What is spirulina?
Spirulina is a cyanobacterium — sometimes called blue-green algae, though technically it is a prokaryotic photosynthetic organism, not an algae in the strict sense. The species used in supplements is Arthrospira platensis, cultivated in controlled alkaline water conditions and dried into powder or tablets.
It has been used as a food source for centuries — by the Aztecs around Lake Texcoco and by communities around Lake Chad in Africa. Commercial production began in the 1970s. Today it is produced globally, with major production centres in Hawaii, Taiwan, India, and increasingly in Europe.
Why people take it
Spirulina’s nutritional profile is genuinely dense:
- Protein: 55–70% by dry weight, complete amino acid profile
- Iron: High content with good bioavailability
- Phycocyanin: The blue pigment — the primary bioactive compound
- Beta-carotene: Concentrated natural source
- B-vitamins: B1, B2, B3 in meaningful quantities
- GLA: A rare plant-source anti-inflammatory fatty acid
The evidence-based benefits (those with human clinical trials behind them) include: LDL cholesterol reduction, iron status improvement, allergic rhinitis symptom reduction, exercise oxidative stress reduction, and modest blood glucose improvement in diabetics.
What to expect (and not expect)
Be honest with yourself before starting. Spirulina is a food supplement with real nutritional benefits — it is not a miracle cure or a dramatic health transformation tool. Realistic expectations:
- If you are iron-deficient: a meaningful improvement in iron status over 4–8 weeks at 3–5 g/day with vitamin C.
- If you have elevated cholesterol: modest but real LDL improvement at 2–4.5 g/day over 2–3 months, as part of a broader dietary approach.
- For hay fever sufferers: potentially meaningful symptom reduction at 2 g/day — one of spirulina’s most consistently supported clinical benefits.
- General health: you will be adding a dense, well-tested food to your diet. Whether you notice this directly depends on your baseline diet and health.
How to choose a product
The most important factor in any spirulina purchase is quality testing. Spirulina accumulates heavy metals from its growth medium, and some cultivation is done in conditions that allow contamination. You need a product with:
- Third-party CoA for heavy metals (lead, arsenic, mercury, cadmium) from a named, accredited laboratory.
- Microcystin testing — ideally not detected, or clearly below regulatory limits.
- Disclosed phycocyanin content — above 14% indicates a well-handled product.
See the quality guide, CoA reading guide, and brand directory for specific recommendations.
Powder or tablets?
For beginners: tablets are easier. You can swallow them with water without tasting anything. Once you know you’ll stick with spirulina and have found a recipe vehicle you enjoy, switching to powder is more cost-effective. The nutrition is identical. See the powder vs tablets guide.
How much to take
Start small and build up. Jumping straight to 3 g/day frequently causes digestive discomfort (nausea, bloating) in the first week. Recommended progression:
- Days 1–7: 0.5–1 g/day
- Days 8–14: 1.5–2 g/day
- Days 15+: 2–3 g/day (or target dose for your specific goal)
Most people end up at 2–3 g/day for general supplementation. Higher doses (4–6 g/day) are used in some clinical applications (cholesterol, athletics). The dosage guide covers goal-specific doses.
How to take it without hating it
Spirulina tastes like the ocean. Strong, with a bitter back-note. Most people need a vehicle that masks this. The most reliable methods:
- Frozen banana smoothie — the gold standard. Banana sweetness and fat cover spirulina completely at 1–2 g.
- Cacao smoothie or energy balls — dark chocolate bitterness overwhelms spirulina bitterness.
- Tablets with water — no taste whatsoever.
For a full guide to making spirulina palatable, see How to make spirulina taste better. For specific recipes, see our recipe library.
Who should not take spirulina
Spirulina is not appropriate for everyone. Do not take spirulina if you have phenylketonuria (PKU). Get medical guidance first if you have autoimmune conditions, thyroid disorders, or are on immunosuppressant medication. See the complete safety and contraindications page.
Where to start on this site
- Benefits overview — evidence-graded summary of what spirulina does
- Quality guide — how to read a CoA
- Brand directory — tested producers by region
- Recipe library — 33 tested recipes
- Research hub — the actual studies