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 an organic compound 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, grow, repair body tissue and perform various body functions. Therefore, amino acids are also referred to as basic building blocks of proteins. 

Classification of Amino Acids 

Amino acids can be classified into three groups, namely essential amino acids, nonessential amino acids and conditional amino acids.  

  1. Essential Amino Acids: Amino acids which cannot be synthesised 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.

  2. Nonessential 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.

  3. 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. 

Our body does the mixing of 20 different amino acids and mixing and matching them together in a bonded chain. When we eat meat, fish, poultry, eggs and plant proteins, these foods get broken down in the digestive tract into individual amino acids and reassembled in our body to form a wide variety of proteins.

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Difference Between Essential and Nonessential Amino Acids

Essential Amino Acids

Nonessential 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 vegetables 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 neurotransmitters 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

Deficiency of these amino acids is highly probable as these are provided with the help of food and 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.

FAQs (Frequently Asked Questions)

1. What are Amino Acids?

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

2. How many Amino Acids are known to exist?

Ans. 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?

Ans. The recommended daily intakes 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 ife. 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?

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