Spirulina is a type of blue-green algae that lives in large alkaline freshwater lake or subtropical and tropical sea with a high salt content. In the U.S., spirulina is marketed as a dietary supplement. Spirulina supplement comes in tablets, powders and flakes. Each supplement may contain one or more spirulina species, with Spirulina maxima and Spirulina platensis being the most popular. The species are not always identified on the supplement labels. Most of the spirulina species on the U.S. market are cultured species, as opposed to wild ones.
Nutrition Values
Spirulina are often touted for its high protein content because 62 percent of the dry weight is protein. Better yet, the proteins in spirulina are high-quality proteins that provide all of the necessary amino acids humans need. However, the National Institutes of Health says that the proteins in spirulina are no better than those in milk, meat and fish and can cost 30 times as much for the same weight. Spirulina is also rich in vitamins such as B vitamins and vitamin E, and minerals such as iron, zinc, manganese, copper and selenium.
Health Benefits
Spirulina may have immune-enhancing properties. In cultured tubes and animal studies, spirulina stimulates immune cells, prevents the release of allergy-causing chemical histamine, blocks the entry of viruses such as HIV and herpes into the cells and promotes the growth of beneficial bacteria, such as Lactobacillus acidophilus, in the gut. But the University of Maryland Medical Center cautions that none of these benefits has been validated in human studies, although it is used to treat diabetes, depression, fatigue, high cholesterol, heart diseases, attention-deficit disorder, memory problems and premenstrual syndrome.
Side Effects
Cultured uncontaminated spirulina is safe for most people, states the NIH. Natural spirulina, on the other hand, is often contaminated with heavy metals, bacteria and microcystin, a toxin secreted by bacteria. Contaminated spirulina can cause liver damage, rapid heartbeat, shock and death. Choose spirulina that has been tested to be free of contaminants. Because spirulina may stimulate the immune system, you should not take it if you have autoimmune diseases such as lupus, multiple sclerosis and rheumatoid arthritis.
Bottom Line
Uncontaminated spirulina can add nutrients such as vitamins, minerals and proteins to your diet but at a higher cost than many other foods with similar nutrition benefits. Take the health claims surrounding spirulina with a grain of salt because most of the benefits have not been substantiated with human studies. Although spirulina is often promoted as a source of vitamin B-12 for vegans, a review published in "Experimental Biology and Medicine" in 2007 suggests that spirulina contains a form of vitamin B-12 that is not active in humans and should not be used as a dietary source for vitamin B-12.
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