Evidence supporting the use of: L-tyrosine
For the body system: Specific Neurotransmitters

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Synopsis

Source of validity: Scientific
Rating (out of 5): 3

L-tyrosine is an amino acid that serves as a precursor for the synthesis of several important neurotransmitters in the body, including dopamine, norepinephrine, and epinephrine. Its use to support the "Specific Neurotransmitters" body system is primarily justified by scientific evidence, although the strength of this evidence is moderate.

Studies have shown that L-tyrosine supplementation can influence neurotransmitter levels, particularly under conditions of acute stress, sleep deprivation, or cognitive demand. Research in both animals and humans suggests that L-tyrosine may help maintain cognitive performance and working memory when neurotransmitter stores are likely to be depleted, such as during prolonged stress or exhaustive exercise. For example, a review published in Military Medicine (2007) concluded that L-tyrosine might improve cognitive performance in stressful situations.1

However, for the general population and in the absence of significant stressors, there is limited evidence that L-tyrosine supplementation substantially boosts neurotransmitter function or mental performance. The effects appear to be context-dependent rather than universally applicable. Nevertheless, its biochemical role as a direct precursor for catecholaminergic neurotransmitters supports its rationale for use in formulas targeting neurotransmitter support.

1. Deijen JB, et al. Tyrosine supplementation and its effect on neurotransmitter function in stress. Military Medicine. 2007;172(11 Suppl):S51-4.

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