L-Carnitine for Fatigue
L-carnitine is not a reliable remedy for everyday fatigue. The strongest evidence shows no benefit for cancer-related fatigue, and the few positive trials are limited to specific older or disease-affected groups who may have been carnitine-deficient.
Why this grade7-layer evidence engine
This earns a Weak (C) grade because the evidence is mixed and highly population-dependent rather than supportive of broad use. The largest and highest-quality trial, a 376-patient double-blind RCT (PMID 22987089), found no benefit over placebo for cancer-related fatigue, and a systematic review and meta-analysis (PMID 29112178) agreed, reporting a negligible effect (SMD 0.06; p=0.45). These are the most rigorous data available, and they are null.
Positive results exist only in narrow groups: centenarians (PMID 18065594), elderly patients (PMID 17658628), prefrail older adults (PMID 27895474), and people with hepatic encephalopathy (PMID 21310833). These trials were small, often did not disclose funding, and used populations prone to carnitine deficiency, so the improvement likely reflects correcting a deficit rather than a general anti-fatigue effect. The hepatic encephalopathy benefit may also be confounded by falling ammonia levels.
Regulators and clinicians reinforce caution. The US FDA treats L-carnitine only as a nutrient supplement, the EU's EFSA has rejected related health claims, and the Mayo Clinic states it is not recommended for MS-related fatigue. No authority endorses it for fatigue, and for cancer-related fatigue guideline bodies favor exercise as first-line care. Adequately powered trials in healthy adults are essentially absent.
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 = 0.448
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高階證據未達主導 (0 positive vs 1 negative)，由 raw_score 決定
- 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