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Harmful Effects of Blue-Green Algae

author image Janet Renee, MS, RD
Janet Renee is a clinical dietitian with a special interest in weight management, sports dietetics, medical nutrition therapy and diet trends. She earned her Master of Science in nutrition from the University of Chicago and has contributed to health and wellness magazines, including Prevention, Self, Shape and Cooking Light.
Harmful Effects of Blue-Green Algae
Two spoonfuls of blue-green algae powder and supplements. Photo Credit: joannawnuk/iStock/Getty Images

It's always best to talk it over with your doctor before taking any dietary supplements, including spirulina, the most common blue-green algae. While taking spirulina may have benefits, it also has potential drawbacks.

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Blue-Green Algae Nutrition

Blue-green algae is a large group of saltwater and freshwater organisms that possess a versatile nutrition profile. Spirulina, for example, contains the minerals zinc, copper, iron, manganese and selenium, as well as vitamin E, B complex vitamins and the essential fat gamma linolenic acid. Some people blue-green algae as a vegetarian protein source. According to the University of Maryland Medical Center, spirulina is composed of 62 percent amino acids -- building blocks of protein,

Microcystin Contamination

Blue-green algae can be contaminated by toxins called microcystins that can cause kidney failure, liver toxicity and nervous system toxicity, according to Memorial Sloan Kettering Cancer Center. A study published in the journal Environmental Health Perspectives in May 2000 found that 72 percent of blue-green algae supplements tested contained microcystin levels higher than the regulatory limit. It's crucial for you to choose products that are labeled certified free of microcystin contamination.

Rare but Life-Threatening Effect

The June 2008 edition of the journal Phytomedicine included a case report of a spirulina supplement causing rhabdomyolysis. This rare condition is characterized by muscle tissue breaking down and leaking into the bloodstream, which can have damaging effects. The 28-year-old man in the case report had taken spirulina for one month before developing rhabdomyolysis, and his symptoms resolved after he stopped taking the supplement, according to the MSKCC.

Harmful Effect on Newborns

It may not be safe to take blue-green algae while you are pregnant. While doctors commonly recommend prenatal supplements to ensure you have enough nutrients for yourself and your baby, there is a risk of you or your baby getting too much of certain nutrients if you add a blue-green algae supplement. The European Journal of Clinical Pharmacology published a case report in February 2012 of chronic maternal consumption of spirulina supplements causing hypercalcemia in a newborn. Hypercalcemia is when calcium levels are much higher than normal, which can negatively affect organs.

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