The global sports nutrition market exceeded $50 billion in 2024, with a pronounced shift toward clean-label, plant-based performance ingredients. For ingredient buyers and sports nutrition brand formulators, the key question is not whether an ingredient "sounds good" — it's whether randomised controlled trials (RCTs) support the performance claims. On that criterion, the scientific case for spirulina as a sports nutrition ingredient has never been stronger than it is in 2025.
This article reviews the most recent clinical evidence, including trials published in 2024 and 2025, and explains precisely what spirulina does — and doesn't do — for athletic performance.
The Haemoglobin Hypothesis: Why Spirulina May Work
Spirulina's performance benefits are thought to operate primarily through a haemoglobin-mediated mechanism. Spirulina is exceptionally rich in bioavailable iron (approximately 28 mg per 100g, far exceeding spinach at 2.7 mg per 100g) and phycocyanin itself contains phycocyanobilin, a bilirubin precursor that directly supports red blood cell synthesis and haem metabolism.
More haemoglobin means greater oxygen-carrying capacity in the blood. Greater oxygen-carrying capacity means better oxygen delivery to working muscles. This is the same physiological principle underlying altitude training — the most validated ergogenic strategy in elite sport. Spirulina essentially provides a nutritional parallel to altitude exposure, without the logistical complexity.
The Altitude Study: A Landmark 2025 RCT
The most methodologically rigorous recent trial comes from Kingston University and University College London, published in the Journal of the International Society of Sports Nutrition in May 2025 (DOI: 10.1080/15502783.2025.2498484). Researchers Gurney, Brouner and Spendiff enrolled 20 healthy cyclists (18 male, 2 female; mean V̇O₂max 51.8 ml·kg⁻¹·min⁻¹) in a double-blinded, randomised, counter-balanced crossover design. Participants ingested 6g/day of spirulina or placebo for 3 weeks, then completed a lactate threshold test at simulated moderate altitude of 2,500 metres.
The key finding: three weeks of spirulina supplementation at 6g/day significantly reduced heart rate during the lactate threshold test at simulated altitude. A lower heart rate at equivalent workload means the cardiovascular system is working more efficiently — a direct performance benefit for endurance athletes competing at altitude or in hot, oxygen-depleted conditions.
The Earlier Cycling RCT: Submaximal Performance
A 2024 study published in the Journal of Dietary Supplements (DOI: 10.1080/19390211.2023.2263564, Ali, Aubeeluck & Gurney) examined spirulina's effect across 21 days in trained cyclists. The trial found that spirulina supplementation lowered heart rate during submaximal cycling — again pointing to improved cardiovascular efficiency — and augmented power output during repeated sprint protocols, a finding directly relevant to cyclists, team sport athletes, and fighters who need to sustain explosive efforts over time.
VO₂ Max, Time to Fatigue, and Fat Oxidation
Earlier but equally well-designed research established three additional performance benefits of spirulina:
1. Improved oxygen uptake — Gurney & Spendiff (2020, European Journal of Applied Physiology; DOI: 10.1007/s00421-020-04487-2) showed spirulina supplementation significantly improved oxygen uptake during arm cycling exercise in a controlled clinical trial. This improved VO₂ is directly linked to haemoglobin elevation.
2. Extended time to fatigue — A crossover RCT in which subjects ran at 70-75% of VO₂ max to exhaustion found that the spirulina group ran longer before reaching fatigue — with significantly higher time to exhaustion after spirulina versus placebo. The mechanism involved enhanced fat oxidation, sparing muscle glycogen during the submaximal phase.
3. Muscle metabolism adaptation — A 2025 study from Le Mans Université (Nutrients, DOI: 10.3390/nu17020283; Vignaud et al., January 2025) examined the combined effects of spirulina liquid extract and endurance training on aerobic performance and muscle metabolism in a controlled trial, finding synergistic adaptations in mitochondrial enzyme activity in the spirulina + training group versus training alone.
What Sports Nutrition Brands Need to Know
The clinical evidence points to spirulina as an effective ingredient in three specific contexts:
- Endurance sports (cycling, running, triathlon, rowing): haemoglobin and VO₂ benefits are most pronounced in these disciplines
- Altitude preparation: the 2025 Gurney et al. data make a strong case for spirulina in altitude training camps
- Recovery formulations: the antioxidant and anti-inflammatory properties documented in our companion article [C-Phycocyanin as an Anti-Inflammatory Agent: What the Science Actually Says] also support post-exercise recovery
The effective clinical dose across all trials is consistently 6g/day of spirulina powder, with benefits emerging after 2–4 weeks of supplementation.
Ingredient Quality Matters
Critically, the spirulina used in these clinical trials was standardised, certified material — not generic bulk powder of uncertain provenance. The phycocyanin content, protein content, and microbiological profile all vary significantly between producers. For sports nutrition applications, procure spirulina with:
- NABL-accredited Certificate of Analysis (COA) per batch
- Documented protein content ≥60% dry weight
- Heavy metals panel within EFSA/USP limits
- USDA Organic or equivalent certification
→ See our guide: [The $200M Phycocyanin Market: Opportunity, Pricing, and What Global Buyers Are Looking For in 2026]
Scientific References
Gurney T, Brouner J, Spendiff O. (2025). "Physiological effects of spirulina supplementation during lactate threshold exercise at simulated altitude (2,500 m): a randomized controlled trial." Journal of the International Society of Sports Nutrition, 22(1):2498484. DOI: 10.1080/15502783.2025.2498484. PMC12046610.
Ali Y, Aubeeluck R, Gurney T. (2024). "Twenty-one days of spirulina supplementation lowers heart rate during submaximal cycling and augments power output during repeated sprints in trained cyclists." Journal of Dietary Supplements, 21(3):261-280. DOI: 10.1080/19390211.2023.2263564. PMID: 37807529.
Gurney T, Spendiff O. (2020). "Spirulina supplementation improves oxygen uptake in arm cycling exercise." European Journal of Applied Physiology, 120(12):2657-2664. DOI: 10.1007/s00421-020-04487-2. PMID: 32892320.
Vignaud J et al. (2025). "Combined Effects of Spirulina Liquid Extract and Endurance Training on Aerobic Performance and Muscle Metabolism Adaptation in Wistar Rats." Nutrients, 17(2):283. DOI: 10.3390/nu17020283. PMC11769088.
Rahnama I et al. (2023). "The effect of Spirulina supplementation on lipid profile: GRADE-assessed systematic review and dose-response meta-analysis of data from randomized controlled trials." Pharmacological Research, 193:106802. DOI: 10.1016/j.phrs.2023.106802. PMID: 37263369.
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About the Author
Spiruva Research Team
Industry Intelligence Desk
Spiruva's editorial team includes co-founders and industry researchers covering the global phycocyanin and spirulina markets. We publish data-driven articles that help B2B buyers make better procurement decisions.