Systematic Review and Meta-Analysis on the Effects of Astaxanthin on Human Skin Ageing

Abstract

Context: Astaxanthin (ASX), a xanthophyll carotenoid derived from microalgae Haematococcus pluvialis, mitigating skin photoaging and age-related skin diseases by its antioxidant and anti-inflammatory effects in animal studies.

Objective: The aim was to systematically evaluate if ASX applications have anti-ageing effects in humans.

Methods: A comprehensive search of PubMed, Scopus and Web of Science found a total of eleven studies. Nine randomised, controlled human studies assessed oral ASX effects and two open-label, prospective studies evaluated topical, oral-topical ASX effects on skin ageing. GetData Graph Digitizer was used to extract mean values and standard deviations of baseline and endpoint, and Cochrane Collaboration's tool assessed RoB for all included studies. Review Manager 5.4 was used to conduct meta-analysis of RCTs; the results were reported as effect size ± 95% confidence interval.

Results: Oral ASX supplementation significantly restored moisture content (SMD = 0.53; 95% CI = 0.05, 1.01; I² = 52%; p = 0.03) and improved elasticity (SMD = 0.77; 95% CI = 0.19, 1.35; I² = 75%; p = 0.009) but did not significantly decrease wrinkle depth (SMD = -0.26; 95% CI = -0.58, 0.06; I² = 0%; p = 0.11) compared to placebo. Open-label, prospective studies suggested slightly protective effects of topical and oral-topical ASX applications on skin ageing.

Conclusions: Ingestion and/or topical usages of ASX may be effective in reducing skin ageing and have promising cosmetical potential, as it improves moisture content and elasticity and reduces wrinkles.

Keywords: anti-inflammation; antioxidant; astaxanthin; skin ageing.

Figure 1

The mechanisms that UV-rays promote skin photoaging (created with BioRender.com. https://app.biorender.com/illustrations/61123dbdedaefd00a5e711d7. Accessed on 12 August 2021).

Figure 2

Chemical structure of ASX (A) and β-carotene (B) (created with KingDraw http://www.kingdraw.cn/en/index.html , accessed on 2 February 2021).

Figure 3

PRISMA flow diagram summarized identified studies during the literature review.

Figure 4

Forest plots summarizing the impact of ASX oral supplementation on (A) the increase in moisture content (µS), and (B) the increase in skin elasticity (%) using a random-effects model, as well as (C) the reduction in wrinkle depth (µm) using a fixed-effects model. Pooled summary data are presented as mean differences compared to control. The area of each green symbol is proportional to the weight of the study. Squares represent the standard mean differences, bars represent the 95% CI, and diamonds show the pooled effect.

Figure 5

(A) Graph of RoB for each study according to the seven domains defined by Cochrane Collation’s tool. (B) Review of each RoB item presented as percentages across all included studies according to the judgments of the author.