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

Spirulina (blue-green algae)

Abstract and key points

  • Spirulina are species of blue-green algae used in food colouring.
  • Evidence of effectiveness in cancer is extremely limited.
  • Few serious adverse effects have been reported with products guaranteed to be free from contamination with microcystins.

Spirulina refers to various species of blue-green algae found naturally in lakes and grown commercially.

It is used as a food colouring and is taken orally as a nutritional supplement in tablet, capsule or dried powder form.

It is claimed to have immune-stimulating effects and to be beneficial in a wide range of diseases including cardiovascular disease, diabetes, viral infections and cancer.

Effects on the immune system have been observed in pre-clinical studies and small trials in healthy volunteers and possible protective effects against chemotherapy toxicity have been reported in animal models. One small clinical trial in leukoplakia reported better response (improvement of lesions) to a year’s treatment with spirulina than to placebo.

Few adverse effects have been reported with spirulina products. Some blue-algae products have been found to be contaminated with hepatotoxic microcystins and will not be as safe as pure spirulina supplements.

Evidence of beneficial effects in cancer is extremely limited but spirulina is generally well-tolerated. Reliable evidence on safety in pregnancy and breast-feeding is not available.

Read about the regulation, supervision and reimbursement of herbal medicine at NAFKAMs website CAM Regulation.


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

Document history

Assessed as up to date in January 2015 by Barbara Wider.
Assessed as up to date in January 2015 by Barbara Wider.
Summary first published in April 2013, authored by Karen Pilkington.


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