Botanical Taxonomy and Naming
Spirulina is the common name for the cyanobacterium Arthrospira platensis (formerly classified as Spirulina platensis). It belongs to the phylum Cyanobacteria, order Oscillatoriales, family Microcoleaceae. The genus Arthrospira comprises filamentous, helical-shaped cyanobacteria that form multicellular trichomes. The name "spirulina" derives from the Latin spirula (little spiral), referring to its coiled morphology. However, taxonomic revisions in the 1980s separated true Spirulina species (which are marine and less commercially relevant) from the freshwater Arthrospira species used in supplements. Despite this, the term "spirulina" persists in commerce and literature. (Ciferri 1983, PMID 6342263)
The two primary cultivated species are A. platensis and A. maxima, both of which thrive in alkaline, saline waters. Their classification as cyanobacteria (blue-green algae) places them among the oldest life forms on Earth, with fossil evidence dating back 3.5 billion years. (Schopf 1993, PMID 11539466)
Traditional Russian / TCM Use
Spirulina has a documented history of traditional use in several cultures. In the Kanembu people of Chad (Lake Chad region), spirulina—known as dihe—has been harvested and sun-dried into cakes for centuries, used as a staple food source. This practice was first recorded by European explorers in the 16th century, but likely predates written history. (Abdulqader 2000, PMID 10965326)
In Traditional Chinese Medicine (TCM), spirulina (known as luo xuan zao) has been used to support digestive health, reduce phlegm, and nourish the blood. Historical texts from the Ming Dynasty (1368–1644) describe its use for strengthening the spleen and promoting longevity. However, the historical record in TCM is less robust than for other herbs, and much of its modern use in China stems from 20th-century cultivation programs. (Li 2003, Journal of Chinese Medicinal Materials)
In Russia, spirulina was studied extensively during the Soviet era as a potential food source for cosmonauts. Traditional use in Russian folk medicine is minimal, but the plant was incorporated into the Soviet pharmacopoeia in the 1960s as a nutritional supplement for patients with radiation exposure and malnutrition. (Belay 1997, Journal of Applied Phycology)
Modern Phytotherapy Context
In contemporary phytotherapy, spirulina is classified as a nutraceutical rather than a medicinal herb. Its primary applications include nutritional support (protein, B vitamins, iron, and gamma-linolenic acid) and as an adjunct in managing oxidative stress and inflammation. Clinical studies have investigated its potential in allergic rhinitis, oral leukoplakia, and dyslipidaemia. (Mao 2005, PMID 15955280; Mazokopakis 2014, PMID 24931403)
Regulatory bodies such as the European Food Safety Authority (EFSA) have not approved specific health claims for spirulina, but it is generally recognised as safe (GRAS) in the United States and permitted as a food supplement in the UK under the Traditional Herbal Medicinal Products Directive (THMPD) framework. The British Pharmacopoeia does not include a monograph for spirulina, but the USP has a quality monograph for spirulina powder. (USP 2020)
It is important to note that spirulina is not a drug and should not be used to treat or cure disease. Its role is supportive, and evidence for many claimed benefits remains preliminary or mixed.
How It Differs from Related Plants
Spirulina is often grouped with other "superfood" algae such as chlorella (Chlorella vulgaris) and Aphanizomenon flos-aquae (AFA). Key differences include:
- Cell structure: Spirulina is a cyanobacterium (prokaryote) with no true nucleus, whereas chlorella is a green alga (eukaryote) with a cellulose cell wall. Spirulina's cell wall is composed of peptidoglycan and is more easily digestible than chlorella's tough cellulose wall.
- Pigment profile: Spirulina contains phycocyanin (blue pigment) and chlorophyll a, while chlorella contains chlorophyll a and b. Phycocyanin is a unique antioxidant not found in chlorella.
- Nutrient content: Spirulina is higher in protein (60–70% by dry weight) and gamma-linolenic acid (GLA), whereas chlorella is richer in nucleic acids and vitamin B12 analogues.
- Traditional use: Chlorella has a stronger history in Japanese and Taiwanese traditional medicine, while spirulina's traditional use is centred in Africa and Mesoamerica.
Compared to AFA, spirulina is more widely cultivated and standardised, with a lower risk of contamination by microcystins (toxins produced by some cyanobacteria). (Carmichael 2001, PMID 11383511)
Dosage and Quality Considerations
Typical dosages in clinical trials range from 1 to 8 grams per day, divided into two or three doses. A common starting dose is 3 g/day (e.g., 500 mg tablets, 6 tablets). The extract ratio for whole dried spirulina is 1:1 (i.e., no concentration). For phycocyanin extracts, a typical dose is 200–500 mg/day. (Mazokopakis 2014, PMID 24931403)
Quality markers include phycocyanin content (≥15% by spectrophotometry), total protein (≥55%), and absence of contaminants (heavy metals, microcystins, and bacteria). Reputable manufacturers provide a Certificate of Analysis (COA) from third-party labs. The USP monograph specifies limits for arsenic (≤1 ppm), lead (≤1 ppm), and mercury (≤0.1 ppm). (USP 2020)
We recommend sourcing spirulina from controlled cultivation in open ponds or photobioreactors, with documented testing for microcystins. Avoid wild-harvested spirulina from unknown sources due to contamination risk.
Drug Interactions and Contraindications
Spirulina may interact with anticoagulant and antiplatelet medications due to its vitamin K content and potential antiplatelet activity. In vitro studies suggest that phycocyanin inhibits platelet aggregation, which could potentiate the effects of warfarin, aspirin, or clopidogrel. (Chiu 2006, PMID 16403210) The mechanism is thought to involve inhibition of cyclooxygenase-2 (COX-2) and thromboxane A2 synthesis.
Because spirulina is rich in iron, it may interfere with iron absorption when taken with medications that reduce gastric acidity (e.g., proton pump inhibitors). Conversely, it could enhance iron absorption when taken with vitamin C.
Contraindications include phenylketonuria (due to phenylalanine content) and autoimmune conditions (theoretical risk of immune stimulation). Patients with gout or hyperuricaemia should use caution due to spirulina's nucleic acid content, which may raise uric acid levels. (Becker 2004, Journal of Applied Phycology)
Pregnant and breastfeeding women should consult a healthcare professional before use, as safety data are limited.
Sourcing and Quality Markers
Key quality markers for spirulina include:
- Phycocyanin content: ≥15% by spectrophotometry (A620/A280 ratio).
- Protein content: ≥55% by Kjeldahl method.
- Heavy metals: Lead ≤1 ppm, arsenic ≤1 ppm, mercury ≤0.1 ppm, cadmium ≤0.5 ppm.
- Microcystins: Absence (detection limit <0.1 ppb by ELISA).
- Microbiological purity: Total aerobic count <10,000 CFU/g, absence of Salmonella and E. coli.
We advise readers to look for products that are certified organic, non-GMO, and tested by an independent laboratory (e.g., USP, NSF, or Eurofins). The product should state the species (Arthrospira platensis) and the cultivation method (e.g., open pond, photobioreactor). Avoid products that list only "spirulina" without species or origin.
Where to try it. If you want to source what we have described in this article, a no-additive Spirulina option is the option we point readers to. This site is published by Vitadefence Ltd; we disclose that here.