Synopsis

Source of validity: Scientific
Rating (out of 5): 2

L-tryptophan is an essential amino acid that serves as a precursor to serotonin, a neurotransmitter associated with mood regulation, anxiety, and sleep. Scientific interest in L-tryptophan for nervousness (a symptom often related to anxiety or stress) stems from its role in serotonin biosynthesis. Some clinical studies have found that L-tryptophan supplementation can influence mood and may have anxiolytic (anxiety-reducing) effects, likely due to increased serotonin production in the brain. For example, research indicates that low tryptophan intake or depletion can worsen mood and increase anxiety in susceptible individuals, while supplementation may have modest benefits for mood stabilization and reduction of nervousness.

However, the overall quality and quantity of direct evidence specifically assessing L-tryptophan for nervousness is limited. Most studies are small or involve related conditions such as mild depression or generalized anxiety. Systematic reviews often note the need for larger, well-controlled trials to confirm its efficacy and safety. Adverse events, particularly the historical association with eosinophilia-myalgia syndrome in contaminated supplements, have also tempered enthusiasm for widespread use.

In summary, while there is a plausible biological mechanism and some early clinical support for using L-tryptophan to address nervousness, the scientific evidence is modest and not definitive. It may offer benefit for some individuals, but it should be used with caution and not as a first-line treatment for nervousness or anxiety.

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Nature's Sunshine Free Amino Acids