Spirulina
Arthrospira platensis
TL;DR
Spirulina is a protein- and phycocyanin-rich cyanobacterium with surprisingly good human trial evidence for allergic rhinitis and modest effects on blood lipids and blood pressure. Quality matters: choose brands tested for microcystins and heavy metals.
Ideal For
- People with seasonal allergic rhinitis seeking an adjunct
- Those wanting a whole-food source of antioxidants and protein
Avoid If
- You have phenylketonuria (contains phenylalanine)
- You have an autoimmune condition on immunosuppressants (theoretical immune stimulation)
- The product lacks third-party testing for microcystins/heavy metals
- You rely on it for vitamin B12
Frequently Asked Questions
Overview
Spirulina (Arthrospira platensis) is a dried cyanobacterium biomass, ~60% protein by weight, containing phycocyanin, beta-carotene, and gamma-linolenic acid. Its best-supported use is allergic rhinitis: randomised trials (including a placebo-controlled study using 2 g/day) showed significant reductions in nasal discharge, sneezing and congestion versus placebo, likely via Th2 suppression and reduced histamine release. Meta-analyses of RCTs report small but significant reductions in total cholesterol, LDL and triglycerides, and modest blood-pressure reductions (~4-5 mmHg systolic). Antioxidant and anti-inflammatory effects are plausible via phycocyanin inhibition of NADPH oxidase. Marketing claims about B12 are misleading: spirulina contains pseudovitamin B12 analogues that are not bioactive in humans and may even interfere with true B12 absorption. Detox and immunity claims are largely unsupported beyond small trials. Contamination with microcystins and heavy metals in low-quality products is a genuine concern.
How It Works
- Phycocyanin inhibits NADPH oxidase, reducing oxidative stress
- Suppresses Th2 cytokines and histamine release from mast cells
- Modest inhibition of cholesterol absorption and synthesis
- Nitric-oxide-mediated vasodilation contributing to small BP reductions
Benefits & Outcomes
Allergy Relief
One well-known RCT showed spirulina improved allergic rhinitis symptoms versus placebo.
Histamine Balance
Spirulina reduced allergic rhinitis symptoms versus placebo in a randomized trial — a promising adjunct with anti-inflammatory immune modulation.
Supporting Research9 studies
The effect of spirulina supplementation on lipid profile: GRADE-assessed systematic review and dose-response meta-analysis of data from randomized controlled trials
Rahnama I, Arabi SM, Chambari M +4 more
Spirulina improves lipid profile, but the evidence certainty limits strong recommendations.
The effects of spirulina on allergic rhinitis
Cingi C, Conk-Dalay M, Cakli H +1 more
Spirulina consumption significantly improved the symptoms and physical findings compared with placebo (P < 0.001) including nasal discharge, sneezing, nasal congestion and itching. Spirulina is clinically effective on allergic rhinitis when compared with placebo.
Clinical comparison of the efficacy of spirulina platensis and cetirizine for treatment of allergic rhinitis
Nourollahian M, et al
Spirulina is more effective than cetirizine in improving cardinal symptoms of AR patients.
Effects of spirulina (Arthrospira) platensis supplementation on inflammation, quality of life, and anthropometric measures
et al
Spirulina supplementation reduced circulating inflammatory markers and improved patient-reported quality of life versus placebo.
Effect of spirulina supplementation on systolic and diastolic blood pressure: systematic review and meta-analysis of randomized controlled trials
Machowiec P, Reka G, Maksymowicz M +2 more
Spirulina supplementation is associated with a significant reduction in blood pressure.
The role of Chlorella and Spirulina as adjuvants of cardiovascular risk factor control: a systematic review and meta-analysis of randomised controlled trials
Pinto-Leite M, Martins D, Ferreira AC +1 more
Spirulina may act as a modest adjuvant for cardiovascular risk factor control, not a replacement for standard therapy.
The effect of different doses of spirulina on glucose metabolism, lipid profile and blood pressure: a systematic review and meta-analysis of randomized controlled trials
Chaloulakou S, Lympaki F, Tsitsou S +2 more
Spirulina benefits cardiometabolic markers unevenly, with glucose outcomes largely unchanged.
Clinical comparison of the efficacy of spirulina platensis and cetirizine for treatment of allergic rhinitis
Nourollahian M, Rasoulian B, Gafari A +3 more
Spirulina may provide symptom relief in allergic rhinitis comparable to a standard antihistamine.
Hypolipidemic effect of Arthrospira (Spirulina) maxima supplementation and a systematic physical exercise program in overweight and obese men: a double-blind, randomized, and crossover controlled trial
Hernandez-Lepe MA, Lopez-Diaz JA, Juarez-Oropeza MA +3 more
Spirulina modestly improves lipids, with additive benefit from structured exercise.
Safety Information
Potential Side Effects
Generally well tolerated; occasional GI upset, headache. Rare reports of allergic reactions. Contaminated products have caused liver injury.
Contraindications
Phenylketonuria; known algae allergy.
Drug Interactions
- Theoretical additive effect with immunosuppressants
- Anticoagulants (vitamin K content is low but variable)
Pregnancy & Breastfeeding
Pregnancy: insufficient_data
Breastfeeding: insufficient_data
Dosage Guidelines
Dosage Used in Studies
1-8 g
Best Time to Take
Divided with meals
Best Form
Third-party tested (NSF/USP or equivalent) powder or tablets
Dosing by Goal
| Goal | Dose | Notes |
|---|---|---|
| 2 g/day | Dose used in placebo-controlled RCT | |
| 1-8 g/day | Meta-analysis range; 2-4.5 g common |
Forms Compared
Most economical; strong taste; verify third-party testing
Convenient; 500 mg tablets mean many pills for 2-3 g/day
Food & Timing
With or without food.
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.