, sesame seeds, turkey, hard cheese
Sources of tryptophan
Tuna, veal, cheese, pumpkin seeds, pumpkin seeds and beef, cheese, pumpkin seeds, cashews, walnuts, bananas, dates, dark chocolate and spirulina
Phenylalanine sources
Tuna, beef, soya beans, pulses, cereals
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