What Is the Difference Between Spirulina & Blue-Green Algae?

Spirulina in powder, herb and pill form sit on a white counter.
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Blue-green algae products are popular for weight loss, being taken to lower cholesterol and for cancer prevention. The blue-green species in its natural dried state is used as a food source in some parts of the world. In supplement form, it is used as a nutritional boost. Spirulina is a naturally occurring blue-green algae that is commercially grown in a controlled environment. Another natural blue-green algae, Aphanizomenon flos-aquae (AFA), is grown commercially in the wild, allowing for potential contamination. Blue-green algae are a phylum of bacteria and not true algae. Claims concerning the health benefits of supplemental blue-green algae are not scientifically verified.



Blue-green algae is a group of primitive bacteria, known as cyanobacteria, which exhibit photosynthesis, reports Purdue University plant pathologist, Carole A. Lembi. Within this group is spirulina, a one-celled organism found in fresh waters of alkaline state. Spirulina derives its name from its spiral shape as seen under the microscope. Natural Ways to Health reports that as a single-celled organism it is uniquely large, with sizes equalling 0.5 mm in length, about 100 times larger than other single-celled algae. This unique property makes some cells of spirulina visible to the naked eye.


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In desert conditions, some species of blue-green algae survive when the water source evaporates and temperatures reach 160 degrees F. Spirulina's ability to thrive in waters between 85 to 112 degrees F and in alkalinity from 8 to 11 pH make it a hygienic food source, as other organisms cannot survive in the same conditions, according to Natural Ways to Health. As spirulina grows, the plants bunch together, sticking to one another, allowing for easy harvest. Spirulina also reproduces very fast.



Health benefits, from weight loss to cancer prevention, have been purported for blue-green algae products, according to the University of California Berkeley, which does not endorse the products for these purposes. General nutritive value derived from spirulina includes protein, B vitamins, beta-carotene, several minerals and gamma-linolenic acid. Other purported uses of blue-green algae products are for ADHD, lowering cholesterol, viral infections, fatigue and HIV. Spirulina is being touted as the food of the future because it has the ability to utilize its food source more efficiently than other blue-green algae, leading to a product that delivers more nutrition, reports Natural Ways to Health.



Algae blooms

The University of California at Berkeley reports that equivalent nutrition can be obtained in greater quantities and less expensively from foods than from spirulina. The report goes on to say that AFA, which is grown and harvested in the wild, is often contaminated. AFA is grown commercially in the unique conditions of Upper Klamath Lake, Oregon. According to Memorial Sloan-Kettering Cancer Center, algae products often use both spirulina and AFA, leading to the potential for toxic contamination.



Heavy growth areas of blue-green algae, called blooms, occur in the wild due to fertilizer and waste runoff. This has been associated with toxic events in animals that drink the water, according to Lembi of Purdue. Spirulina apparently contains no toxins in itself; however, many species of blue-green algae may be contaminated with natural toxins called microcystins. Anatoxin is also a contaminant in several blue-green species. Unfortunately, only some states have strict guidelines for limits of microcystins in algae products.



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