Spirulina for Athletes: What a Systematic Review Says About Antioxidant and Performance Effects
Arthrospira platensis — spirulina — is a blue-green algae supplement built almost entirely around its bioactive-compound density: up to 65% protein by dry weight, plus phycocyanin, beta-carotene, chlorophyll, and other antioxidant pigments. It’s been used as a food supplement since the 1960s, and anecdotally credited (the Chinese and Cuban Olympic teams are the usual reference point) with supporting athletic performance. A 2022 systematic review in Frontiers in Nutrition took a more rigorous look, pooling 13 controlled trials to ask what spirulina actually does for people who exercise.
What the Review Covered
Researchers screened 981 studies down to 13 that met their criteria: randomized trials measuring spirulina’s effect on oxidative stress, inflammation, immune function, or exercise performance in people who train regularly, at doses ranging from 1.5 to 7.5 g per day over 3 to 8 weeks in most studies (one ran 12 weeks). Five trials involved competitive athletes; the rest, trained or untrained people undergoing structured exercise.
Where the Evidence Actually Points
Antioxidant Effects: Real, but Inconsistent
Two studies found spirulina significantly lowered malondialdehyde (a marker of oxidative lipid damage) and raised superoxide dismutase activity — one of the body’s core antioxidant enzymes. But the effect wasn’t universal: it didn’t show up in elite rugby players or in cyclists with adequate baseline nutritional status, suggesting spirulina’s antioxidant benefit may matter most for people whose diet is already short on antioxidants, rather than as a universal booster.
An Ergogenic Effect — For Endurance, Not Power
The clearest pattern in the review: spirulina supplementation (6–7.5 g/day) improved oxygen uptake, hemoglobin levels, and fatigue tolerance during submaximal endurance exercise in cyclists and runners. It did not improve performance in power-based efforts like sprint tests or vertical jump. One proposed mechanism is spirulina’s naturally high, easily absorbed iron content, supporting the hemoglobin synthesis that endurance performance depends on.
Recovery and Immune Function: Not Enough Data Yet
One study on elite rugby players found spirulina accelerated recovery of inflammation and muscle-damage markers (CRP, creatine kinase) after intense training, but most other studies found no benefit on muscle recovery markers. Immune effects were assessed in only a single trial, on rowers, with mixed and inconclusive results. The review is explicit that evidence for immune benefits from spirulina “remains scarce,” and it’s premature to recommend it for that purpose.
The Bottom Line
Across 13 controlled trials, the most defensible claim for spirulina in athletes is a modest ergogenic effect during submaximal endurance exercise — better oxygen uptake and fatigue tolerance — particularly in people not already meeting recommended antioxidant intake through diet. Claims about immune support, muscle recovery, or power performance are not well supported by the current trial record, and the review itself calls for larger, higher-quality studies (most of the 13 trials included carried a high or unclear risk of bias) before drawing firmer conclusions.
References
[1] Calella, P.; Cerullo, G.; Di Dio, M.; Liguori, F.; Di Onofrio, V.; Gallè, F.; Liguori, G. “Antioxidant, anti-inflammatory and immunomodulatory effects of spirulina in exercise and sport: A systematic review.” Front. Nutr. 2022, 9:1048258. https://doi.org/10.3389/fnut.2022.1048258 (open access)
