Astaxanthin (The Marine Carotenoid)

Table of Contents

1. Biochemistry & Membrane Behavior
2. Marine Ecology: From Microalgae to Salmon Flesh
3. Antioxidant Potency & Singlet-Oxygen Quenching
4. The Pro-Oxidant Question (The Beta-Carotene Lesson)
5. Eye Health & Vision (AMD, Eye Strain)
6. Skin: The Internal Sunscreen
7. Cardiovascular & Lipid Effects
8. Exercise Performance & Muscle Recovery
9. Brain & Neuroprotection
10. Joint Inflammation & Systemic Anti-Inflammatory Effects
11. Male Fertility & Sperm Quality
12. Forms: Natural Haematococcus vs Synthetic, Esterified vs Free
13. Doses Used in Trials and Intake Limits
14. Cautions and Contraindications
15. Key Research Papers
16. Connections
17. Featured Videos

Biochemistry & Membrane Behavior

Astaxanthin (3,3'-dihydroxy-β,β-carotene-4,4'-dione) belongs to the xanthophyll subclass of carotenoids — the oxygen-containing carotenoids, as distinct from the hydrocarbon carotenes such as beta-carotene and lycopene. Its structure is essentially beta-carotene with a hydroxyl group (−OH) and a keto group (=O) added to each of the two end rings, which makes the molecule more polar at its ends than in its middle. Astaxanthin has no provitamin A activity in the human body (Ambati 2014).

A 2023 review describes the molecule's light-absorbing system as a chain of 11 conjugated carbon–carbon double bonds extended by the two keto groups, 13 conjugated double bonds in all (Nishida 2023). This conjugated chain is what absorbs light (giving the red color) and what reacts with singlet oxygen and free radicals.

The polar end groups affect how astaxanthin behaves in cell membranes. In a liposome study, astaxanthin was about twice as effective as beta-carotene at limiting iron-induced lipid peroxidation; the authors concluded that astaxanthin's end rings trapped radicals at the membrane surface while its polyene chain trapped them inside the membrane, whereas only beta-carotene's polyene chain was involved (Goto 2001). In an X-ray diffraction study of model membranes rich in polyunsaturated fatty acids, astaxanthin preserved membrane structure and lowered lipid hydroperoxide levels by 40%, while the apolar carotenoids beta-carotene and lycopene disordered the bilayer and raised hydroperoxide levels by more than 85% (McNulty 2007). Both are laboratory membrane models, not studies in people.

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Marine Ecology: From Microalgae to Salmon Flesh

Astaxanthin is made by a small number of microorganisms and then moves up the aquatic food chain:

• Haematococcus pluvialis — a green freshwater microalga that accumulates large amounts of astaxanthin under stress such as high salinity, nitrogen deficiency, high temperature and strong light, storing it in encysted cells. A 2014 review tabulates astaxanthin contents of 2.7% to 3.8% of dry weight across H. pluvialis strains, and names it one of the best natural sources (Ambati 2014). It is the main natural source for human consumption.
• Phaffia rhodozyma (Xanthophyllomyces dendrorhous) — a red yeast. The same review lists Phaffia yeast, Haematococcus and chemical synthesis as the main commercial sources (Ambati 2014).

Krill, shrimp, crab, lobster and crayfish carry astaxanthin, and salmon and trout deposit it in their muscle, which is what makes their flesh pink to red. A 2014 review reports 26–38 mg of astaxanthin per kg of flesh in wild sockeye salmon (the highest of the wild Pacific species listed, with chum salmon low), against 6–8 mg per kg in farmed Atlantic salmon (Ambati 2014). A 2023 review gives 2.0–3.8 mg per 100 g for sockeye salmon muscle and eggs (Nishida 2023). In a 2008 feeding trial, the wild and farmed salmon served both provided 5 µg of astaxanthin per gram of flesh (Rüfer 2008), so individual fish vary.

Farmed salmon get their astaxanthin from feed. United States regulations list synthetic astaxanthin, Haematococcus algae meal and Phaffia yeast as color additives permitted in the feed of salmonid fish “to enhance the pink to orange-red color of the flesh,” each capped at 80 mg of astaxanthin per kg of finished feed (21 CFR 73.35, 73.185 and 73.355). The source leaves a chemical fingerprint: synthetic astaxanthin is a mixture of three stereoisomers, and a laboratory method published in 1997 uses the isomer pattern in the flesh to tell wild salmon from farmed salmon fed synthetic astaxanthin (Turujman 1997). A 2025 analysis found higher levels of the natural 3S,3'S form, and of EPA and DHA, in wild than in farmed salmon; cooking did not change the 3S,3'S level, but canned salmon had less (Lu 2025).

For supplements, the natural form is extracted from cultivated H. pluvialis; the 2014 review reports yields of 80%–90% by supercritical-fluid extraction using ethanol and sunflower oil as co-solvents, among other solvent and acid methods (Ambati 2014).

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Antioxidant Potency & Singlet-Oxygen Quenching

Singlet oxygen (¹O₂) is an excited, highly reactive form of oxygen produced when light energy is transferred to oxygen by light-absorbing molecules, as can happen in skin and in the eye. The enzymes superoxide dismutase and catalase act on superoxide and hydrogen peroxide, not on singlet oxygen. Carotenoids deactivate (“quench”) singlet oxygen mainly by absorbing its excess energy, and astaxanthin is among the fastest quenchers measured in laboratory assays.

Where “6,000 times vitamin C” comes from. The widely repeated figure traces to a 2007 chemiluminescence assay published in Carotenoid Science by Nishida, Yamashita and Miki, authors who include researchers employed by an astaxanthin manufacturer. The assay 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: astaxanthin 5.4, beta-carotene 1.1, alpha-tocopherol (vitamin E) 0.049, coenzyme Q10 (ubiquinone-10) 0.0068 and vitamin C 0.00089 (Nishida 2023). An earlier comparison of carotenoids from marine organisms by Shimidzu, Goto and Miki (1996) is also commonly cited for these comparisons. In the other assays listed in the same review table, the gap between astaxanthin and beta-carotene ranged from none (2.2 for each) to large, and the review notes that in phospholipid membrane models astaxanthin sometimes showed a lower rate constant than beta-carotene, depending on the detection system.

What these numbers measure is a reaction speed in a test tube. They do not measure how much astaxanthin reaches a tissue, how long it stays, or whether anything clinical changes. The same caution applies to ORAC (oxygen radical absorbance capacity) scores: the USDA published an ORAC table for foods and withdrew it in 2012, stating that test-tube antioxidant values cannot be extrapolated to effects in people and that ORAC values were routinely misused to promote foods and supplements. No ORAC number is used on this page.

The intervention trials discussed on this page used daily doses from 2 mg (Park 2010) to 40 mg (Kim 2011), and a pharmacokinetic study used a single 100 mg dose (Østerlie 2000). Their results are described section by section below.

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The Pro-Oxidant Question (The Beta-Carotene Lesson)

Two large trials in the 1990s changed how researchers thought about antioxidant supplements:

• ATBC trial (Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, Finland, 1994) — 29,133 male smokers aged 50 to 69 were randomized to beta-carotene 20 mg/day, vitamin E (alpha-tocopherol 50 mg/day), both, or placebo, with five to eight years of follow-up. Lung cancer incidence was 18% higher among the men who received beta-carotene, and total mortality was 8% higher.
• CARET trial (Beta-Carotene and Retinol Efficacy Trial, US, 1996) — 18,314 smokers, former smokers and asbestos-exposed workers were randomized to beta-carotene 30 mg plus 25,000 IU of retinol (as retinyl palmitate) per day, or placebo. The relative risk of lung cancer in the active group was 1.28 and the relative risk of death from any cause 1.17, and the trial was stopped 21 months earlier than planned.

One explanation offered for these results is that carotenoids can act as pro-oxidants under some conditions, particularly at high oxygen pressure (Nishida 2023). Laboratory work is where astaxanthin and beta-carotene have been compared on this point: in the membrane model described above, beta-carotene and lycopene raised lipid hydroperoxide levels while astaxanthin lowered them (McNulty 2007), and in human skin cells exposed to UVA light, beta-carotene increased membrane damage while astaxanthin counteracted the UVA-induced changes (Camera 2009). These are cell and membrane studies.

No long-term outcome trial comparable to ATBC or CARET has tested astaxanthin, so whether the laboratory difference holds in people at high oxidative stress is not known. The human data on smokers are short-term biomarker studies: in a 3-week study of 39 heavy smokers given 5, 20 or 40 mg/day (no placebo arm), plasma malondialdehyde and isoprostane, two markers of lipid oxidation, fell from baseline in all dose groups (Kim 2011).

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Eye Health & Vision (AMD, Eye Strain)

The retina is exposed to focused light and is rich in polyunsaturated fatty acids that are vulnerable to oxidation. The macula concentrates two other carotenoids, lutein and zeaxanthin. Astaxanthin is studied for the eye because of its light-related antioxidant chemistry; the human trials so far are small.

Clinical evidence in eye health

• Eye strain and screen work — In a randomized, placebo-controlled trial in 60 healthy adults, 9 mg/day astaxanthin for 6 weeks preserved corrected visual acuity after screen work in participants aged 40 and over; there was no difference in those under 40, and none in functional visual acuity or pupil constriction (Sekikawa 2023; sponsored by a supplement maker, with employee authors). A combination product containing anthocyanins, astaxanthin and lutein improved some accommodation and symptom measures after 6 weeks (Kizawa 2021), but the effect of astaxanthin alone cannot be separated. Earlier Japanese accommodation trials (Nagaki 2002, Iwasaki 2006, Nakamura 2004) are often cited; they appeared in Japanese-language journals not indexed in PubMed and could not be checked here.
• Age-related macular degeneration — In the CARMIS study, 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 (Parisi 2008). Because seven ingredients were given together, the trial does not show what astaxanthin itself contributed.
• Antioxidant activity inside 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; the fluid taken from the front of the eye (aqueous humor) then showed higher superoxide-scavenging activity and lower total hydroperoxides (Hashimoto 2013). This measured the aqueous humor, not the retina.

A 2020 review of eye studies concluded that longer clinical trials are needed to define dose, route and the composition of products (Giannaccare 2020).

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Skin: The Internal Sunscreen

UV radiation damages skin partly by generating reactive oxygen species. Astaxanthin is sometimes described as an “internal sunscreen”; it does not block UV, and the trials below measured skin responses, not sunburn prevention in daily life.

Clinical evidence in skin health

• UV response — In a 10-week randomized, placebo-controlled trial in 23 healthy Japanese adults, 4 mg/day astaxanthin increased the minimal erythema dose (the UV dose that produces visible reddening) compared with placebo and reduced the loss of skin moisture in the irradiated area (Ito 2018; the authors were employees of the sponsoring company). An earlier and often-cited Camera 2009 study was a cell-culture experiment in human dermal fibroblasts, not a trial in people.
• Wrinkles, elasticity and moisture — Tominaga 2012 reported two studies by authors including researchers at an astaxanthin manufacturer: an open-label, uncontrolled 8-week study in 30 women combining 6 mg/day oral astaxanthin with a daily topical astaxanthin solution, which reported improvements in crow's-feet wrinkles, age-spot size, elasticity, texture and moisture; and a 6-week randomized, placebo-controlled study in 36 men taking 6 mg/day orally, which reported improvements in crow's-feet wrinkles, elasticity and transepidermal water loss.
• Meta-analysis — A 2021 systematic review found eleven studies (nine randomized controlled trials of oral astaxanthin and two open-label studies). Pooled, oral astaxanthin improved skin moisture (SMD 0.53) and elasticity (SMD 0.77) but did not significantly reduce wrinkle depth (SMD −0.26) compared with placebo (Zhou 2021). A 2018 narrative review of astaxanthin and skin, often cited alongside it, describes the proposed photoprotective, antioxidant and anti-inflammatory mechanisms as “still debated” (Davinelli 2018).

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Cardiovascular & Lipid Effects

• Yoshida 2010 — 61 non-obese adults aged 25–60 with fasting triglycerides of 120–200 mg/dl were randomized to 0, 6, 12 or 18 mg/day for 12 weeks. LDL cholesterol and body mass index did not change. The 12 and 18 mg doses significantly reduced triglycerides, the 6 and 12 mg doses significantly raised HDL cholesterol, and adiponectin rose at 12 and 18 mg (Yoshida 2010). The abstract does not report percentage changes.
• Meta-analysis of lipids, 2015 — seven randomized trials (280 participants, ten treatment arms) showed no significant effect on total cholesterol, LDL, HDL or triglycerides; a slight glucose-lowering effect was observed (Ursoniu 2015).
• Meta-analysis of cardiometabolic markers, 2020 — fourteen articles: astaxanthin was not associated with changes in fasting glucose, HbA1c, total or LDL cholesterol, triglycerides, body weight, or systolic or diastolic blood pressure. HDL rose by 1.473 mg/dl on average, and CRP fell only in trials lasting 12 weeks or more or using more than 12 mg/day (Xia 2020).
• Adults at risk of metabolic syndrome, 2022 — a meta-analysis found marginal effects on total cholesterol and systolic blood pressure and a significant effect on LDL cholesterol, and called for more robust evidence (Leung 2022).

The meta-analyses therefore do not agree on blood lipids, and none found a clear blood-pressure effect. Related pages: CoQ10, omega-3 fatty acids and vitamin K2.

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Exercise Performance & Muscle Recovery

Exercise generates oxidative stress in skeletal muscle, and astaxanthin has been tested both for performance and for recovery. The results are mixed.

• Earnest 2011 — 21 competitive cyclists were randomized to 4 mg/day astaxanthin or placebo for 28 days; 14 completed the trial. The astaxanthin group improved its 20 km time-trial time by 121 seconds and its power output by 20 W, against 19 seconds and 1.6 W in the placebo group. The authors observed no effect on fat or carbohydrate oxidation and wrote that the mechanism “remains obscure” (Earnest 2011).
• Brown 2021 — in a crossover trial in 12 recreationally trained male cyclists, 12 mg/day for 7 days improved 40 km time-trial time by 1.2% (51 seconds) and raised fat oxidation late in the ride (Brown 2021).
• Aoi 2003 and 2008 — both were mouse studies: astaxanthin limited exercise-induced skeletal and cardiac muscle damage (2003) and increased fat use and running time to exhaustion (2008). They are often cited as if they included people; they did not.
• Reviews and meta-analyses — a 2017 narrative review (not a meta-analysis) concluded that benefits seen in mice “have yet to be consistently realized” in exercising humans, with equivocal data (Brown 2017). A 2024 meta-analysis of 11 trials in 346 healthy participants reported improved physical performance when astaxanthin was combined with regular training (SMD 0.62) (Liu 2024). A 2026 meta-analysis of 24 randomized trials found lower creatine kinase (SMD −0.45) after exercise but no significant improvement in VO₂max, time-trial performance or maximal power (Liu 2026).

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Brain & Neuroprotection

In rats, astaxanthin was detected in the hippocampus and cerebral cortex 4 and 8 hours after a single oral dose, and brain levels were higher after 5 days on a diet containing 0.1% astaxanthin (Manabe 2018; one author was employed by a company that sells astaxanthin). A 2024 systematic review of 59 studies on Alzheimer's disease, Parkinson's disease, multiple sclerosis, cerebrovascular disease and spinal cord injury found potential activity in cell and animal models, and no reported safety concerns (Adıgüzel 2024). These are not human results.

Human cognitive trials are few. Katagiri 2012 randomized 96 healthy middle-aged and older adults with age-related forgetfulness to astaxanthin 6 mg/day, 12 mg/day or placebo for 12 weeks. CogHealth battery scores improved in the 12 mg group, and Groton Maze Learning Test scores improved earlier in both astaxanthin groups than in the placebo group, but the authors wrote that the sample size was too small to show a significant difference between astaxanthin and placebo. A 2024 meta-analysis found a marginal effect on cognitive accuracy (SMD 0.12, 95% CI −0.02 to 0.26) and no significant effect on reaction time (Liu 2024).

Related pages: CoQ10, alpha lipoic acid, PQQ and omega-3 fatty acids.

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Joint Inflammation & Systemic Anti-Inflammatory Effects

Laboratory and animal studies describe effects of astaxanthin on inflammatory signaling; for example, in rats given 10 mg/kg/day for 30 days, astaxanthin inhibited NF-κB activity in platelets (Satti 2021). Human results on inflammatory markers are mixed:

• Healthy young women — in an 8-week randomized trial of 0, 2 or 8 mg/day (14 per group), plasma CRP was lower at week 8 with 2 mg and a DNA-damage marker fell, but plasma IL-6 and interferon-gamma rose with 8 mg (Park 2010).
• Pooled trials — CRP fell only in trials lasting at least 12 weeks or using more than 12 mg/day (Xia 2020).
• Rheumatoid arthritis — in a triple-blind trial, 60 patients received 20 mg/day astaxanthin or placebo for 8 weeks. Disease activity (DAS-28), disability (HAQ) and ESR fell significantly compared with placebo and remained significant after adjustment; pain and CRP were not significantly different after adjustment, and IL-6 did not change (Grigorian 2025).

Claims of benefit in osteoarthritis and tennis elbow, and comparisons with NSAIDs, were not supported by any trial found for this page.

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Male Fertility & Sperm Quality

Sperm membranes are rich in polyunsaturated fatty acids and vulnerable to oxidative damage, which has made antioxidants a research target in male infertility. Two randomized trials have tested astaxanthin, with different results:

• Comhaire 2005 — 30 infertile men received conventional treatment plus 16 mg/day astaxanthin or placebo for 3 months. Seminal reactive oxygen species and inhibin B fell and sperm linear velocity rose in the astaxanthin group (n = 11) but not in the placebo group (n = 19). Total pregnancy rates were 54.5% with astaxanthin and 10.5% with placebo. The authors wrote that the results “need to be confirmed in a larger trial.”
• Kumalic 2020 — 80 men with low sperm counts (with or without poor motility or morphology) received 16 mg/day astaxanthin or placebo for 3 months; among the 72 who completed the trial, astaxanthin did not change any semen parameter, sperm DNA fragmentation, mitochondrial membrane potential or FSH.

Related page: CoQ10.

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Forms: Natural Haematococcus vs Synthetic, Esterified vs Free

• Natural astaxanthin from Haematococcus pluvialis — occurs in the alga mainly as fatty-acid esters of the 3S,3'S stereoisomer, which makes up more than 90% of the carotenoids in the red cysts (Nishida 2023). Several of the trials on this page state an H. pluvialis source (for example Tominaga 2012, Katagiri 2012, Kim 2011).
• Synthetic astaxanthin — consists of the 3S,3'S, 3R,3'S (meso) and 3R,3'R isomers (Ambati 2014). After men ate wild salmon for 4 weeks, the 3S,3'S form made up 80% of the astaxanthin in their plasma; after farmed salmon, the meso form was the largest share at 48% (Rüfer 2008). A 2019 safety review argues that synthetic astaxanthin is chemically different from natural astaxanthin and that few safety studies in either humans or animals have used it (Brendler 2019).
• Esterified vs free — algal astaxanthin is mostly esterified (Nishida 2023). Krill, also among the natural sources, carries mainly the 3R,3'R form, largely esterified, while wild Atlantic salmon carry mainly 3S,3'S in the free form (Ambati 2014).
• Absorption — in three men given a single 100 mg dose of astaxanthin with a meal, plasma levels peaked at 6.7 hours and the elimination half-life was 21 ± 11 hours; astaxanthin travelled mainly in chylomicron and VLDL particles (Østerlie 2000).

Regulatory status

• United States — the FDA does not approve dietary supplements before they are marketed; under the Dietary Supplement Health and Education Act (DSHEA) it has no authority to do so (FDA, Questions and Answers on Dietary Supplements). Astaxanthin's FDA listings are as color additives for the feed of salmonid fish: synthetic astaxanthin (21 CFR 73.35), Haematococcus algae meal (21 CFR 73.185) and Phaffia yeast (21 CFR 73.355).
• European Union — in 2020 EFSA's nutrition panel assessed astaxanthin as a novel food in food supplements at up to 8 mg/day (see Safety, below).

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Doses Used in Trials and Intake Limits

There is no official recommended intake for astaxanthin. The figures below are what the cited trials and agencies report, not instructions.

• Skin — 4 mg/day for 10 weeks (Ito 2018); 6 mg/day for 6–8 weeks (Tominaga 2012).
• Eye — 9 mg/day for 6 weeks (Sekikawa 2023); 6 mg/day for 2 weeks before eye surgery (Hashimoto 2013); 4 mg/day within a seven-ingredient combination for 12 months (Parisi 2008).
• Blood lipids — 6, 12 or 18 mg/day for 12 weeks (Yoshida 2010).
• Exercise — 4 mg/day for 28 days (Earnest 2011); 12 mg/day for 7 days (Brown 2021).
• Cognition — 6 or 12 mg/day for 12 weeks (Katagiri 2012).
• Inflammation — 2 or 8 mg/day for 8 weeks (Park 2010); 20 mg/day for 8 weeks in rheumatoid arthritis (Grigorian 2025).
• Male fertility — 16 mg/day for 3 months (Comhaire 2005; Kumalic 2020).
• Smokers — 5, 20 or 40 mg/day for 3 weeks (Kim 2011).

Intake limits. EFSA's 2020 opinion concluded that 8 mg/day from food supplements, added to the astaxanthin people get from fish and crustaceans, is safe for adults. The acceptable daily intake it used, 0.2 mg per kg of body weight, had been set by EFSA's feed-additives panel in 2019, replacing an earlier 0.034 mg/kg. With 8 mg/day from supplements, adolescents aged 14 to under 18 reach that ADI, and children aged 10 to under 14 exceed it by 28% (EFSA 2020). A 2019 safety review found approved or recommended doses ranging from 2 to 24 mg across countries (Brendler 2019).

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Cautions and Contraindications

• Adverse events in trials — a 2019 review of 87 human studies of natural astaxanthin found none that reported safety concerns, 35 of them at 12 mg/day or more (Brendler 2019). In an 8-week safety trial of 6 mg/day in 35 adults, blood pressure and blood chemistry did not differ from placebo except for very small differences in serum calcium, total protein and eosinophils that the authors judged clinically unimportant (Spiller 2003). The trials cited here lasted from 7 days to 3 months, apart from the 12-month CARMIS combination study.
• Children and adolescents — EFSA's conclusion of safety at 8 mg/day from supplements applies to adults; the ADI is reached in adolescents aged 14 to under 18 and exceeded in children aged 10 to under 14 (EFSA 2020).
• Blood clotting — in rats, astaxanthin reduced platelet aggregation and prolonged bleeding time (Satti 2021). No clinical trial of astaxanthin taken with anticoagulant or antiplatelet drugs was found for this page, so the interaction is unstudied rather than known to be absent. Decisions about combining supplements with these medicines belong with a clinician.
• Blood pressure — pooled trials did not show a consistent effect on systolic or diastolic pressure (Xia 2020; Leung 2022).
• Pregnancy and breastfeeding — none of the trials cited on this page studied pregnant or breastfeeding women, and the EFSA summary states its conclusion for adults without addressing pregnancy.
• Synthetic astaxanthin — the 2019 safety review notes that few safety studies in humans or animals have used synthetic astaxanthin, and calls for further studies, including human clinical trials, to set a separate acceptable intake for it (Brendler 2019).

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Key Research Papers

1. 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
2. Nishida Y, Berg PC, Shakersain B, et al. (2023). Astaxanthin: Past, Present, and Future. Marine Drugs — PubMed PMID: 37888449
3. 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
4. Goto S, Kogure K, Abe K, et al. (2001). Efficient radical trapping at the surface and inside the phospholipid membrane is responsible for highly potent antiperoxidative activity of the carotenoid astaxanthin. Biochimica et Biophysica Acta — PubMed PMID: 11406102
5. McNulty HP, Byun J, Lockwood SF, et al. (2007). Differential effects of carotenoids on lipid peroxidation due to membrane interactions: X-ray diffraction analysis. Biochimica et Biophysica Acta — PubMed PMID: 17070769
6. Turujman SA, Wamer WG, Wei RR, et al. (1997). Rapid liquid chromatographic method to distinguish wild salmon from aquacultured salmon fed synthetic astaxanthin. Journal of AOAC International — PubMed PMID: 9170658
7. Rüfer CE, Moeseneder J, Briviba K, et al. (2008). Bioavailability of astaxanthin stereoisomers from wild (Oncorhynchus spp.) and aquacultured (Salmo salar) salmon in healthy men: a randomised, double-blind study. British Journal of Nutrition — PubMed PMID: 17967218
8. Lu P, Reisdorph N, Hendricks AE, et al. (2025). Characterization of astaxanthin isomers in different types of salmon filets and human plasma after salmon consumption. Food Chemistry — PubMed PMID: 40179560
9. Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group (1994). The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. New England Journal of Medicine — PubMed PMID: 8127329
10. Omenn GS, Goodman GE, Thornquist MD, et al. (1996). Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease. New England Journal of Medicine — PubMed PMID: 8602180
11. Camera E, Mastrofrancesco A, Fabbri C, et al. (2009). Astaxanthin, canthaxanthin and beta-carotene differently affect UVA-induced oxidative damage and expression of oxidative stress-responsive enzymes. Experimental Dermatology — PubMed PMID: 18803658
12. Kim JH, Chang MJ, Choi HD, et al. (2011). Protective effects of Haematococcus astaxanthin on oxidative stress in healthy smokers. Journal of Medicinal Food — PubMed PMID: 21883001
13. 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
14. 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
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22. Yoshida H, Yanai H, Ito K, et al. (2010). Administration of natural astaxanthin increases serum HDL-cholesterol and adiponectin in subjects with mild hyperlipidemia. Atherosclerosis — PubMed PMID: 19892350
23. 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
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25. Leung LY, Chan SM, Tam HL, et al. (2022). Astaxanthin Influence on Health Outcomes of Adults at Risk of Metabolic Syndrome: A Systematic Review and Meta-Analysis. Nutrients — PubMed PMID: 35631193
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28. Aoi W, Naito Y, Sakuma K, et al. (2003). Astaxanthin limits exercise-induced skeletal and cardiac muscle damage in mice. Antioxidants & Redox Signaling — PubMed PMID: 12626126
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33. 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
34. Adıgüzel E, Ülger TG (2024). A marine-derived antioxidant astaxanthin as a potential neuroprotective and neurotherapeutic agent: A review of its efficacy on neurodegenerative conditions. European Journal of Pharmacology — PubMed PMID: 38843946
35. Katagiri M, Satoh A, Tsuji S, et al. (2012). Effects of astaxanthin-rich Haematococcus pluvialis extract on cognitive function: a randomised, double-blind, placebo-controlled study. Journal of Clinical Biochemistry and Nutrition — PubMed PMID: 22962526
36. 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
37. Park JS, Chyun JH, Kim YK, et al. (2010). Astaxanthin decreased oxidative stress and inflammation and enhanced immune response in humans. Nutrition & Metabolism — PubMed PMID: 20205737
38. Grigorian A, Tabatabaeyan A, Salesi M, et al. (2025). Astaxanthin supplement improves clinical outcomes, quality of life, and inflammatory factors in patients with rheumatoid arthritis: a randomized clinical trial. Food & Function — PubMed PMID: 40569081
39. Comhaire FH, El Garem Y, Mahmoud A, et al. (2005). Combined conventional/antioxidant "Astaxanthin" treatment for male infertility: a double blind, randomized trial. Asian Journal of Andrology — PubMed PMID: 16110353
40. Kumalic SI, Klun IV, Bokal EV, et al. (2020). Effect of the oral intake of astaxanthin on semen parameters in patients with oligo-astheno-teratozoospermia: a randomized double-blind placebo-controlled trial. Radiology and Oncology — PubMed PMID: 33885235
41. Østerlie M, Bjerkeng B, Liaaen-Jensen S (2000). Plasma appearance and distribution of astaxanthin E/Z and R/S isomers in plasma lipoproteins of men after single dose administration of astaxanthin. Journal of Nutritional Biochemistry — PubMed PMID: 11120445
42. 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
43. Brendler T, Williamson EM (2019). Astaxanthin: How much is too much? A safety review. Phytotherapy Research — PubMed PMID: 31788888
44. Spiller GA, Dewell A (2003). Safety of an astaxanthin-rich Haematococcus pluvialis algal extract: a randomized clinical trial. Journal of Medicinal Food — PubMed PMID: 12804020

PubMed Topic Searches

1. Astaxanthin and eye health, asthenopia, accommodation — PubMed: astaxanthin eye asthenopia
2. Astaxanthin for age-related macular degeneration (AMD) — PubMed: astaxanthin macular degeneration
3. Astaxanthin anti-inflammatory effects (CRP, IL-6, NF-kB) — PubMed: astaxanthin inflammation
4. Astaxanthin vs beta-carotene: pro-oxidant chemistry — PubMed: astaxanthin vs beta-carotene pro-oxidant
5. Astaxanthin blood-brain barrier & blood-retinal barrier penetration — PubMed: astaxanthin blood-brain barrier
6. Astaxanthin membrane orientation & trans-membrane geometry — PubMed: astaxanthin membrane bilayer
7. Haematococcus pluvialis: production & commercial astaxanthin source — PubMed: Haematococcus pluvialis astaxanthin
8. Astaxanthin safety, pharmacokinetics, bioavailability — PubMed: astaxanthin safety bioavailability

External Authoritative Resources

1. Linus Pauling Institute — Carotenoids
2. NCCIH — Herbs and Supplements at a Glance
3. U.S. Food and Drug Administration. Questions and Answers on Dietary Supplements — FDA
4. 21 CFR 73.35 Astaxanthin (color additive, salmonid fish feed) — eCFR 73.35
5. 21 CFR 73.185 Haematococcus algae meal (color additive, salmonid fish feed) — eCFR 73.185
6. 21 CFR 73.355 Phaffia yeast (color additive, salmonid fish feed) — eCFR 73.355
7. U.S. Department of Agriculture, Agricultural Research Service. Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 (2010) — withdrawal notice, last modified 16 May 2012. — USDA ARS (archived copy)
8. PubMed — All research on astaxanthin

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