Astaxanthin for Eye Health & Vision

Eye Health — scientific infographic poster

Astaxanthin is studied for the eye because of its light-related antioxidant chemistry; the human trials so far are small and short. In 60 healthy adults, 9 mg/day for 6 weeks preserved corrected visual acuity after screen work in those aged 40 and over but not in younger participants (Sekikawa 2023). In early age-related macular degeneration, the CARMIS trials gave astaxanthin 4 mg/day inside a seven-ingredient combination, so its own contribution cannot be separated (Parisi 2008; Piermarocchi 2012). In cataract patients, 6 mg/day for 2 weeks raised antioxidant activity in the fluid at the front of the eye (Hashimoto 2013). The widely repeated "6,000 times vitamin C" figure comes from one solvent-based laboratory assay, not from studies in people.

Table of Contents

  1. The Blood-Retinal Barrier: What Is Known About Astaxanthin Reaching the Eye
  2. Singlet Oxygen and the Photoreceptor
  3. Asthenopia (Eye Strain) and Screen Work
  4. The CARMIS Macular Degeneration Trials (Parisi 2008, Piermarocchi 2012)
  5. Blue Light and Screen Exposure: What Has Been Studied
  6. Diabetic Retinopathy: Laboratory and Animal Data
  7. Dry Eye: Uncontrolled and Combination Studies
  8. Choroidal Blood Flow and Glaucoma Research
  9. Lutein, Zeaxanthin and Astaxanthin in Combination Trials
  10. Doses Used in Eye Studies and Intake Limits
  11. Safety Findings Relevant to Eye Research
  12. Key Research Papers
  13. Connections
  14. Featured Videos

The Blood-Retinal Barrier: What Is Known About Astaxanthin Reaching the Eye

The blood-retinal barrier is the eye's counterpart of the blood-brain barrier — a tight-junction structure formed by the retinal capillary endothelium (the inner barrier) and the retinal pigment epithelium (the outer barrier) that controls what reaches retinal tissue. It protects the retina from circulating pathogens, toxins and inflammatory mediators, and it also limits which nutrients get in.

The macula concentrates two dietary carotenoids, lutein and zeaxanthin, which form the macular pigment. Whether, and how much, astaxanthin reaches the human retina after oral intake has not been measured in people. The human measurement available is from the front of the eye: in 35 patients having cataract surgery on both eyes, the second eye was operated on after 6 mg/day astaxanthin for 2 weeks, and the fluid taken from the front of the eye (aqueous humor) then showed higher superoxide-scavenging activity and lower total hydroperoxides (Hashimoto 2013). That measured the aqueous humor, not the retina. Brain uptake has been shown in rats, not people (Manabe 2018).

Claims that astaxanthin is "the only carotenoid" that crosses both the blood-retinal and blood-brain barriers, or that it distributes throughout the whole human retina at a stated dose, were not supported by any study found for this page. For the broader retinal disease context, see Macular Degeneration and the Ophthalmology landing page.

Back to Table of Contents

Singlet Oxygen and the Photoreceptor

The retina is exposed to focused light, has a very high oxygen consumption, and its photoreceptor outer segments are rich in polyunsaturated fatty acids, especially DHA, which are vulnerable to oxidation. Light energy transferred to oxygen by light-absorbing molecules produces singlet oxygen (¹O&sub2;), an excited, highly reactive form of oxygen. The enzymes superoxide dismutase and catalase act on superoxide and hydrogen peroxide, not on singlet oxygen; carotenoids deactivate ("quench") it mainly by absorbing its excess energy.

The widely repeated "6,000 times vitamin C" figure traces to a 2007 chemiluminescence assay that measured how fast each compound quenched singlet oxygen in a laboratory solvent mixture. A 2023 review led by the same first author tabulates that assay's rate constants, in units of 10⁹ per molar per second (Nishida 2023):

An earlier comparison of marine carotenoids by Shimidzu, Goto and Miki (1996) is also commonly cited. In other assays listed in the 2023 review, the gap between astaxanthin and beta-carotene ranged from none to large, and in phospholipid membrane models astaxanthin sometimes showed a lower rate than beta-carotene. These numbers are reaction speeds in a test tube; they do not show how much astaxanthin reaches the eye or whether vision changes. Other multiples often quoted (550 times vitamin E, 11 times beta-carotene, 800 times CoQ10, 5 times lutein) were not supported by the sources found for this page.

Back to Table of Contents

Asthenopia (Eye Strain) and Screen Work

Asthenopia is the medical term for eye strain — tired eyes, blurred vision, headache, dryness and difficulty focusing after prolonged close work, especially screen use. Proposed contributors include fatigue of the ciliary muscle that focuses the lens, a lower blink rate, and oxidative stress.

Randomized trials indexed in PubMed:

Earlier Japanese accommodation trials (Nagaki 2002, Iwasaki 2006, Nakamura 2004) are often cited for eye strain. They appeared in Japanese-language journals that are not indexed in PubMed, and their methods and results could not be checked for this page, so their reported doses and findings are not repeated here.

Back to Table of Contents

The CARMIS Macular Degeneration Trials (Parisi 2008, Piermarocchi 2012)

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss in older adults. The AREDS and AREDS2 trials tested antioxidant-plus-zinc combinations in AMD; astaxanthin was not part of either formula. The Italian CARMIS study tested a combination that included it.

Parisi 2008 (12 months). 27 patients with non-advanced AMD were randomized to a daily combination of vitamin C 180 mg, vitamin E 30 mg, zinc 22.5 mg, copper 1 mg, lutein 10 mg, zeaxanthin 1 mg and astaxanthin 4 mg for 12 months, or no supplement. Central retinal responses on multifocal electroretinography (0–5 degrees) improved in the treated group; the more peripheral areas did not change.

Piermarocchi 2012 (24 months). In an open-label randomized study of 145 patients with AMD given the same type of combination (lutein 10 mg, zeaxanthin 1 mg, astaxanthin 4 mg plus antioxidant vitamins) or no supplement for 2 years, the treated group had better visual acuity scores at 24 months (81.4 vs 76.8), better contrast sensitivity and higher visual-function questionnaire scores. The authors called for larger and longer studies.

Because seven ingredients were given together, neither trial shows what astaxanthin itself contributed, and the control groups received no placebo.

Back to Table of Contents

Blue Light and Screen Exposure: What Has Been Studied

Blue light (roughly 400–490 nm) is the highest-energy part of the visible spectrum. It reaches the photoreceptors and retinal pigment epithelium, where laboratory studies show it can generate reactive oxygen species. LED screens and LED lighting have increased everyday exposure to it.

No human trial of astaxanthin against a measured blue-light load was found for this page; a frequently cited "Hashimoto 2018 blue-light trial" could not be located in PubMed. The Hashimoto group's published human work measured the aqueous humor of cataract patients (Hashimoto 2013). The human trial that involved screen work is the Sekikawa 2023 study described above, which measured visual acuity after a screen task, not blue-light damage.

Back to Table of Contents

Diabetic Retinopathy: Laboratory and Animal Data

Diabetic retinopathy is one of the classic microvascular complications of diabetes. Chronic high blood glucose damages retinal capillaries through several pathways, including the polyol (aldose reductase) pathway, advanced glycation end products and oxidative stress.

No human trial of astaxanthin in diabetic retinopathy was found for this page. The published evidence is laboratory and animal work: in retinal pigment epithelial cells under high-glucose or low-oxygen conditions and in diabetic rats, astaxanthin lowered VEGF expression and its upstream signals HIF1α and XBP1 (Janani 2021); and in a gerbil model of type 2 diabetes, astaxanthin given for one week lowered red-cell aldose reductase activity (Benlarbi-Ben Khedher 2019). These do not show an effect in people. Alpha lipoic acid has its own page on this site.

Back to Table of Contents

Dry Eye: Uncontrolled and Combination Studies

Dry eye disease involves deficient tear production, an unstable tear film, increased evaporation and inflammation of the eye's surface. It is common with heavy screen use, after menopause and in autoimmune conditions such as Sjögren's syndrome.

No controlled trial of astaxanthin alone, or of astaxanthin combined with krill oil or omega-3, for dry eye was found for this page.

Back to Table of Contents

Choroidal Blood Flow and Glaucoma Research

The choroid is the blood-vessel layer behind the retina that supplies oxygen and nutrients to the outer retina and photoreceptors.

Saito 2012 — 20 healthy volunteers were randomized to 12 mg/day astaxanthin or placebo for 4 weeks. Laser speckle flowgraphy showed a significant rise in macular blood-flow velocity from baseline in the astaxanthin group and no change in the placebo group; the comparison reported was within each group, and the study was small.

In glaucoma, the research is in animals: in mice lacking a glutamate transporter, a model of normal-tension glaucoma, astaxanthin reduced thinning of the retinal ganglion cell layer measured by optical coherence tomography (Tanaka-Gonome 2020). No human trial of astaxanthin with glaucoma outcomes was found for this page.

Back to Table of Contents

Lutein, Zeaxanthin and Astaxanthin in Combination Trials

The three carotenoids have been given together in eye trials, but they have not been compared head to head:

Because the combinations were tested as wholes, these trials do not show whether adding astaxanthin changes the effect of lutein and zeaxanthin.

Back to Table of Contents

Doses Used in Eye Studies and Intake Limits

There is no official recommended intake for astaxanthin. The figures below are the doses used in studies and the limits agencies have reported, not instructions.

Intake limits. In 2020 the European Food Safety Authority concluded that 8 mg/day from food supplements, added to the astaxanthin people get from fish and crustaceans, is safe for adults, using an acceptable daily intake of 0.2 mg per kg of body weight (EFSA 2020). In the United States, the FDA has not approved astaxanthin as a dietary supplement — it does not approve supplements before they are marketed — and its listings for astaxanthin are as color additives in the feed of salmonid fish (21 CFR 73.35, 73.185 and 73.355).

Back to Table of Contents

Safety Findings Relevant to Eye Research

Back to Table of Contents

Key Research Papers

  1. Sekikawa T, Kizawa Y, Li Y, et al. (2023). Effects of diet containing astaxanthin on visual function in healthy individuals: a randomized, double-blind, placebo-controlled, parallel study. Journal of Clinical Biochemistry and Nutrition — PubMed PMID: 36777084
  2. Kizawa Y, Sekikawa T, Kageyama M, et al. (2021). Effects of anthocyanin, astaxanthin, and lutein on eye functions: a randomized, double-blind, placebo-controlled study. Journal of Clinical Biochemistry and Nutrition — PubMed PMID: 34376917
  3. Parisi V, Tedeschi M, Gallinaro G, et al. (2008). Carotenoids and antioxidants in age-related maculopathy italian study: multifocal electroretinogram modifications after 1 year. Ophthalmology — PubMed PMID: 17716735
  4. Piermarocchi S, Saviano S, Parisi V, et al. (2012). Carotenoids in Age-related Maculopathy Italian Study (CARMIS): two-year results of a randomized study. European Journal of Ophthalmology — PubMed PMID: 22009916
  5. Hashimoto H, Arai K, Hayashi S, et al. (2013). Effects of astaxanthin on antioxidation in human aqueous humor. Journal of Clinical Biochemistry and Nutrition — PubMed PMID: 23874063
  6. Saito M, Yoshida K, Saito W, et al. (2012). Astaxanthin increases choroidal blood flow velocity. Graefe's Archive for Clinical and Experimental Ophthalmology — PubMed PMID: 22072378
  7. Tian L, Wen Y, Li S, et al. (2021). Benefits and Safety of Astaxanthin in the Treatment of Mild-To-Moderate Dry Eye Disease. Frontiers in Nutrition — PubMed PMID: 35096941
  8. Huang JY, Yeh PT, Hou YC (2016). A randomized, double-blind, placebo-controlled study of oral antioxidant supplement therapy in patients with dry eye syndrome. Clinical Ophthalmology — PubMed PMID: 27274185
  9. Janani R, Anitha RE, Perumal MK, et al. (2021). Astaxanthin mediated regulation of VEGF through HIF1α and XBP1 signaling pathway: An insight from ARPE-19 cell and streptozotocin mediated diabetic rat model. Experimental Eye Research — PubMed PMID: 33789142
  10. Benlarbi-Ben Khedher M, Hajri K, Dellaa A, et al. (2019). Astaxanthin inhibits aldose reductase activity in Psammomys obesus, a model of type 2 diabetes and diabetic retinopathy. Food Science & Nutrition — PubMed PMID: 31890176
  11. Tanaka-Gonome T, Xie Y, Yamauchi K, et al. (2020). The protective effect of astaxanthin on the ganglion cell complex in glutamate/aspartate transporter deficient mice, a model of normal tension glaucoma, analyzed by spectral domain-optical coherence tomography. Biochemistry and Biophysics Reports — PubMed PMID: 32637659
  12. Giannaccare G, Pellegrini M, Senni C, et al. (2020). Clinical Applications of Astaxanthin in the Treatment of Ocular Diseases: Emerging Insights. Marine Drugs — PubMed PMID: 32370045
  13. Nishida Y, Berg PC, Shakersain B, et al. (2023). Astaxanthin: Past, Present, and Future. Marine Drugs — PubMed PMID: 37888449
  14. Shimidzu N, Goto M, Miki W (1996). Carotenoids as Singlet Oxygen Quenchers in Marine Organisms. Fisheries Science 62(1):134–137 — doi:10.2331/fishsci.62.134
  15. Manabe Y, Komatsu T, Seki S, et al. (2018). Dietary astaxanthin can accumulate in the brain of rats. Bioscience, Biotechnology, and Biochemistry — PubMed PMID: 29625535
  16. Ambati RR, Phang SM, Ravi S, et al. (2014). Astaxanthin: sources, extraction, stability, biological activities and its commercial applications--a review. Marine Drugs — PubMed PMID: 24402174
  17. Satti HH, Khaleel EF, Badi RM, et al. (2021). Antiplatelet activity of astaxanthin in control- and high cholesterol-fed rats mediated by down-regulation of P2Y12, inhibition of NF-κB, and increasing intracellular levels of cAMP. Platelets — PubMed PMID: 32379559
  18. Ursoniu S, Sahebkar A, Serban MC, et al. (2015). Lipid profile and glucose changes after supplementation with astaxanthin: a systematic review and meta-analysis of randomized controlled trials. Archives of Medical Science — PubMed PMID: 25995739
  19. Xia W, Tang N, Kord-Varkaneh H, et al. (2020). The effects of astaxanthin supplementation on obesity, blood pressure, CRP, glycemic biomarkers, and lipid profile: A meta-analysis of randomized controlled trials. Pharmacological Research — PubMed PMID: 32755613
  20. Brendler T, Williamson EM (2019). Astaxanthin: How much is too much? A safety review. Phytotherapy Research — PubMed PMID: 31788888
  21. EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), Turck D, Castenmiller J, et al. (2020). Safety of astaxanthin for its use as a novel food in food supplements. EFSA Journal — PubMed PMID: 32874213

PubMed Topic Searches

  1. PubMed: astaxanthin eye vision
  2. PubMed: astaxanthin macular degeneration
  3. PubMed: astaxanthin asthenopia eye strain
  4. PubMed: astaxanthin blue light retina
  5. PubMed: astaxanthin diabetic retinopathy
  6. PubMed: astaxanthin dry eye tear film
  7. PubMed: lutein zeaxanthin astaxanthin combination

Back to Table of Contents

Connections

Back to Table of Contents