Astaxanthin for Skin Health
Oral astaxanthin shows a modest signal for improved skin elasticity and moisture in small trials, but the evidence base is weak, heavily funded by the astaxanthin industry, and no regulator or clinic endorses it for skin health. Treat any skin benefit as unproven rather than established.
Why this grade7-layer evidence engine
The strongest support comes from a 2021 systematic review and meta-analysis (PMID 34578794, n=327), which found statistically significant gains in skin elasticity (SMD 0.77) and moisture (SMD 0.53) but no effect on wrinkle depth. Even there, the elasticity result was highly inconsistent across studies (I-squared 75%), and the review's own authors warned that positive findings may reflect commercial influence.
The underlying randomized trials are tiny and narrow: a 2018 UV-exposure RCT (PMID 29941810, n=23) and a 2012 cosmetic RCT (PMID 22428137, n=36) reported improvements in sun-resistance and crow's-feet, but both were run by FUJIFILM or Fuji Chemical staff, a serious conflict of interest, and measured only short-term surrogate skin markers rather than meaningful outcomes.
Crucially, an independent 2025 meta-analysis of photoaging supplements (PMID 40761858) concluded the evidence is insufficient to recommend astaxanthin, favoring collagen and polyphenols instead. No authority backs an efficacy claim: the EU EFSA non-authorized all astaxanthin health claims, the US FDA lists it only as a salmon-feed color additive, and Mayo, Cleveland, Harvard and NIH offer no endorsement. Hence a weak C grade, published with a warning.
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 = 0.542
- 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 — 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