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Difference Between Essential and Nonessential Amino Acids

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Introduction to Essential and Nonessential Amino Acids

In this article, we will discuss the difference between essential and non-essential amino acids. An amino acid is a biomolecule that combines to form proteins and therefore, both amino acids, as well as proteins, are the building blocks of life. Amino acids are left after the breaking down or digestion of proteins, also, the human body utilizes amino acids to produce proteins that help in breaking down food, growing, repairing body tissue, and performing various body functions. Therefore, amino acids are also referred to as basic building blocks of proteins.


What are Amino Acids?

The fundamental units of proteins are amino acids, the polymerization of amino acids yields proteins. There are 20 macromolecules that make up amino acids. Amino acids are organic compounds with a carbon side chain, an amino group, and a hydroxyl group. All amino acids have the same fundamental structure, however, their carbon side chains differ. The polarity, charge, molecular weight, and activities of amino acids vary from each other. Peptide bonds link amino acids to create polypeptide chains, these are then arranged into secondary and tertiary structures of proteins. Proteins differ in chain length, amino acid sequence, characteristics, and function. The limitless combinations of various amino acids provide distinct proteins with a considerable deal of variability.

Proteins serve a variety of purposes. Collagen, a structural protein that forms feathers, hair, and horns, is found in the structural proteins of animal connective tissues. Albumin in eggs and proteins in plant seeds are examples of storage proteins. Hemoglobin and other transport proteins transfer things throughout the body. Hemoglobin carries oxygen to all of the body's cells and carbon dioxide to the two lungs for gas exchange. Hormonal proteins control a variety of bodily functions. The insulin hormone, for example, keeps blood sugar levels in check.

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Classification of Amino Acids 

Since we have developed a basic understanding of what amino acids are, let us look into the classification of amino acids. Amino acids can be classified into three groups, namely essential amino acids, nonessential amino acids, and conditional amino acids. 

Essential Amino Acids: 

Amino acids which cannot be synthesized or produced by the body and are required from food supplements are called essential amino acids. There are 9 essential amino acids that include leucine, isoleucine, histidine, lysine, methionine, threonine, phenylalanine, tryptophan, and valine.

Non-Essential Amino Acids:

Amino acids which are produced or synthesised by our bodies and are not taken up as food supplements are called nonessential amino acids. There are 20 total amino acids common in all life forms and the nonessential amino acids out of these include arginine, alanine, aspartic acid, asparagine, cysteine, glutamine, glutamic acid, proline, glycine, serine and tyrosine. Without these amino acids, our body will find it hard to make up proteins it needs which are required for the repair, growth and maintenance of cells.

Conditional Amino Acids: 

Some of the amino acids which are usually not essential but in times of illness and stress, may become essential are called conditional amino acids. These may be required in conditions such as prematurity in infants. The six conditional amino acids include cysteine, arginine, tyrosine, glutamine, ornithine, glycine, serine, and proline.


Difference Between Essential and Non-Essential Amino Acids

Mentioned below is the table that summarizes the main parameters based on which amino acids are classified.


Essential Amino Acids

Non-essential Amino Acids


These cannot be made by the body therefore, these are required through our diet or food supplements.

These can be made by our body or are always available.


9 essential amino acids are known out of 20 amino acids.

11 out of the 20 amino acids are known to be non-essential amino acids. 

Food sources

Various sources of food that provide essential amino acids include quinoa, egg, meat, chicken and vegetable protein.

These can be produced within our body from other amino acids and their components as well.


These function in building and repairing muscle tissues and they form precursor molecules for neurotransmitter formation in the brain. 

These are very helpful for the removal of toxins, promoting brain functioning and synthesising RBC and WBC in our bodies.

Deficiency known

The deficiency of these amino acids is highly probable as these are provided with the help of food and a proper diet. 

Deficiency of these amino acids is rare as can be produced by the body, however, in case of starvation and illness, deficiency may be seen.


Leucine, isoleucine, histidine, lysine, methionine, threonine, phenylalanine, tryptophan and valine

Arginine, alanine, aspartic acid, asparagine, cysteine, glutamine, glutamic acid, proline, glycine, serine and tyrosine.

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FAQs on Difference Between Essential and Nonessential Amino Acids

1. What are Amino Acids?

Amino acids are the building blocks of protein that form polypeptides and ultimately proteins. These are responsible for vital physiological functions in our body due to protein synthesis, major functions such as tissue repair, nutrient absorption, and bodybuilding.

2. How many Amino Acids are known to exist?

There are 20 amino acids, out of which 9 essential amino acids and 11 nonessential amino acids are known. The former kind of amino acids are required from the diet we consume whereas the latter or nonessential amino acids are synthesised by our own body.

3. What is the recommended daily intake of Amino Acids?

The recommended daily intake of essential amino acids for children is 10-20 percent higher than adult levels and for infants, it's 150 percent higher in the first year of life. The three major amino acids suggested for infants and growing children are cysteine, tyrosine, and arginine. The daily intake of histidine, isoleucine, leucine, and lysine are 10, 20, 39, and 30 mg per kg body weight, respectively. It is the figure provided by the World Health Organization.

4. Name the source of food for Lysine, Tryptophan and Methionine?

We can find lysine in wheat, rice, and maize; tryptophan in maize and legumes; methionine is present in legumes.

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