Spirulina, a nutrient-dense type of blue-green algae, is often touted for its rich concentrations of vitamins, minerals and antioxidants. While research has determined a number of potential health applications for spirulina, the risks of this supplement should not be overlooked. Spirulina has often been promoted for everything from lowering cholesterol and increasing energy to treating premenstrual syndrome and depression. It should be noted, however, that scientific proof backing these uses is lacking.
Exceptional Nutritional Value
One of the most notable advantages of spirulina is its complete nutritional profile. University of Maryland Medical Center notes that this unique food is rich in B-complex vitamins, zinc, vitamin E, beta carotene, copper, selenium, iron and essential fatty acids. In addition, spirulina is about 62 percent protein by weight. The nutritional completeness of spirulina makes it a functional food with multivitaminlike properties. Spirulina can be useful in avoiding nutritional deficiencies and promoting overall good health.
Immune-Boosting and Allergy-Protecting
Spirulina may help increase the production of antibodies -- substances that help fight off infections and chronic diseases. UMMC notes, however, that these effects have not been tested in humans. A study published in 2005 in the "Journal of Medicinal Food" found that spirulina supplementation was able to help reduce the effects of allergic rhinitis -- allergies of the nose, usually in response to dust, pollen or dander. According to UMMC, in test tube trials, spirulina was also effective in promoting the growth of good gut bacteria, known as probiotics.
Watch Out for Toxins
The most well-known drawback of spirulina is its potential to be contaminated with toxins known as micocystins, which can absorb heavy metals. As nutrition expert Michael Greger explains, although spirulina itself is not a toxin-producing algae, the harvesting process can inadvertently include small amounts of other algae that do produce toxins. Greger notes that this explains many tests that have found various spirulina supplements to be contaminated with toxins. UMMC, however, notes that spirulina can only absorb heavy metals from the water in which it's grown; therefore, it is important to purchase it from a trusted manufacturer.
Safety and Considerations
MedlinePlus rates spirulina supplements as "possibly safe" for most people, so long as they are free of microcystins, toxic metals and harmful bacteria. Because spirulina stimulates the functioning of the immune system and can increase the symptoms of autoimmune diseases, MedlinePlus recommends those with diseases such as multiple sclerosis, lupus and rheumatoid arthritis avoid it. Pregnant and breast-feeding women should avoid spirulina to be safe, and because children are more sensitive to contaminants, it's even more important that they consume a product free of contaminants.