What do the states mean?+
- Solid: well studied, and it works.
- Half-there: the science is still forming.
- A ghost: almost no real studies.
- Hollow: well studied, and it does not work.
- A cord: the pair itself has been tested together.
- Air: nobody has ever tested this pair.
The full scoring method: How we score
L-tyrosine benefits: where the science stands
For memory and focus: not settled yet.
Memory and focus are what most people take L-tyrosine for, and the best studies disagree: four found it helps, four found no effect. As of August 2026, the verdicts on this page rest on evidence from 36 trials, drawn from the strongest research among the 1,850 papers on PubMed that mention L-tyrosine. Every claim is checked below.
1,850 papers on PubMed · evidence from 36 trials · 1 caution
Claim by claim
- Memory and focusThe science is still forming. The best studies disagree.
- Cold toleranceAlmost no real studies. What exists leans positive.
- EnduranceWell studied, and it does not work. The biggest review covered 8 trials.
- Energy and fatigueAlmost no real studies. Nothing clear so far.
See 2 more scored claims+
- SleepAlmost no real studies. Nothing clear so far.
- Stress and anxietyThe science is still forming. No real difference found so far.
Pairs people ask about
The 15 sources we read
- 1989Randomized trial · 10 people · no clear effect on energy and fatigue; no clear effect on sleepsource
- 1995Crossover trial · 24 people · no clear effect on memory and focussource
- 1998Crossover trial · 21 people · no clear effect on memory and focussource
- 2011Crossover trial · 8 people · benefit for endurancesource
- 2014Crossover trial · benefit for memory and focussource
- 2014Crossover trial · 7 people · no clear effect on endurancesource
- 2015Meta-analysis · pools 15 trials · benefit for memory and focussource
- 2016Crossover trial · 8 people · no clear effect on endurance; no clear effect on memory and focussource
- 2017Randomized trial · 22 people · benefit for cold tolerancesource
- 2020Meta-analysis · benefit for memory and focussource
- 2020Randomized trial · 18 people · benefit for cold tolerancesource
- 2021Meta-analysis · no clear effect on memory and focussource
- 2023Meta-analysis · pools 8 trials · no clear effect on endurancesource
- 2024Randomized trial · 55 people · benefit for memory and focus; no clear effect on stress and anxietysource
- 2026Crossover trial · 12 people · moderate benefit for endurancesource
Chosen as the strongest evidence out of 1,850 papers on PubMed. Every row links to its paper.
Fair questions
Does L-tyrosine work?+
For memory and focus, it is not settled. The best studies disagree.
Is L-tyrosine safe?+
One caution is recorded: Searching 21 health outcomes returned no trial of L-tyrosine on its own for any of them. This is not the same as a supplement nobody has studied. Tyrosine is a nutrient your body needs, and there is research on it. What that research is about is an amino acid measured inside other studies, plus a large oncology literature on tyrosine kinase inhibitors, which are drugs and not this supplement. None of it tells you whether taking extra helps someone who already gets enough.
Why only 15 sources, when PubMed lists 1,850?+
The 1,850 is every paper that mentions L-tyrosine in any way: animal studies, blood measurements, papers where it is a side note. The strongest sources are combined reviews, and each one already gathers every trial its authors could find. Our 15 cover 36 trials between them, and every one is linked above. Both counts are measured, not estimated.