L-is an – one of the twenty genome-encoded building blocks from which proteins are constructed. It is used to produce the neurotransmitters and dopamine, and appears to protect against acute stress (which tends to deplete ).
High stress can exacerbate age-related decline of the immune system, promoting inflammation and increasing the risk of chronic diseases of ageing. such as can exert a protective effect during stressful situations. Production of these molecules is highly regulated, and so taking L- won’t necessarily increase levels. However, it may provide a ‘safety buffer’ of building blocks that can make the anti-stress effect of last longer by slowing their depletion.
A meta analysis of 10 randomised and 4 non-randomised made a weak recommendation in favour of tyrosine, as all studies
showed a positive effect for mitigation of cognitive stress. Tyrosine reduced the impact of stressors such as sleep deprivation, noise, extreme climates and military training on various cognitive processes including memory, and reasoning. Studies outside of this analysis have also suggested that tyrosine can reduce perceived stress during acute stressors.
Overall, tyrosine shows promise as a supplement for stress reduction and cognitive enhancement during acute stressors, and deserves further research so that a more confident conclusion can be made.
Examine.com: L-Tyrosine: https://examine.com/supplements/l-tyrosine/
Tyrosine for Mitigating Stress and Enhancing Performance in Healthy Adult Humans, a Rapid Evidence Assessment of the Literature: DOI: 10.7205/MILMED-D-14-00594
A Systematic Review of the Effect of Dietary Supplements on Cognitive Performance in Healthy Young Adults and Military Personnel: https://doi.org/10.3390/nu12020545
Treatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humans: DOI: 10.1016/0361-9230(89)90096-8