L-lysine,
does it really help with Relief of stress and anxiety?
research showsThe closest evidence for L-lysine alone is a fortified-food trial in a Syrian community with low lysine intake, with positive findings limited to selected sex-specific outcomes. The 108-person and 29-person trials both used lysine plus arginine, so their effects cannot be attributed to L-lysine alone. Deficiency correction, combination ingredients, and manufacturer concentration support C with 44 points.
ads claimMarketing states that one amino acid regulates serotonin receptors and cortisol to reduce ordinary stress. Human evidence centers on deficiency correction and a lysine-arginine combination, which is not equivalent to a single-ingredient L-lysine product.
Useful facts when choosing a product
- The Syrian study used lysine-fortified flour, not a supplement capsule.
- The Japanese trial combined lysine 2.64 g/day with arginine 2.64 g/day.
- Main outcomes were short-term measures such as anxiety questionnaires, salivary cortisol, and skin conductance.
- Key human studies had funding or author links to Ajinomoto.
Chamgap Semantic Classification Code
Candidate index · review held
UNK.l-lysine.UNK.stress-and-anxiety.relieve.placeboUnknown > L-lysine > Unknown > stress and anxiety > Symptom-relief claim > Placebo
An automated migration candidate, not an issued permanent code; exact claim scope remains under review. This machine-generated migration candidate helps retrieval but is not a permanent assignment. The original verdict ID and URL remain authoritative.
What the research actually shows
The Smriga 2004 study provided lysine-fortified flour for three months in a low-intake Syrian community and found improvements in selected sex-specific outcomes, including trait anxiety in men, the cortisol response to blood drawing in women, and skin conductance in men. This is the closest evidence for L-lysine alone, but it is a deficiency-correction food-fortification study. The 108-person Smriga 2007 and 29-person Jezova 2005 trials both used lysine plus arginine, so they cannot establish efficacy of L-lysine alone.
Why this is classified as C (44)
Signals in two randomized human studies mean the evidence is not ungradable, but a deficiency-risk population, combination ingredients, sex-specific results, short-term surrogates, and manufacturer concentration limit it to C with 44 points.
Counterpoint. A nutritional-correction effect remains possible in diets with low lysine intake, which is distinct from additional supplementation in people with adequate intake.
Rejudgment record. Reassessment (cross-check reflected) — Randomized human signals exist, but they involve a lysine-deficiency-risk population or lysine-arginine combinations, sex-specific outcomes, short-term surrogates, and concentration of evidence around Ajinomoto
Cross-check — AI research and Codex final gate
Evidence Table
| Study | Design | Sample | Funding | Endpoint | Result | Weight |
|---|---|---|---|---|---|---|
| Smriga M et al. 2004 | Three-month randomized double-blind food-fortification trial | Ajinomoto Co., Inc. | Trait anxiety, cortisol response, and skin conductance | Selected sex-specific outcomes improved, but this was a fortified-food study in a population with low lysine intake. | Key | |
| Smriga M et al. 2007 | Randomized double-blind placebo-controlled trial | 108 | Authors affiliated with Ajinomoto | Trait and state anxiety, salivary cortisol, and chromogranin A | The lysine-arginine combination reduced anxiety scores and selected basal hormonal markers in men. | Key |
| Smriga M et al. 2005 | Randomized double-blind placebo-controlled stress-challenge trial | 29 | Ajinomoto-linked | Hormonal, cardiovascular, and skin-conductance responses to public-speaking stress | The lysine-arginine combination altered hormonal and skin-conductance responses, while heart rate and blood pressure did not differ. | Supportive |
Receipt — 3 References
All 3 cited sources were verified for existence at the original page (as of 2026-07-11).
Final verification and publication gate: Codex · Evidence date: 2026-07-11 · Corrections: none
Cite this verdict
[Chamgap] L-lysine x Relief of stress and anxiety — Evidence Grade C·44. 3 cited sources checked. Source: https://chamgap.com/en/verdicts/mood/l-lysine-stress-anxiety/ · CC BY 4.0CC BY 4.0 — free to use with attribution; do not distort grades, numbers, or verdict meaning.
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