Essential Amino Acids

Amino Acids You Must Add To Your Diet

Histidine molecule
PASIEKA / Getty Images

This is an explanation of what essential amino acids are and a list of the essential amino acids for humans.

What Is an Essential Amino Acid?

An essential amino acid may also be called an indispensable amino acid. This is an amino acid that the body cannot synthesize on its own, so it must be obtained from the diet. Because each has its own physiology, the list of essential amino acids is different for humans than it is for other organisms.

Essential Versus Conditionally Essential Amino Acids

The essential amino acids for all people are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Several other amino acids are conditionally essential amino acids, meaning they are required at some stages or growth or by some people who cannot synthesize them, either because of genetics or a medical condition.

In addition to the essential amino acids, babies and growing children also need arginine, cysteine, and tyrosine. Individuals with phenylketonuria (PKU) need tyrosine and also must limit their intake of phenylalanine. Certain populations need arginine, cysteine, glycine, glutamine, histidine, proline, serine and tyrosine because they either cannot synthesize them at all or else are unable to make enough to meet the needs of their metabolism.

Learn More About Amino Acids

Amino Acid Facts
Amino Acid Structures
Amino Acid Chirality
Tryptophan Facts

List of Essential Amino Acids

Essential Amino AcidsNon-Essential Amino Acids
histidinealanine
isoleucinearginine*
leucineaspartic acid
lysinecysteine*
methionineglutamic acid
phenylalanineglutamine*
threonineglycine*
tryptophanproline*
valineserine*
 tyrosine*
 asparagine*
 selenocysteine
 *conditionally essential
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Helmenstine, Anne Marie, Ph.D. "Essential Amino Acids." ThoughtCo, Feb. 13, 2017, thoughtco.com/what-are-the-essential-amino-acids-608193. Helmenstine, Anne Marie, Ph.D. (2017, February 13). Essential Amino Acids. Retrieved from https://www.thoughtco.com/what-are-the-essential-amino-acids-608193 Helmenstine, Anne Marie, Ph.D. "Essential Amino Acids." ThoughtCo. https://www.thoughtco.com/what-are-the-essential-amino-acids-608193 (accessed November 19, 2017).