What Is Spirulina?

Spirulina may help lower cholesterol

Spirulina tablets, capsules, powder, and juice

Verywell / Anastasia Tretiak

Spirulina is a type of blue-green algae that contains a number of nutrients, including B vitamins, beta-carotene, and vitamin E. Spirulina also contains antioxidants, minerals, chlorophyll, and phycocyanobilin and is commonly used as a source of vegan protein.

What Is Spirulina Used For?

Among proponents, spirulina has been used to support a number of health conditions, including fatigue, high cholesterol, high triglycerides, and viral infections.

Purported spirulina benefits also include weight loss, increased energy, and stimulation of the immune system.

To date, few human studies have explored spirulina's health benefits. However, preliminary studies suggest that spirulina may hold promise for the following conditions.

High Cholesterol

Spirulina holds some promise for lipid disorders such as high cholesterol or high triglycerides, according to a study published in the Annals of Nutrition and Metabolism. For the study, healthy, older adults consumed spirulina or a placebo. After four months, spirulina was associated with significant reductions in cholesterol.  

Allergies

Spirulina holds some promise in the treatment of allergic rhinitis (nasal allergies), according to a review published in 2009. Indeed, a previously published study of people with allergic rhinitis found several benefits for spirulina consumption, including improvement in symptoms like nasal discharge, sneezing, congestion, and itching.

Diabetes

In a 2008 study involving 37 people with type 2 diabetes, researchers found that those assigned to 12 weeks of spirulina supplementation experienced a significant reduction in blood-fat levels. Spirulina benefits also included a decrease in inflammation and, for some people, a decrease in blood pressure and cholesterol.

In another small study, 15 people diagnosed with diabetes who were not using insulin took 2 grams of spirulina a day in supplement form for two months. They didn’t change any other factors of their diet or lifestyle. At the end of the study period, the participants saw a reduction in blood sugar, cholesterol, and triglyceride levels.

Oral Cancer

Spirulina may offer some protection against oral cancer, according to one small study of tobacco chewers with precancerous oral lesions. For 12 months, study members took either a daily dose of spirulina or a placebo. By the study's end, the lesions cleared up in 20 of the 44 participants who had consumed spirulina (compared to three of the 43 participants who had been assigned to the placebo group).

Possible Side Effects

Although few adverse effects are associated with the use of spirulina, consuming spirulina may cause headaches, allergic reactions, muscle pain, sweating, and insomnia in some cases. People with allergies to seafood, seaweed, and other sea vegetables should avoid spirulina.

If you have a thyroid condition, an autoimmune disorder, gout, kidney stones, phenylketonuria, or are pregnant or nursing, spirulina may not be appropriate for you. You should check with your healthcare provider before taking it.

It's possible that spirulina grown in the wild can absorb toxins from water, such as microcystins (known to cause severe liver damage), pollutants, and heavy metals. Most spirulina sold in the United States is grown in laboratories.

As with all supplements, it's important to consult your healthcare provider before using spirulina to discuss whether it's appropriate for you and whether it can be consumed in combination with other medications and/ or supplements you may be taking.

Spirulina powder
Verywell / Anastasia Tretiak

Dosage and Preparation

There is not enough scientific data to provide a recommended dose of spirulina. Various doses of spirulina have been used in research.

For example, in several studies examining the benefits of spirulina for high cholesterol, doses of 1-8 grams daily for four weeks to six months has been used. To learn about its effects on hypertension, one study administered a dose of 4.5 grams of spirulina blue-green algae daily for six weeks. Another study of type 2 diabetes patients administered a product containing 1 gram of spirulina twice daily for two months.

The appropriate dose for you may depend on factors including your age, gender, and medical history. Speak to your healthcare provider to get personalized advice.

What to Look For

Spirulina is often sold in powder form, but it's also available in capsules, tablets, and juices. The powder is sometimes added to smoothies.

Although there are a large number of blue-green algae species commonly referred to as "spirulina," most spirulina supplements contain Aphanizomenon flos-aquae, Spirulina maxima, and/or Spirulina platensis.

As with all supplements, it is important to examine the "Supplement Facts" label on any product that you buy. This label will contain vital information, including the amount of active ingredients per serving and any other ingredients that might be in the product.

Lastly, look for a product that contains a seal of approval from a third-party organization that provides quality testing. These organizations include U.S. Pharmacopeia, ConsumerLab.com, and NSF International. A seal of approval from one of these organizations does not guarantee the product's safety or effectiveness, but it does provide assurance that the product was properly manufactured, contains the ingredients listed on the label, and does not contain harmful levels of contaminants.

Frequently Asked Questions

  • What are the benefits of spirulina?

    Spirulina is a nutrient-dense blue-green algae used as a nutritional supplement. It is purported to help reduce fatigue and boost energy, lower cholesterol and triglyceride levels, stimulate the immune system, fight viral infections, and aid in weight loss.

  • What are the side effects of taking spirulina?

    Spirulina rarely causes side effects, but the potential side effects include headaches, muscle pain, sweating, and insomnia. Some people can be allergic to spirulina and may experience an allergic reaction.

  • Who should not take spirulina?

    People who should not take spirulina include those with: 

    • Allergies to seafood, seaweed, and other sea vegetables
    • Autoimmune disorders
    • Gout
    • Kidney stones
    • Phenylketonuria (PKU)

    In addition, women who are pregnant or nursing should avoid spirulina supplements as their effect on fetal and infant health is unclear.

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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Park HJ, Lee YJ, Ryu HK, Kim MH, Chung HW, Kim WY. A randomized double-blind, placebo-controlled study to establish the effects of spirulina in elderly Koreans. Ann Nutr Metab. 2008;52(4):322-8. doi:10.1159/000151486

  2. Man LX. Complementary and alternative medicine for allergic rhinitis. Curr Opin Otolaryngol Head Neck Surg. 2009 17(3):226-31. doi:10.1097/MOO.0b013e3283295791


  3. Cingi C, Conk-Dalay M, Cakli H, Bal C. The effects of spirulina on allergic rhinitis. Eur Arch Otorhinolaryngol. 2008 265(10):1219-23. doi:10.1007/s00405-008-0642-8

  4. Lee EH, Park JE, Choi YJ, Huh KB, Kim WY. A randomized study to establish the effects of spirulina in type 2 diabetes mellitus patients. Nutr Res Pract. 2008 2(4):295-300. doi:10.4162/nrp.2008.2.4.295

  5. Mani UV, Desai S, Iyer U. Studies on the Long-Term Effect of Spirulina Supplementation on Serum Lipid Profile and Glycated Proteins in NIDDM Patients. Journal of Nutraceuticals, Functional & Medical Foods, 2000;2:3, 25-32. doi:10.1300/J133v02n03_03

  6. Mathew B, Sankaranarayanan R, Nair PP, et al. Evaluation of chemoprevention of oral cancer with Spirulina fusiformis. Nutr Cancer. 1995;24(2):197-202. doi:10.1080/01635589509514407

  7. Torres-duran PV, Ferreira-hermosillo A, Juarez-oropeza MA. Antihyperlipemic and antihypertensive effects of Spirulina maxima in an open sample of Mexican population: a preliminary report. Lipids Health Dis. 2007;6:33. doi:10.1186/1476-511X-6-33

  8. U. V. Mani, S. Desai & U. Iyer (2000) Studies on the Long-Term Effect of Spirulina Supplementation on Serum Lipid Profile and Glycated Proteins in NIDDM Patients. Journal of Nutraceuticals, Functional & Medical Foods, 2:3, 25-32. doi:10.1300/J133v02n03_03


Additional Reading
  • Miczke A, Szulińska M, Hansdorfer-Korzon R, et al. Effects of spirulina consumption on body weight, blood pressure, and endothelial function in overweight hypertensive Caucasians: a double-blind, placebo-controlled, randomized trial. Eur Rev Med Pharmacol Sci. 2016;20(1):150-6.