Written by Karen Pilkington and the CAM-Cancer Consortium.
Updated February 28, 2017

Spirulina (blue-green algae)

Does it work?

Systematic reviews, meta-analyses

No systematic reviews of spirulina have been published.

Narrative reviews

One review concluded that spirulina species are capable of inhibiting carcinogenesis due to anti-oxidant properties.1

Clinical trials

A clinical trial of 1g/day of Spirulina fusiformis for chemoprevention of oral cancer was reported in 1995.5 The trial was conducted over the course of 12 months in pan tobacco chewers in Kerala, India who were suffering from oral leucoplakia (a pre-cancerous condition). Complete regression of lesions was observed in 45% (20 of 44 subjects) whose diet was supplemented with spirulina. This compared favourably with those receiving placebo: only 3 of 43 (7%) showed a complete regression in lesions (p < 0.0001). The response appeared to be greater in those with homogeneous lesions. Increased serum concentrations of retinol or beta-carotene were not observed nor was toxicity reported. Sixty people received the spirulina but it appears that the control group was a group who had been randomised to the placebo arm of another study and there were some differences between groups at baseline. Assessment of response was carried out by a physician and a dentist who were unaware of the allocated treatment group but it is unclear to what extent the spirulina and placebo capsules were well-matched. Only the results from those completing the study were included (44 and 43 respectively) in the final analysis. Muscular pain and headaches were reported by 7 and 5 patients taking spirulina and no adverse events were reported by those in the placebo group.

A spirulina product, which apparently has ‘enhanced activity’, was used in a pilot study in the USA in 10 healthy individuals.6 After 7 days of the supplement (400mg per day), increased cytotoxic activity of natural killer cells was observed. A separate placebo-controlled study was also conducted. This study involved 11 healthy Danish participants who were randomised to receive 200mg spirulina, 400mg spirulina or placebo daily each for one week with 3.5 week washout periods between treatments.6 Enhanced natural killer cell activity was again reported after 7 days treatment. Increased T-cell proliferation and interferon production has also been reported in studies in humans.10,11 These studies all suffer from very small numbers of participants (maximum of 12) and were conducted in healthy subjects, therefore the results can only be considered as preliminary.

Citation Karen Pilkington, CAM-Cancer Consortium. Spirulina (blue-green algae) [online document]. http://ws.cam-cancer.org/The-Summaries/Herbal-products/Spirulina-blue-green-algae. February 28, 2017.


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