Main content Blue-Green Algae

Blue-Green Algae

Uses

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For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

This supplement has been used in connection with the following health conditions:

Used for	Why
1 Star Obesity Refer to label instructions	Blue-green algae, or spirulina, is a rich source of protein, vitamins, minerals, and essential fatty acids. It has been promoted as a weight-loss aid, but this claim has not been proven by research. Blue-green algae, or spirulina, is a rich source of protein, vitamins, minerals, and essential fatty acids. In one double-blind trial, overweight people who took 2.8 grams of spirulina three times per day for four weeks experienced only small and statistically nonsignificant weight loss.² Thus, although spirulina has been promoted as a weight-loss aid, the scientific evidence supporting its use for this purpose is weak.

Used for

Why

1 Star

Obesity

Refer to label instructions

Blue-green algae, or spirulina, is a rich source of protein, vitamins, minerals, and essential fatty acids. It has been promoted as a weight-loss aid, but this claim has not been proven by research.

Blue-green algae, or spirulina, is a rich source of protein, vitamins, minerals, and essential fatty acids. In one double-blind trial, overweight people who took 2.8 grams of spirulina three times per day for four weeks experienced only small and statistically nonsignificant weight loss.² Thus, although spirulina has been promoted as a weight-loss aid, the scientific evidence supporting its use for this purpose is weak.

How It Works

How to Use It

Blue-green algae can be taken as a powder or as flakes, capsules, or tablets. The typical manufacturer’s recommended intake is 2,000–3,000 mg per day divided throughout the day. However, typical amounts shown to have helpful properties in animal studies would be equivalent to 34 grams per day or more, for a 150-pound human.

Where to Find It

Blue-green algae grow in some lakes, particularly those rich in salts, in Central and South America, and Africa. They are also grown in outdoor tanks specifically to be harvested for nutritional supplements.

Possible Deficiencies

As it is not an essential nutrient, blue-green algae is not associated with a deficiency state. However, people who do not consume several servings of vegetables per day could benefit from the Reference carotenoids and other nutrients in blue-green algae. Since it is a complete protein, it can be used in place of some of the protein in a healthy diet. However, very large amounts are required to provide significant quantities of these nutrients from blue-green algae.

Interactions

Interactions with Supplements, Foods, & Other Compounds

At the time of writing, there were no well-known supplement or food interactions with this supplement.

Interactions with Medicines

As of the last update, no reported interactions between this supplement and medicines. It is possible that unknown interactions exist. If you take medication, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Few side effects have been reported from the ingestion of blue-green algae. However, as blue-green algae can accumulate heavy metals from contaminated water, consuming blue-green algae could increase the body’s load of lead, mercury, and cadmium,³ though noncontaminated blue-green algae have been identified.⁴ Another popular species of blue-green algae, Aphanizomenon flos-aquae, has been found to produce toxins.⁵ A few reports also describe allergic reactions to blue-green algae. Animal studies have found spirulina to be safe during Reference pregnancy.⁶ ^{, 7} ^{, 8}

There is one case report of a man who developed liver damage while taking spirulina.⁹ As he was also talking three prescription medications, it is not clear whether the spirulina caused or contributed to the liver injury.

Related Information

Reference Blue-Green Algae for Weight Control

References

1. Dillon JC, Phuc AP, Dubacq JP. Nutritional value of the alga Spirulina. World Rev Nutr Diet 1995;77:32-46.

2. Becher EW, Jakober B, Luft D, et al.Clinical and biochemical evaluations of the alga spirulina with regard to its application inthe treatment of obesity. A double-blind cross-over study. Nutr Rep Intl1986;33:565–73.

3. Johnson PE, Shubert LE. Accumulation of mercury and other elements by spirulina (cyanophyceae). Nutr Rep Int 1986;34:1063–70.

4. Slotton DG, Goldman CR, Franke A. Commercially grown spirulina found to contain low levels of mercury and lead. Nutr Rep Int 1989;40:1165–72.

5. Elder GH, Hunter PR, Codd GA. Hazardous freshwater cyanobacteria (blue-green algae). Lancet 1993;341:1519–20 [letter].

6. Salazar M, Chamorro GA, Salazar S, et al. Effect of Spirulina maxima consumption on reproduction and peri- and postnatal development in rats. Food Chem Toxicol 1996;34:353–9.

7. Kapoor R, Mehta U. Effect of supplementation of blue green alga (Spirulina) on outcome of pregnancy in rats. Plant Foods Hum Nutr 1993;43:29–35.

8. Chamorro G, Salazar M. Teratogenic study of Spirulina in mice. Arch Latinoam Nutr 1990;40:86–94 [in Spanish].

9. Iwasa M, Yamamoto M, Tanaka Y, et al. Spirulina-associated hepatotoxicity. Am J Gastroenterol 2002;97:3212–3. [Letter]

Last Review: 11-07-2012

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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2013.

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