How does L-tyrosine affect dopamine?

L-tyrosine is an amino acid precursor to L-DOPA and further down the pathway, to dopamine. Supplementation with L-tyrosine can increase levels of dopamine, lead to feelings of increased energy, alertness, and focus. Typically, L-tyrosine is taken in dosages ranging from 500 to 1000 milligrams, resulting in increased dopamine levels roughly 30 to 45 minutes after ingestion, with effects peaking shortly afterward and lasting for a variable duration of time 1.

However, Andrew Huberman does warn that L-tyrosine can produce a crash, leaving individuals feeling lethargic or having brain fog after its effects wear off 2. He also notes the variance in individual sensitivity to L-tyrosine, with some people able to tolerate higher dosages and others far less, or none at all 3. Moreover, it is important to approach L-tyrosine supplementation with caution, especially for people with underlying psychiatric or mood disorders such as mania, bipolar disorder, or schizophrenia, due to the potential for it to dysregulate the dopamine system 4.