L-Tyrosine
Amino acid precursor with no direct AGA evidence.
How L-Tyrosine works — and how well we know it
Amino acid precursor to thyroid hormone synthesis. Marketed connection to hair is indirect through thyroid (and thyroid hormones do affect hair cycling — but not by way of dietary tyrosine).
oral
Variable.
Dietary amino acid supplement. Precursor to thyroid hormones, catecholamines, and melanin.
Nothing AGA-specific.
Evidence distribution across 1 claims
Why the grade is F. No AGA evidence; the thyroid-precursor link to hair is several inferential steps away.
Every claim, traced back to its source
We took every major claim made about L-Tyrosine and matched it to the specific experimental model behind it. Click a claim to see the model, the finding, and our assessment of how much weight it deserves.
1 claims · evidence-by-evidence breakdown
1Open-LabelWeight: LowNo AGA evidenceNo evidence.
Absence of evidence.
No AGA trials of L-tyrosine.
Inclusion is precursor logic without clinical support.
What's still missing from the science
- Any.
Our verdict on L-Tyrosine
Not in our formulary yet
We don't carry this ingredient. We only formulate around actives where the evidence — and the safety profile — is strong enough to recommend with confidence. As the data matures, we may revisit.
Related treatments
How does L-Tyrosine stack up against its closest peers?
A genuine cause of reversible hair shedding in iron-deficient patients — but useless and potentially harmful if your iron stores are normal.
Read the breakdown →A botanical 5-alpha reductase inhibitor whose only high-quality trials (in BPH) showed no benefit over placebo; the positive AGA data are small and low-quality.
Read the breakdown →One small Malaysian RCT showed a hair-count increase. Never replicated. Used by Nutrafol to justify its tocotrienol content.
Read the breakdown →