Sea Buckthorn for Dry Eye Disease
Sea buckthorn oil earns only a weak evidence grade for dry eye disease: small, industry-funded trials suggest it can modestly ease subjective symptoms such as burning and redness and blunt the seasonal rise in tear-film osmolarity, but it does not reliably improve objective signs. It is an optional adjunct at best and is no substitute for artificial tears or prescription therapy.
Why this grade7-layer evidence engine
The grade is held down by a thin, lopsided evidence base. Every human dry-eye finding traces back to a single Finnish research group (PMID 20554904): a double-blind RCT of 86 people taking 2 g/day for 13 weeks, a secondary analysis of the same cohort, a small omega-7 pilot (n=40), and a pooled review of about 180 participants total. Benefits were consistent on patient-reported symptoms (burning, redness, OSDI) and on tear-film osmolarity, but objective measures such as tear break-up time and the Schirmer test showed no consistent improvement.
Two structural weaknesses cap confidence. All the primary trials were funded by sea buckthorn producers, triggering a high-conflict-of-interest flag, and there is little independent replication, no data beyond 12 months, and no hard quality-of-life endpoints. The samples are also too small to detect rare harms, and commercial products vary in formulation, so they may not match the doses tested.
Authorities are split but unenthusiastic. The US FDA only affirms that sea buckthorn berry products are safe (GRAS), making no efficacy claim, while EFSA went further and rejected dry-eye and tear-film health claims because cause-and-effect was not established. Among clinical bodies, only TFOS DEWS II comments, calling the evidence cautious: it acknowledges the osmolarity and symptom signal from the RCT but stresses that objective signs were unchanged and further confirmation is required. Mayo Clinic, Cleveland Clinic, Harvard Health, and the NIH Office of Dietary Supplements do not address it at all.
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 = 0.393
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 無高階證據可裁決
- tier_strict_requirement_check — D 級條件未達 (需 E1-E3 negative；實際 E6)
- detect_disputes — 偵測到 0 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status