GABA (gamma-Aminobutyric Acid) for Anxiety
Early human trials suggest oral GABA may modestly ease anxiety, but the evidence is limited and low-quality, so it should not be treated as a proven anxiety treatment. No regulator or major clinic endorses it for this use.
Why this grade7-layer evidence engine
This earns a preliminary (Tier B) grade because the supporting human data is thin and mixed. A 2020 systematic review (PMID 33041752, 14 studies) found only limited, heterogeneous signals for stress and anxiety—some EEG alpha-wave and autonomic changes—but the trials were too small and varied to pool into a meta-analysis.
Two small randomized trials hint at benefit: a 2025 open-label RCT in 168 surgical patients (PMID 40026748) reported effective pre-operative anxiety relief with little sedation, and a 2024 double-blind RCT in 30 women (PMID 38321713) showed improved DASS-21 anxiety and mood scores over 13 weeks. Both are small, short, and one is unblinded, so they raise the grade only modestly.
Caution is warranted: it is disputed whether oral GABA even crosses the blood-brain barrier, and several key studies have undisclosed or industry-linked funding. The US FDA lists GABA only as a flavoring agent, not an approved food ingredient, and no major health authority or clinic endorses it for anxiety—so it remains a possible aid, not a substitute for established care.
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 = 0.58
- 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