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The Benefits of Blue-Green Algae Tablets

author image Diana Kaniecki
Diana Kaniecki has been writing health-related articles since 1991. Her work has appeared in peer-reviewed health journals including the "American Journal of Cardiology," "Chest" and "Pharmacoeconomics." She also develops health technology products for wellness and chronic illness self-management. Kaniecki received her Doctor of Clinical Pharmacy from St. Johns University.
The Benefits of Blue-Green Algae Tablets
Teal colored capsules. Photo Credit: Jordan McCullough/iStock/Getty Images

Blue-green algae is a group of about 1,500 species of algae that are known for being rich sources of protein. These plants contain carotenoids, vitamins, minerals and essential fatty acids as well. It has long been harvested in Mexico and the Sahara desert for its medicinal properties. Presently, there is insufficient scientific data from human studies to support the efficacy of blue-green algae for any condition. Consult your healthcare provider before using blue-green algae medicinally.

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Identification and Dosage

Spirulina is the name most often used to identify the whole group of edible blue-green algae, even though it represents only a few of the many blue-green algae species. It is available in several oral dosage forms, and is most commonly used as 500 mg or 750 mg tablets. The usual daily dose of blue-green algae is 2,000 to 3,000 mg, taken in divided doses during the day. Research studies have used spirulina in doses of 1 to 10 g per day.


Blue-green algae has various purported benefits, including immune system stimulation, lowering cholesterol and antiviral and anticancer effects. It is also purported to manage obesity. Blue-green algae contains antioxidants, including zeaxanthin, which may help to strengthen the retina of the eye and possibly prevent macular degeneration, a condition that can seriously impair or destroy vision. Spirulina may also help to prevent development of kidney stones caused by chemicals called oxalates.


Preliminary research on the benefits to overweight individuals of taking spirulina for four weeks showed only small and insignificant amounts of weight loss. Results from some early human and animal trials have shown that spirulina lowered cholesterol levels significantly more than placebo, or inactive sugar pills. Human research studies in diabetics have also shown that spirulina may have some effectiveness in lowering blood sugar. However, more human studies are needed to evaluate spirulina's usefulness for these and other uses.


According to the, blue-green algae is generally well tolerated and causes few side effects. It may rarely cause allergic reactions, however. Also, blue-green algae may be contaminated with environmental water pollutants such as lead, mercury, and cadmium, which are metals that can be harmful to human health when ingested. Spirulina should be avoided during pregnancy and breastfeeding.

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