Supplement analysis backed by scientific evidence · PT

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Limited evidenceLongevity & antioxidants

Astaxanthin

Astaxanthin is a potent antioxidant in the test tube and it does shift some blood biomarkers, but the changes are small and rarely map onto anything you would notice. Skin photoprotection is the most promising use; the endurance and eye-fatigue claims are weakly supported.

What the science says

  • Small reductions in oxidative stress and inflammation biomarkers Moderate evidence

    A meta-analysis of randomized controlled trials found astaxanthin mildly reduced malondialdehyde and increased superoxide dismutase, with inconsistent effects on CRP and IL-6. The authors described the effects as mild, and no trial has linked these biomarker shifts to clinical outcomes.

  • Protects skin from UV-induced deterioration Limited evidence

    A 16-week randomized double-blind trial in healthy adults found that 4 mg/day astaxanthin reduced the worsening of skin moisture loss and roughness that occurred in the placebo group after UV exposure, suggesting a protective rather than cosmetic-improvement effect. Sample sizes in skin trials are small (typically 20-65 per arm) and several are industry-funded.

  • Improves endurance performance Limited evidence

    Trials in cyclists and runners using 4-12 mg/day have produced mixed and mostly null results on time trial performance and substrate utilization. There is no reliable ergogenic effect at doses used in humans.

  • Reduces eye strain and improves visual function Limited evidence

    Small Japanese trials report improved accommodation and reduced asthenopia at 6 mg/day, but the studies are underpowered, poorly blinded in places, and largely sponsored. This claim should be considered unproven.

Dosage & safety

Studied doseCommon supplement doses are 4-12 mg/day of natural astaxanthin from Haematococcus pluvialis. Skin trials used 4-6 mg/day for 8-16 weeks; biomarker trials used 4-20 mg/day. Take with a fat-containing meal — absorption is poor on an empty stomach.
SafetyWell tolerated at doses up to 12 mg/day in trials lasting months. Reported side effects are minor: red-orange stool discoloration, mild GI upset, and occasionally lowered blood pressure. It has weak 5-alpha-reductase inhibitory activity in vitro, so theoretical hormonal effects at high doses have not been ruled out. May mildly lower blood pressure and inhibit platelet aggregation — caution with antihypertensives and anticoagulants. Avoid synthetic astaxanthin intended for aquaculture feed. Insufficient safety data in pregnancy and lactation.

Scientific references

Where to buy

Double Wood Supplements, Astaxanthin AstaReal®, 12 mg, 60 Softgels

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