Amino acids are known as the basic units or building blocks of proteins. Several types of amino acids can be found in our body, and each of them performs some crucial functions. Find out more about these nutrienst, their types, benefits, and food sources, in this NutriNeat article.
Known as the building blocks of proteins, amino acids are the molecules that contain amine and carboxylic acid functional groups, with a side chain that differs among different amino acids. Their basic constituent elements are, carbon, oxygen, hydrogen, nitrogen, and sometimes, sulfur.
These compounds are the basic units of proteins. To be more specific, a protein molecule is a linear chain of amino acids linked by peptide bonds. In nature, hundreds of amino acids exist, of which 20 are generally found in the human body. These nutrients are critical for life, and they are literally used by every cell of the body to carry out a number of metabolic functions.
Types
The first amino acid to be discovered was ‘asparagine’, which was isolated as a compound of asparagus in 1806 by two French chemists, Louis-Nicolas Vauquelin and Pierre Jean Robiquet. Afterwards, more and more of these compounds were isolated and identified. Out of these, 20 compounds are commonly found as the components of proteins and peptides in the human body, which are classified into two main groups – essential and non-essential amino acids.
Generally, 8 of them (phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine, and lysine) are classified as the essential amino acids, for the reason that they cannot be synthesized by our body. So, they have to be obtained from food or supplements. Arginine, cysteine, glycine, glutamine, histidine, proline, serine, and tyrosine are considered to be conditionally essential. This means that they are usually not required to be obtained from the diet, but at times, they may not be produced in sufficient amounts. In such a situation, they have to be obtained from food or supplements.
On the other hand, tyrosine, histidine, and arginine are considered essential for infants and young children, as their body cannot synthesize these nutrients in adequate amounts. However, the distinction between essential and non-essential amino acids is not very clear. In general, arginine, alanine, cysteine, glutamate, glutamine, aspartate, glycine, asparagine, serine, and pyrrolysine are considered as the non-essential amino acids. Out of all amino acids, leucine, valine, and isoleucine are called branched-chain amino acids.
Functions
As the basic units of proteins, amino acids are vital for protein synthesis. They are used by the body for building and repairing muscles, ligaments, tendons, skin, hair, and nails. They are required for cell growth, enzyme synthesis, the synthesis of antibodies and hemoglobin, and also for supporting the various biochemical processes required for sustaining life. Some of these compounds also act as neurotransmitters, while others facilitate the functions of the vitamins and minerals.
L-arginine
It is important for maintaining the health of the cardiovascular system. It assists liver detoxification, along with maintaining a healthy immune system. It is required for the release of growth hormones as well. It may prove helpful in kidney disorders.
L-lysine
L- lysine or lysine is important for the growth and repair of the muscles. Along with vitamin C, it plays an important role in collagen formation. This essential amino acid facilitates the absorption of calcium, and the production of antibodies, enzymes, and hormones. It can lower the levels of triglycerides in the body, and may prove effective in treating cold sores and genital herpes.
L-cysteine
Cysteine can protect the body cells from the highly reactive free radicals. It can promote the process of detoxification, besides providing protection against copper toxicity.
L-glycine
Glycine takes part in the production of glycogen, which is then stored in the liver. Glycogen is broken down to glucose whenever the body is in need of energy. Glycine also supports and strengthens the immune system.
Tyrosine
It is basically required for the synthesis of catecholamines, such as dopamine and noradrenaline. It has been observed that individuals suffering from depression usually have low levels of tyrosine. This is the reason why, it is sometimes used in the treatment of depression.
L-histidine
This compound is the precursor of histamine, which is the chemical released by the immune system during an allergic reaction. Histidine dilates the blood vessels, and it has been found to be effective in reducing the symptoms of rheumatoid arthritis.
Leucine
This branched-chain amino acid helps reduce the breakdown of muscle proteins. It can facilitate the healing of broken bones as well.
Glutamine
It is the most abundant amino acid found in the muscle tissues. It serves as an important source of energy. Glutamine also supports the immune functions of the body.
Isoleucine
It provides energy to the muscles, and prevents muscle wasting or breakdown. It plays an important role in the formation of hemoglobin as well.
Methionine
Methionine is the precursor of cysteine and creatine. In other words, our body can synthesize these two compounds from methionine. In addition to these, methionine can help remove toxic substances from the liver, and facilitate the regeneration of liver cells. It may help reduce the level of blood cholesterol.
Tryptophan
It is essential for maintaining the rate of growth and metabolism. Tryptophan is the precursor of the neurotransmitter, serotonin. Serotonin is known to calm the central nervous system. A low level of serotonin is often associated with conditions like depression.
Food Sources
Amino acids are basically found in animal food sources. So, meat, eggs, poultry, fish, and milk and dairy products are some good sources of these nutrients. These are known as the complete sources of proteins, as they contain all the essential amino acids.
Most of the plant food sources on the other hand, cannot provide all the essential amino acids that are required by the human body. This is the reason why, vegetarians are generally advised to include a variety of plant food in their diet. For vegetarians, some important food sources of proteins are, beans, pulses, legumes, soy and soy products, and whole grains.
Today, amino acids are largely used for preparing supplements, which are particularly popular among athletes and body builders. They use these supplements for enhancing their performance, and for building muscle mass. Apart from these, these supplements are sometimes used for treating certain conditions like alcoholism, drug abuse, depression, stress, weight loss, eating disorders, and chronic fatigue. They are also used for the production of biodegradable plastics, animal feed, and drugs and cosmetics.
