Essential amino acids are
amino acids that the human body cannot produce in sufficient amounts and therefore must be obtained from the diet.
Adult humans have 9 essential amino acids:
- Histidine
- Isoleucine
- Leucine
- Lysine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
There are also some additional
conditionally essential amino acids.
The term "essential" does not mean the amino acid is more important than a
nonessential amino acid. It means the body cannot synthesize enough of it to meet its needs, so dietary intake is necessary.