What are amino acids?

Published on March 22, 2023

Amino acids are organic compounds that combine to form proteins of every living matter. Amino acids are used by the organism for building blocks of proteins.

When proteins are digested or broken down, amino acids are left. The human body uses amino acids to make proteins to help the body break down food, grow, repair body tissue and perform many other body functions.

Amino acids: three groups

All the proteins of every living creature are formed by only twenty-two amino acids which are classified in three groups : the essentials, the nonessentials and the conditionally essential ones.

Nine of the twenty-two protein amino acids that are necessary to the human or animal body cannot be synthesized by the organism, they need to be found in protein foods eaten and are called essential amino acids.

These essential amino acids such as lysine and methionine can be found in animal and plant-based feeds. We also need to find other essential acids in food such as fatty acids that our body cannot synthesize. These fatty acids can be found in palm, nut or flaxseed oil, in eggs, milk or in several fishes (anchovy, salmon, tuna…).

There are twelve nonessential amino acids that are synthesized by the organism from the essential ones; they are also called conditional amino acids. These nonessential amino acids are for example arginine, cysteine, glutamine, glycine, aspartic acid and proline.

The twenty-two amino acids include ones that are said to be conditionally essential amino acids or conditional amino acids, they are so-called because they are usually considered as nonessential but become essential when an individual cannot produce enough of them in case of illness or disruption of the organism.

For example cysteine, glycine and arginine become essential for a premature infant because it cannot produce enough of them.

Ten amino acids to know individually

Proteins and the amino acids contained in it are crucial for the construction and the restoration of the whole organism but the main roles of some of them can be defined individually as follows :

Lysine is an essential amino acid.

It assumes main physiological functions and is responsible for the production of diverse hormones, enzymes and antibodies. It contributes, for example, to bones growth and the creation of collagen.

It can be found in meat, eggs, milk products but also in leguminous plants. It can be used to cure some viral diseases such as skin problems. Recently, scientists have discovered its anti-cancer action.

Methionine is a sulfurated essential amino acid.

It needs to be associated with B12 vitamins to be synthesized and assimilated. It assumes main roles in the organism such as protein formation, synthesis of certain hormones, development of liver, kidney and muscle cells and DNA methylation.

It can be found in nuts, beef, cheese, chicken, pork, fish and eggs. It can be used to cure osteoarthritis and hair loss among other illnesses.

Arginine is a nonessential amino acid.

The human body can only synthesize a small amount of it but it can easily and largely be found in feeds that we eat such as meat, leguminous plants, cereal, nuts and milk products. It contributes to cell division, wound healing, supports the immune system and acts in the ammonia excretion.

It contributes to the creation of creatine which is associated with the development of muscles. Premature infants cannot synthesize it. It can be used to cure sexual disorder such as erectile dysfunction .

Aspartic acid is a nonessential amino acid.

It assumes several functions of the organism such as protein formation but also metabolic response. It contributes to testosterone and progesterone production and acts as a neurotransmitter in the brain as it activates glutamate receptors.

It can be found in turkey, beef, bacon, fish, lentils, veal and chicken . It can be used to boost male’s fertility and increase tolerance to tiredness in case of intense physical exercise. It is also used as an active principle to improve minerals absorption.

Glutamic acid is a nonessential amino acid.

The human body can only synthesize a small amount of it but it can easily be found in feeds such as almond, krab, chicken, parmesan, pumpkin seeds, coral lentil and beef. In the organism, this amino acid is responsible for neurotransmission in the brain.

Glutamate (a ionized form of glutamic acid).

It is one of the most important neurotransmitters of the central nervous system.

Glutamine (derived from glutamic acid).

It is often used by high-level athletes to rapidly reconstitute their glycogen stocks. It can be used to increase the level of energy, improve performances and enhance post-effort recovery.

Proline is a nonessential amino acid synthesized by the organism from glutamic acid.

Proline contributes to the metabolization of collagen which is essential for the tendons, skin and knuckles.

Cysteine acid is a nonessential amino acid composed of two molecules of the sulfurated amino acid cystine.

It assumes several main roles in the organism and intervenes in the biosynthesis of several proteins. It can also be found in beer yeast, wheat germ, garlic, fishes, meats, eggs and seafood.

This chemical compound is responsible for the production of melanin, the natural pigment that protects the skin from solar UV, keratin (main component of danders), and collagen (material that maintains skin elasticity).

Glycine is a nonessential amino acid.

As a neurotransmitter it acts as an inhibitor in the spinal cord. It plays a role in the metabolization of creatine and so contributes to muscle recovery.

As an antioxidant it contributes to slow down cellular ageing. As a detoxifier it contributes to the synthesis of bile acids. It also intervenes at the brain level where it acts as a calming neuro-mediator and so that favors the restful sleep.

It can be found in veal, wheat, chicken, fish, almond, beef, pork, spirulina, cod and turkey. It also contributes to wound healing.It plays a role in the metabolization of creatine and so contributes to muscle recovery.

As an antioxidant it contributes to slowing down cellular ageing. As a detoxifier it contributes to the synthesis of bile acids. It also intervenes at the brain level where it acts as a calming neuro-mediator and so favors restful sleep.

Amino acids can be at the core of often little-known diseases

Inherited diseases of amino acid metabolism (transformation) may be due to a disorder in the degradation of amino acids, or to an abnormality in the transfer of amino acids into cells. These abnormalities cause symptoms from the first days of life, and newborns are often screened for several common diseases involving amino acids.

For example, children with maple syrup urine disease fail to metabolize leucine, isoleucine, and valine. The byproducts of these amino acids accumulate causing neurological symptoms, including seizures and mental retardation.

Vitamin B1 (thiamine) injections are beneficial for children with mild illness. Once the disease is controlled, children should continue to eat a strict artificial diet low in leucine, isoleucine and valine.

Most of the amino acids can be found in food or are synthesized by the organism but it is possible to bring them into the human organism by other means.

They can be taken in the form of food complement proposed by several pharmaceutic groups which provide amino acid supplements to people who want to buy them for several reasons or they can be prescribed by a doctor in case of deficiency .

This use must be carefully supervised because an oversupply of amino acid can be as dangerous for the organism as a deficiency of it.