Hyaluronic Acid (Sodium Hyaluronate) for Osteoarthritis
For knee osteoarthritis, oral hyaluronic acid supplements have only weak, low-quality evidence: several small trials report modest relief of pain and stiffness, but the studies are tiny, mostly test combination products, and are largely industry-funded. This is entirely separate from hyaluronic acid joint injections, which have a much larger evidence base.
Why this grade7-layer evidence engine
The grade reflects a body of small, short trials that lean positive but are not convincing on their own. Two systematic reviews were broadly favorable: a 2024 review (PMID 39886281, 597 participants) found 9 of 11 studies reported improvements in pain and function, and an earlier review (PMID 26818459) reported consistent knee-pain relief — but the latter was a non-independent paper from a manufacturer's R&D staff and was rated low quality.
The underlying randomized trials are weak. The only year-long study (PMID 23226979, n=60) missed its overall endpoint and reached significance only in a subgroup aged 70 or under. Shorter trials reporting WOMAC and pain benefits were tiny and tested combinations — HA plus glucosamine and chondroitin (PMID 33592868, n=47), or HA with krill oil and astaxanthin (PMID 37686801, n=75) — so hyaluronic acid's own effect cannot be isolated. A 12-week sodium-hyaluronate trial (PMID 38234616) had only 31 participants. Most were industry-funded, triggering a conflict-of-interest flag.
Regulators and major clinics have not endorsed oral use. The US FDA stopped its safety (GRAS) evaluation of oral sodium hyaluronate ("At the notifier's request, FDA ceased to evaluate this notice"), EFSA rejected joint-health claims, and the NHS and WHO do not address it. The Mayo Clinic comments only on HA injections — noting some research finds them no better than placebo — underscoring that the relatively stronger injection evidence should not be read as support for oral supplements.
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 = 0.576
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (2 篇 > 0 negative)
- tier_strict_requirement_check — | B→C 因 scope.conflation_risk=true 且 L11 獨評較低 (B7-2 tier cap)
- detect_disputes — 偵測到 0 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status