How many amino acids does your body make without thinking about it?

November 17, 2025 •

2 min read

Over 500 amino acids exist in nature, but the human body relies on just 20 of them to build proteins. These building blocks are so critical that your body has evolved to produce many of them automatically, without any conscious effort.

Quick Summary

The human body manufactures 11 of the 20 standard amino acids crucial for health. These are known as nonessential amino acids. The remaining nine, called essential amino acids, must be obtained through your diet.

Key Points

11 Nonessential Amino Acids: Your body automatically synthesizes 11 of the 20 amino acids it requires for protein production.
Nine Essential Amino Acids: The remaining nine essential amino acids cannot be made by the body and must be obtained from dietary sources.
Categorical Importance: The terms 'essential' and 'nonessential' refer to dietary necessity, not biological function, as all 20 amino acids are vital.
Conditionally Essential Amino Acids: During illness, stress, or rapid growth, some nonessential amino acids may become conditionally essential due to increased demand.
Metabolic Synthesis: Your body manufactures nonessential amino acids using complex metabolic pathways, drawing from intermediates of glycolysis and the Krebs cycle.
Dietary Balance: Consuming a variety of protein sources, both complete and incomplete, is the best way to ensure you get all the amino acids your body needs.

The 11 Nonessential Amino Acids Your Body Synthesizes

Your body can synthesize 11 of the 20 standard amino acids. This process is automatic and doesn't require conscious thought. These are termed 'nonessential' because your body produces them internally, meaning they aren't essential components of your diet. The synthesis occurs through metabolic pathways utilizing intermediates from core processes like glycolysis and the Krebs cycle.

The 11 nonessential amino acids include Alanine, Arginine, Asparagine, Aspartic Acid, Cysteine, Glutamic Acid, Glutamine, Glycine, Proline, Serine, and Tyrosine.

The Nine Essential Amino Acids from Your Diet

The nine essential amino acids cannot be produced by your body and must come from your diet. These are vital for growth, repair, immune function, and metabolism. Ensuring a balanced diet with various protein sources guarantees you get all nine.

The nine essential amino acids are Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine. Each plays distinct roles, from producing neurotransmitters to forming structural proteins.

The Role of Conditionally Essential Amino Acids

Certain nonessential amino acids can become 'conditionally essential' under specific conditions like stress, illness, or rapid growth. In these situations, the body's production might not be enough, requiring dietary intake. Conditionally essential amino acids often include arginine, cysteine, glutamine, glycine, proline, serine, and tyrosine.

Understanding the Synthesis Pathways

The body's ability to create nonessential amino acids involves intricate metabolic pathways. These pathways often use intermediates from carbohydrate and fat metabolism. For example, alpha-ketoglutarate from the Krebs cycle is a precursor for several amino acids. This complex process ensures the availability of building blocks without conscious effort. You can find more information on these processes on the NCBI website.

Essential vs. Nonessential Amino Acids: A Comparison


Feature	Essential Amino Acids	Nonessential Amino Acids
Source	Must be obtained from the diet through protein-rich foods.	Produced by the body from other molecules and amino acids.
Number	There are nine essential amino acids.	There are 11 standard nonessential amino acids.
Dietary Requirement	Required for all individuals to consume in their daily diet.	Not strictly required in the diet, though intake is still beneficial.
Body's Production	The human body cannot synthesize them.	The human body can synthesize them continuously.
Examples	Leucine, Lysine, Tryptophan.	Alanine, Glycine, Serine.
Risk of Deficiency	High risk of deficiency if dietary intake is insufficient.	Very low risk of deficiency in healthy individuals.

Conclusion

Your body efficiently makes 11 of the 20 necessary amino acids automatically. This highlights the importance of dietary intake for the nine essential amino acids it cannot produce. Understanding this distinction is key to a balanced diet rich in complete protein sources, which supports the body's complex biological functions. While internal synthesis handles some, external nutrients are vital for overall health.

Frequently Asked Questions

The 11 nonessential amino acids your body makes are alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.

Amino acids are called 'essential' because your body cannot synthesize them on its own. They are an essential part of your diet and must be consumed through protein-rich foods.

No, nonessential amino acids are not less important. The 'nonessential' label refers to the fact that your body can produce them, not their importance. All 20 amino acids are crucial for human health.

A conditionally essential amino acid is one that is normally nonessential, but becomes essential under specific circumstances, such as stress, illness, or rapid growth, when the body's synthesis cannot keep up with demand.

Your body uses metabolic pathways to synthesize nonessential amino acids from other compounds. For example, glutamic acid is made from alpha-ketoglutarate, an intermediate in the Krebs cycle.

The essential amino acids that your body cannot make are obtained from your diet. Complete protein sources like meat, eggs, and soy contain all nine essential amino acids.

Vegetarians and vegans can get all essential amino acids by eating a combination of different incomplete protein sources throughout the day, such as combining grains, legumes, nuts, and seeds.