How Many Amino Acids Are Necessary to Make Protein?

December 16, 2025 •

2 min read

The human body requires 20 distinct amino acids to create the vast array of proteins essential for life. These organic compounds are the fundamental building blocks, and a deficiency in any of them can impede the body's ability to synthesize functional proteins. Understanding how many amino acids are necessary to make protein is key to appreciating the complexity of human biochemistry and nutrition.

Quick Summary

The human body needs 20 standard amino acids to construct all proteins. This article explains the difference between essential and nonessential amino acids, detailing how they combine to form protein structures and why dietary intake is crucial for maintaining a complete amino acid pool.

Key Points

20 Standard Amino Acids: The human body requires a specific set of 20 standard amino acids to make all the proteins it needs for proper function.
Essential vs. Nonessential: Nine of these are 'essential' and must come from the diet, while the other 11 are 'nonessential' and can be synthesized by the body.
Complete Protein: A single food is considered a 'complete protein' if it contains all nine essential amino acids in adequate amounts, such as meat, eggs, and soy.
Complementary Proteins: Plant-based sources are often 'incomplete' but can be combined throughout the day to ensure all essential amino acids are consumed.
Protein Synthesis Process: Protein synthesis occurs in two main steps—transcription and translation—where the genetic code dictates the sequence of amino acids to be linked together.
Structural Importance: The sequence and folding of amino acids are critical for a protein's unique three-dimensional shape, which directly determines its function in the body.
Deficiency Impact: A deficiency in even one essential amino acid can prevent the body from synthesizing necessary proteins, leading to potential health problems.

The Building Blocks of Life

Proteins are large, complex molecules found in every cell of the body, essential for various cellular processes like enzymatic reactions and providing structural support. They are made up of smaller units called amino acids. While over 300 amino acids exist, humans use a specific set of 20 standard amino acids to build proteins.

The Role of 20 Standard Amino Acids

All 20 standard amino acids are needed for protein synthesis. A protein's specific sequence and folding, determined by its amino acid composition, dictate its function and structure. Without all 20, the body cannot create the necessary range of proteins.

Essential vs. Nonessential Amino Acids

Amino acids are categorized based on whether the body can produce them.

Essential Amino Acids: Nine amino acids, including histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine, must be obtained through diet as the body cannot synthesize them. A lack of any essential amino acid can hinder protein creation.
Nonessential Amino Acids: The body can synthesize the remaining 11 amino acids, such as alanine, arginine, asparagine, and others, from other molecules. Despite being nonessential in the diet, they are crucial for protein structure.

The Importance of a Balanced Diet

Animal products are generally considered “complete proteins” because they contain all nine essential amino acids. Many plant-based foods are “incomplete” but can be combined to provide all necessary amino acids.

How Proteins are Formed: A Step-by-Step Guide

Protein synthesis involves transcribing DNA into mRNA and then translating mRNA into a polypeptide chain on a ribosome. tRNA molecules bring specific amino acids to the ribosome, where they are linked together. The polypeptide then folds into a functional 3D protein structure, essential for its activity.

Comparison of Essential vs. Nonessential Amino Acids


Feature	Essential Amino Acids	Nonessential Amino Acids
Source	Must be obtained from the diet.	Can be synthesized by the body.
Number	Nine.	Eleven.
Synthesis	Body lacks synthesis pathways.	Body has synthesis enzymes.
Dietary Importance	Required from diet.	Important, but not strictly required from diet.

The Consequences of Amino Acid Deficiency

Insufficient essential amino acids can disrupt protein synthesis, leading to various health issues like fatigue, weakness, or malnutrition-related diseases. Therefore, a balanced diet is vital for ensuring an adequate supply of all essential amino acids.

Conclusion

To synthesize protein, the human body needs 20 standard amino acids, including nine essential ones from the diet and 11 nonessential ones it can produce. All 20 are critical for creating the functional proteins that support biological processes. Consuming a balanced diet with complete or complementary protein sources is key to obtaining the full spectrum of amino acids needed for health. For further information, the National Institutes of Health (NIH) offers resources on protein and amino acid requirements.

Frequently Asked Questions

Yes, all 20 standard amino acids are required to build the variety of proteins necessary for the human body's functions. While the body can produce 11 of these, the other nine, known as essential amino acids, must be acquired through diet.

Essential amino acids are those that the body cannot synthesize and must be obtained from food. Nonessential amino acids can be produced by the body itself, though they are still a vital part of protein formation.

Animal-based foods like meat, poultry, fish, eggs, and dairy are excellent sources of complete protein, as are plant-based options such as soy, quinoa, and buckwheat.

Vegetarians and vegans can get all the amino acids they need by eating a varied diet that includes different incomplete protein sources throughout the day, such as combining rice and beans or consuming complete plant proteins like soy and quinoa.

Without sufficient essential amino acids, your body's ability to synthesize proteins is impaired, which can lead to negative health effects like fatigue, slowed growth, or compromised immune function.

Amino acids are linked together by peptide bonds during a process called translation, which takes place in ribosomes. Ribosomes read a genetic blueprint from messenger RNA (mRNA) to assemble the amino acids in the correct sequence.

The lifespan of proteins varies widely, from minutes to years, with an average of 1-2 days in mammalian cells. Protein synthesis is a continuous process that the body uses to replace and create new proteins as needed.