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Spirulina is a non-toxic blue-green algae. It is a source of phycocyanobilin. Preliminary evidence suggests spirulina is remarkably potent at protecting the brain and reducing liver fat.

Our evidence-based analysis on spirulina features 210 unique references to scientific papers.

Research analysis led by and reviewed by the Examine team.
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Summary of Spirulina

Primary information, health benefits, side effects, usage, and other important details

Spirulina is a blue-green algae. It is an easily produced, non-toxic species of Arthrospira bacteria.

Spirulina is often used as a vegan source of protein and vitamin B12. It is between 55-70% protein, but studies suggest it is a subpar source of B12, as the vitamin is not absorbed well after ingestion.

Human evidence suggests that spirulina can improve lipid and glucose metabolism, while also reducing liver fat and protecting the heart. Animal studies are very promising as well, as spirulina has been shown to be of similar potency as commonly used reference drugs, when it comes to neurological disorders. These effects also extend to arthritis and immunology.

Spirulina has a few active components. The main ingredient is called phycocyanobilin, which makes up about 1% of spirulina. This compound mimics the body’s bilirubin compound, in order to inhibit an enzyme complex called Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase. By inhibiting NADPH oxidase, spirulina provides potent anti-oxidative and anti-inflammatory effects.

The neurological effects of spirulina need more human evidence. Based on animal evidence, spirulina appears to be a promising anti-oxidant and supplement for metabolic issues.

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How to Take

Recommended dosage, active amounts, other details

The dose of spirulina used in studies examining its effects vary greatly. In general, 1-8 g per day of spirulina has been shown to have some effect. The specific doses depend on the condition its being used for:

  • For cholesterol, doses in the range of 1-8 g per day may be impactful

  • For muscle performance, doses of 2-7.5 g per day have been used

  • For blood glucose control, very mild effects have been seen with 2 g per day

  • Blood pressure may be affected at doses of 3.5-4.5 g per day

  • Effects for fatty liver have been seen at doses of 4.5 g per day

Spirulina is about 20% C-phycocyanin by weight, and about 1% phycocyanobilin by weight. The dosage range of 200mg/kg C-phycocyanin (1g/kg spirulina) converted to human equivalent doses from rats is approximately:

  • 11.0g for a 150lb person

  • 14.5g for a 200lb person

  • 18.2g for a 250lb person

Further research is needed to determine whether spirulina should be taken once a day, or in smaller doses, multiple times per day.

It is not recommended to exceed the highest dose mentioned above, as no clear benefits have been noted beyond that level.

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Human Effect Matrix

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The Human Effect Matrix summarizes human studies to tell you what effects Spirulina has on your body, how much evidence there is, and how strong these effects are.

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Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-b Notable Very High See all 3 studies
Although there is no reference drug to compare the effects of Spirulina against, the decrease in lipid peroxidation as assessed by serum MDA is quite notable and is likely stronger than other supplements. A comparative study would be needed
grade-b Notable Moderate See all 13 studies
In populations with metabolic syndrome or related morbidities (diabetes, hyperlipidemia, hypertension, etc.) spirulina in a variety of doses between 1-8g daily is able to reduce triglycerides up to 10-15%.
grade-b Minor Very High See all 11 studies
A positive influence of spirulina on HDL-C appears to be present, but the magnitude of benefit is not overly remarkable and varies depending on the disease state (with states associated with fatty liver having a much greater increase in HDL-C seen with spirulina)
grade-b Minor Very High See all 11 studies
Degree of efficacy seems variable and correlated with disease state (more drastic improvements when LDL-C is much higher) but currently does not appear to be overly remarkable unless fatty liver exists.
grade-b Minor High See all 3 studies
Studies currently assessing the effects of spirulina on muscular endurance are too hetereogeneous to properly assess potency thereof. However, a positive effect does appear to exist
grade-b Minor Very High See all 11 studies
Reductions in cholesterol seen are positive, but not overly remarkable
grade-c Strong - See study
The lone study suggests that spirulina is strongly effective in controlling allergies, with the symptoms of nasal discharge, sneezing, nasal congestion and itching being time-dependently reduced. According to self-reports, more than twice as many subjects in the spirulina group reported more than a 2-fold increase in satisfaction with treatment.
grade-c Strong - See study
The decrease in nasal congestion seen in the one study was remarkably strong relative to placebo in a model of allergic rhinitus; it is not sure if this applies to other causes of nasal congestion.
grade-c Notable Moderate See all 5 studies
Insufficient evidence to fully evaluate the effects on blood pressure, but given how 6 weeks supplementation reduced both systolic and diastolic in nonhypertensive persons by about 11/6 points it is notable
grade-c Notable Very High See 2 studies
Notable due to mechanisms, but requires studies with reference drugs and more biomarkers measured.
grade-c Notable Moderate See 2 studies
Lone study noted a decrease from 9% to 8% with 2g spirulina, which is somewhat notable but requires more evidence to establish this.
grade-c Notable - See study
Notable as acute power output (leg extension measurement) increased by 20-30% (more efficacy in untrained persons, some efficacy in trained persons) after 8 weeks whereas placebo failed to have an increase. Needs more research to fine-tune the efficacy.
grade-c Notable - See study
The lesions were fully healed in 44% of the 1g spirulina group relative to 7% of the placebo; although no reference drug was used.
grade-c Minor Very High See all 3 studies
Although increases have been noted in glutathione peroxidase and superoxide dismutase, it is difficult to assess potency thereof as there are no active controls and the two studies heterogenous.
grade-c Minor - See study
Somewhat effective, but requires more evidence; no reference drug was used to compare
grade-c Minor Moderate See all 6 studies
Reductions in blood glucose seen are not overly remarkable or noteworthy
grade-c Minor - See study
Nothing remarkable in the one study on fat oxidation rates during exercise.
grade-c Minor Moderate See 2 studies
Some various and uncertain changes in cytokines that are seen as indicators of inflammation; not enough human interventions to draw conclusions.
grade-c Minor - See study
Requires more evidence to establish its potency
grade-c Minor - See study
Although there was some promising evidence, it did not appear overly remarkable and requires further evidence.
grade-c Minor - See study
Minor increase, needs more evidence in a non-aged cohort to assess potency
grade-c - - See study
Currently insufficient evidence to support a change in RBC count.
grade-c - Very High See all 6 studies
Currently not enough evidence to support any significant interaction with weight
grade-d Strong - See study
Although only based on a series of case studies at this moment in time, the reduction of liver fat seen after 3 months was remarkably effective
grade-d Notable High See all 3 studies
Preliminary evidence suggests the reduction of liver enzymes correlates with the degree of liver damage somewhat, and this is notable since the reduction of liver fat seen is strongly effective at this moment in time.
grade-d Notable - See study
NK cell activity against a tumor cell line (K562) increased 40% following a week ingestion of fairly reasonable oral dosing, suggesting that this is a notable increase of possible interest.
grade-d Notable - See study
The increases in mRNA content of natural killer cell content increased 37-55% (NKG2D) and 75% (perforin) which appeared to be dose-dependent, a possibly potent immunostimulatory effect.
grade-d Notable - See study
Notably effective as it trended to outperform Milk Thistle, which is a good reference supplement in regards to a sustained virologic response (not the best comparison, however)
grade-d - - See study
grade-d - - See study
grade-d - - See study
Currently no evidence to support an improvement in fatigue symptoms
grade-d - - See study
grade-d - - See study
grade-d - - See 2 studies
grade-d - - See study
grade-d - - See study
grade-d - - See study
grade-d - - See study
grade-d - - See study
grade-d - - See study
grade-d - - See study
grade-d - - See study

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Frequently Asked Questions and Articles on Spirulina

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Things to Note

Caution Notice

Some users may possess allergies to spirulina (infrequent)

May interact with enzymes of drug metabolism

  • An allergic reaction to spirulina has been reported, although overall frequency of allergic responses or cross-sensitivities are not yet known

  • Preliminary evidence has suggested a reduction in the activities of the enzymes CYP2C6, CYP1A2, and CYP2E1

  • The same evidence has noted an upregulation (increase in activity) for both CYP2B1 and CYP3A1

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Click here to see all 210 references.