Spirulina

Cyanobacterium (Arthrospira platensis / maxima), supplement, plant protein source, marketed as «detox» and «superfood»

ATC code: A11JA-SPIRULINA (Spirulina (Arthrospira platensis / maxima))

Brand names – supplements

NOW Spirulina, Nutrex Hawaiian Spirulina, Pure Hawaiian Spirulina, BareOrganics Spirulina

Supplements are not tested in clinical trials and are not registered as medications.

Mechanism of action

Spirulina is a filamentous cyanobacterium, not an alga (although often called one). Dry mass is 60–70% protein and contains phycocyanin (pigment), chlorophyll, vitamin B12 analogues (biologically inactive in humans), B vitamins, poorly absorbed iron and beta-carotene. It is used as a food supplement and plant protein source. Spirulina has no pharmacological mechanism with a confirmed human target. in 2009 rejected all spirulina health claims (immunity, antioxidant effect, weight control) for lack of cause-and-effect substantiation. AESAN classifies it as a complemento alimenticio without therapeutic indication. and EFSA highlight the risk of microcystin contamination – hepatotoxins from other cyanobacteria – when spirulina is grown in open ponds without strain control.

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Dyslipidemia

Not recommended

Spirulina is an over-the-counter supplement. The Huang meta-analysis (J Clin Lipidol 2018) pooled 12 RCTs with 887 participants: at 1–10 g/day for 2–12 months in patients with dyslipidaemia, spirulina lowered total cholesterol by a mean 0.8 mmol/L and by 0.5 mmol/L versus placebo. The effect is smaller than with statins, methodology heterogeneous and risk of bias high. 2019 and Spanish SEA 2022 standards recommend statins as first line in confirmed cardiovascular risk plus lifestyle change (Mediterranean diet, physical activity, smoking cessation). Spirulina is not in international or Spanish guidelines. If spirulina was bought instead of a prescribed statin, discuss with a cardiologist; stopping a statin in confirmed coronary disease multiplies the heart-attack risk.

Sources

Body detoxification and cleansing

Not recommended

Spirulina is a blue-green algae sold as a supplement and often marketed for detox and body cleansing. There is no convincing evidence for this use: good-quality studies do not show that spirulina removes toxins or cleanses the body. The liver and kidneys already clear metabolites and foreign substances, so no special detox product is needed for that. If you have a real health problem, do not use spirulina in place of treatment with proven benefit, because that can mean missing the care you need.

Sources

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Safety

Contraindications

Phenylketonuria (spirulina contains phenylalanine)
Autoimmune disease (rheumatoid arthritis, multiple sclerosis, SLE) – theoretical immune activation
Severe hepatic or renal impairment
Known allergy to cyanobacteria or algae

Serious adverse effects

Acute hepatitis from microcystin-contaminated product (cases described in the USA and Europe)
Chronic arsenic and heavy-metal poisoning with long-term low-quality spirulina
Severe allergic reactions including anaphylaxis

Common adverse effects

Gastrointestinal discomfort, nausea, diarrhoea in the first days
Green discolouration of urine and stool
Headache and mild fever in a Jarisch-Herxheimer-like reaction

PregnancyFDA N

Spirulina safety in human pregnancy has not been studied in RCTs. EFSA has set no safe dose for pregnant women. The main risk is microcystin and heavy-metal contamination, hazardous for fetal development. AEMPS and AESAN advise avoiding supplements without therapeutic indication during pregnancy.

Breastfeeding

Lactation safety has not been studied in RCTs. Microcystins and heavy metals from contaminated spirulina can pass into human milk. Spirulina is not justified during lactation.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Frequently asked

What is Spirulina used for?

Spirulina is evaluated for the following indications with varying evidence strength: Dyslipidemia (evidence tier C), Body detoxification and cleansing (evidence tier D). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Spirulina?

Common side effects of Spirulina (≥ 1 in 100): Gastrointestinal discomfort, nausea, diarrhoea in the first days, Green discolouration of urine and stool, Headache and mild fever in a Jarisch-Herxheimer-like reaction. See the Safety section for uncommon and serious reactions.

Is Spirulina safe during pregnancy?

FDA category N. Spirulina safety in human pregnancy has not been studied in RCTs. EFSA has set no safe dose for pregnant women. The main risk is microcystin and heavy-metal contamination, hazardous for fetal development. AEMPS and AESAN advise avoiding supplements without therapeutic indication during pregnancy.

Is Spirulina compatible with breastfeeding?

Lactation safety has not been studied in RCTs. Microcystins and heavy metals from contaminated spirulina can pass into human milk. Spirulina is not justified during lactation.

Who should not take Spirulina?

Spirulina is contraindicated in: Phenylketonuria (spirulina contains phenylalanine); Autoimmune disease (rheumatoid arthritis, multiple sclerosis, SLE) – theoretical immune activation; Severe hepatic or renal impairment; Known allergy to cyanobacteria or algae. Full list in the Safety section.

Mechanism of action

Safety

Contraindications

Phenylketonuria (spirulina contains phenylalanine)
Autoimmune disease (rheumatoid arthritis, multiple sclerosis, SLE) – theoretical immune activation
Severe hepatic or renal impairment
Known allergy to cyanobacteria or algae

Serious adverse effects

Acute hepatitis from microcystin-contaminated product (cases described in the USA and Europe)
Chronic arsenic and heavy-metal poisoning with long-term low-quality spirulina
Severe allergic reactions including anaphylaxis

Common adverse effects

Gastrointestinal discomfort, nausea, diarrhoea in the first days
Green discolouration of urine and stool
Headache and mild fever in a Jarisch-Herxheimer-like reaction

PregnancyFDA N

Breastfeeding

Lactation safety has not been studied in RCTs. Microcystins and heavy metals from contaminated spirulina can pass into human milk. Spirulina is not justified during lactation.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Frequently asked

What is Spirulina used for?

What are the side effects of Spirulina?

Is Spirulina safe during pregnancy?

Is Spirulina compatible with breastfeeding?

Lactation safety has not been studied in RCTs. Microcystins and heavy metals from contaminated spirulina can pass into human milk. Spirulina is not justified during lactation.

Who should not take Spirulina?