Spirulina & Chlorella
Spirulina and chlorella: how they differ, what meta-analyses show for blood pressure and cholesterol, and quality problems found in spirulina supplements.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Overview and identity
Spirulina and chlorella are both sold as "algae" supplements, but they are different organisms. GBIF classifies Arthrospira platensis (the species commonly sold as spirulina) among Cyanobacteria, and Chlorella vulgaris as a green alga (Chlorophyta). [1] Labels may say "spirulina" for Arthrospira products; check the Latin name. Do not assume results for one apply to the other.What the research shows
A 2025 systematic review and meta-analysis of randomized trials found 12 studies of chlorella and 9 of spirulina on cardiovascular risk factors. [2]| Use | What the review found | Strength of evidence |
|---|---|---|
| Chlorella: blood pressure and blood fats | Neutral effect. [2] | Neutral |
| Spirulina: diastolic blood pressure | A small, statistically significant reduction (-0.42, 95% CI -0.81 to -0.02); the authors say the size is small and of uncertain clinical significance. [2] | Small, uncertain |
| Spirulina: cholesterol and blood fats | No significant effect, though a trend toward lower total cholesterol. [2] | No clear effect |
| Overall | Authors call for further randomized trials. Two authors list an affiliation with a company (Sea4Us SA). [2] | Limited |
Other claims (detox, energy, immunity, weight loss) are not supported by sources we have read, so we make no claim.
Quality problems
A study of spirulina supplements sold in Slovenia found that 86.7% of declarations about elemental content were inappropriate, that additives caused significant variation in nutrient content and sometimes lower quality, and that iron was high on paper but present mostly in a form with much lower bioavailability. The authors concluded stricter control is needed. [3] This is a single national market study, so it does not describe every product. See Quality.Safety
We did not find a regulator or NIH page for spirulina or chlorella that we could read, so we do not list specific interactions or doses. Ask a pharmacist, especially if you take medicines or have a medical condition, and be cautious with products from an unknown source.Frequently asked questions
Is spirulina the same as chlorella?
No. They are different organisms with different research. [1][2]
Does spirulina lower blood pressure?
A 2025 meta-analysis found a small reduction in diastolic pressure of uncertain clinical significance. [2]
References
- GBIF Secretariat. GBIF Backbone Taxonomy. Names checked 2026-10-22 through the GBIF species match service.
- Pinto-Leite M, et al. The Role of Chlorella and Spirulina as Adjuvants of Cardiovascular Risk Factor Control: A Systematic Review and Meta-Analysis of Randomised Controlled Trials. Nutrients. 2025;17(6):943. PubMed 40289965. Two authors list an affiliation with Sea4Us SA, a company, in the paper.
- Masten Rutar J, et al. Nutritional Quality and Safety of the Spirulina Dietary Supplements Sold on the Slovenian Market. Foods. 2022;11(6):849. PubMed 35327271.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.