Nonessential amino acid
Tyrosine
Limited evidenceA building block for dopamine and norepinephrine, studied under acute stress.
What it is
The body makes tyrosine from phenylalanine. It is a precursor to dopamine, norepinephrine, and thyroid hormones.
Food sources
CheeseChicken and turkeySoyFishNuts and seeds
What the research shows
- Small studies suggest it may help maintain mental performance under acute stress, such as cold or sleep loss.
- Benefits in normal, unstressed conditions are not well supported.
Read the published research on PubMed →
Food first: most people get what they need from a varied diet with enough total protein. Talk to a provider or registered dietitian before adding a supplement, especially if you take medication or have a health condition.
Similar evidence level
Conditionally essential amino acid
Arginine
A precursor to nitric oxide, though oral supplements are poorly absorbed for that purpose.
Limited evidenceConditionally essential amino acidGlutamine
The most abundant amino acid in the blood, often oversold for muscle recovery.
Limited evidenceNonessential amino acidGlycine
The simplest amino acid, a major part of collagen, and studied for sleep.
Limited evidence