Effect of astaxanthin on cycling time trial performance
Participants
n=21 competitive cyclists (14 completed: 7 astaxanthin, 7 placebo)
Protocol
4 mg/day astaxanthin or placebo, 28 days
Test: 2h at ~LT4 (preload), then 20 km TT
Key Results
| Metric | Astaxanthin | Placebo |
|---|---|---|
| 20 km TT | −121s (95% CI: −185, −53) | −19s (CI: −84, +45, ns) |
Findings
28 days of 4 mg astaxanthin → significant TT improvement after preload. But: small sample, high dropout (7/21).
Practical Application
In 21 competitive cyclists randomly assigned to astaxanthin (4 mg/d) or placebo for 28 d, of whom fourteen completed (7 per group), 20 km time-trial time after a 2 h pre-exhaustion ride improved by 121 s with astaxanthin (95% CI -185, -53) versus 19 s with placebo (95% CI -84, 45), and power output rose 20 W versus 1.6 W (RCT, Earnest 2011) — a single small trial with no identified mechanism: carbohydrate and fat oxidation and blood fuel-mobilisation indices showed no treatment effect.
Inference, not tested here: with only fourteen of 21 randomised cyclists completing and the mechanism "obscure" (the authors' word), treat astaxanthin as an unproven supplement rather than a recommendation; the cross-referenced trials point in different directions.
Limitations
Very small sample (n=7 per group); high dropout (33%); low dose (4 mg); results potentially inflated by dropout bias
How this entry was checked and changed
Content correction 2026-09-27
2026-09-28: added Practical Application from the abstract (Europe PMC PMID 21984399).