Also indexed as: Spirulina

What does it do ? Blue-green algae, of which spirulina is a well-known example, is a group of 1,500 species of microscopic aquatic plants. The two most common species used for human consumption are Spirulina maxima and Spirulina platensis. Spirulina is particularly rich in protein and also contains carotenoids, vitamins, minerals, and essential fatty acids, though its vitamin B12 content does not appear to be readily usable by people. Most health benefits to humans claimed for spirulina and other blue-green algae supplementation come from anecdotes and not scientific research. Test tube and animal studies have demonstrated several properties of large amounts of spirulina or spirulina extracts, including antioxidant, antiviral, anticancer, anti-allergy, immune-enhancing, liver-protecting, blood vessel–relaxing, and blood lipid–lowering effects.

One controlled human study found that Spirulina fusiformis reversed oral leukoplakia (pre-cancerous lesions of the mouth) in 45% of the group given 1 gram per day for one year, compared with only 7% of the group receiving placebo. Another small, controlled study found that overweight individuals taking 8.4 grams per day of spirulina lost an average of three pounds in four weeks compared with 1.5 pounds when taking placebo, though this difference was not significant and no effects on blood pressure or serum cholesterol were observed. A later controlled but un-blinded trial found a small cholesterol-lowering effect when 4.2 grams spirulina per day were taken for eight weeks, but serum triglycerides, blood pressure, and body weight were unchanged.

Where is it found ? Blue-green algae grows in some lakes, particularly those rich in salts, in Central and South America and Africa. It is also grown in outdoor tanks specifically to be harvested for nutritional supplements.

Blue-green algae has been used in connection with the following conditions (refer to the individual health concern for complete information):

Who is likely to be deficient ? As it is not an essential nutrient, blue-green algae is not associated with a deficiency state. However, individuals who do not consume several servings of vegetables per day could benefit from the 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.

How much is usually taken ? 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.

Are there any side effects or interactions ? No side effects have been reported with blue-green algae. However, as blue-green algae can accumulate heavy metals from contaminated water, consuming blue-green algae from such areas can increase the body’s load of lead, mercury, and cadmium, though noncontaminated blue-green algae has been identified. Samples of spirulina have also been found to be contaminated with animal hairs and insect fragments, and another popular species, Aphanizomenon flos-aquae, has been found to produce toxins. A few reports also describe allergic reactions to blue-green algae. Animal studies have found spirulina to be safe during pregnancy.
At the time of writing, there were no well-known drug interactions with blue-green algae.