Glycine for Joint Health
There is no human clinical evidence that glycine supplements improve joint health or osteoarthritis. The case rests entirely on laboratory and animal mechanisms, so glycine cannot currently be recommended for joints.
Why this grade7-layer evidence engine
This claim is graded Unverified (Insufficient Evidence) because no randomized human trials of oral glycine for joint pain or osteoarthritis exist as of 2026. The supporting science is entirely preclinical: in cultured bovine cartilage cells, raising glycine boosted type II collagen synthesis by 60-75% (PMID 30006659), and a follow-up showed glycine was the most rate-limiting of three amino acids for collagen production (PMID 37598999). A 2025 mouse study linked a glycine-processing enzyme pathway to osteoarthritis pain, but tested a genetic knockout rather than glycine supplementation (PMID 40288509).
The mechanism is plausible, since glycine makes up roughly a third of collagen, but plausibility is not proof. A frequently cited 'glycine' benefit actually comes from collagen-peptide trials, which deliver glycine alongside proline, hydroxyproline and many other amino acids, so the effect cannot be attributed to glycine alone. One animal study often surfaced in searches used Glycine soja (wild soybean plant), not the amino acid, and is unrelated (PMID 36902256).
Authorities offer no functional support. EFSA concluded that 'a cause and effect relationship has not been established,' and the FDA addresses glycine only as a food-additive ingredient, not as a joint treatment. The NIH Office of Dietary Supplements, Mayo Clinic, Cleveland Clinic, and the American College of Rheumatology and AAOS guidelines do not mention glycine for joints; rheumatology guidance instead names omega-3, vitamin D and turmeric.
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 = 0.453
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 僅有 E10 級證據 (cohort/animal/mechanism)，不足以下結論
- tier_strict_requirement_check — C 級條件未達 (需 E1-E8；實際 E10 僅機轉)
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status