L-Tyrosine for Stress
L-tyrosine earns a weak evidence grade: it may briefly protect memory and mental performance during intense acute stressors like cold or military training, but there is no evidence it relieves everyday or chronic stress, anxiety, or low mood.
Why this grade7-layer evidence engine
The grade stays weak because the human evidence is small and confined to short-term physical stress. Two 2015 systematic reviews gave only a weak recommendation for tyrosine and found a benefit to cognition merely when acute stress has temporarily depleted dopamine and noradrenaline, with no pooled effect size (PMID 26126245; PMID 26424423). The supporting trials are tiny double-blind RCTs in cold-water immersion (PMID 17585971, n=19) and combat-training cadets (PMID 10230711, n=21), almost all government- or military-funded, which limits how far the results carry to ordinary life.
Regulators back only the underlying biology, not a stress claim. The US FDA lists L-tyrosine as a GRAS nutrient supplement with no approved health claim, and the EU EFSA confirmed it supports normal catecholamine and dopamine synthesis but explicitly rejected an 'increased attention' functional claim. The UK NHS makes no recommendation, citing insufficient efficacy and safety data. Among major clinics, only Cleveland Clinic comments, saying it may ease memory loss under stress while calling the evidence limited; Mayo Clinic and Harvard Health do not address it.
For everyday use the takeaway is narrow: tyrosine is not a general de-stress or anti-anxiety supplement, and the studied doses and settings (acute cold, noise, military operations) do not mirror normal stress. A drug-interaction caution also applies, including a hypertensive risk if combined with MAO inhibitors. Approaches with far stronger support, such as regular exercise, cognitive behavioral therapy, and mindfulness-based stress reduction, remain the better-evidenced choices for managing stress.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.522
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (1 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status