What Does Spirulina Do to the Body? Benefits and Side Effects

  • Medical Reviewer: Dany Paul Baby, MD
Medically Reviewed on 7/29/2022

What is spirulina? 

Spirulina is a cyanobacterium, also known as blue-green algae. The benefits of spirulina include that it is anti-inflammatory and side effects may include exposure to harmful microorganisms and radioactive metals.
Spirulina is a cyanobacterium, also known as blue-green algae. The benefits of spirulina include that it is anti-inflammatory and side effects may include exposure to harmful microorganisms and radioactive metals.

Spirulina is an alga that humans consume all over the world. Research indicates that it was even eaten in the ancient Aztec civilization. 

For most people, spirulina is considered completely safe to consume. It’s a healthy source of necessary nutrients. It may also have a number of health benefits, but the overall effects are still uncertain. We need more research to understand all of the ways that consuming spirulina will affect your body. 

Spirulina is a cyanobacterium, also known as blue-green algae. It’s a single-celled organism that has spiraling filaments on its exterior. Its name is inspired by these filaments. 

It grows in fresh and saltwater all around the world and does best in warm climates.

NASA first made spirulina popular when it considered using it as a food source for astronauts in 1988.   

Since then, spirulina has been sold in health food stores and online for years as a dietary supplement. It can be dried or freeze-dried and turned into flakes, a powder, or a pill. It’s sometimes added to health drinks

There are many different species of spirulina. The two main types that NASA experimented with are the most popular today. This includes Spirulina maxima and Spirulina plantensis.  

Most of the spirulina that you can buy in the U.S. is grown in a lab. Mexico is the main supplier of S. maxima, and California is the main supplier of S. plantensis.    

What nutrients are in spirulina? 

Spirulina contains a number of healthy ingredients, including high levels of protein. In fact, NASA reported that when it grew spirulina under ideal conditions, it could create products that were 70% protein. 

According to the U.S. Department of Agriculture (USDA), 100 grams of fresh spirulina contains: 

  • 90.7 grams of water
  • 5.92 grams of protein
  • 0.39 grams of fat
  • 2.42 grams of carbohydrates
  • 0.4 grams of fiber
  • 0.3 grams of sugar
  • 12 milligrams of calcium
  • 2.79 milligrams of iron
  • 19 milligrams of magnesium
  • 11 milligrams of phosphorus
  • 127 milligrams of potassium
  • 98 milligrams of sodium

It also contains a large number of vitamins and minerals, including: 

Dried samples will contain all of these nutrients in approximately the same ratios, just with a lot less water. 

Spirulina also contains 18 different amino acids, which are the building blocks of proteins. But, like most plant proteins, spirulina is not considered a complete protein. Complete proteins have all of the essential amino acids that our bodies aren’t able to produce. 

A diet that mostly derives protein from spirulina needs to be supplemented with sources that contain amino acids like lysine and histidine. You also need to eat a lot of spirulina to get a lot of protein from it. You can eat reasonable quantities of nuts or legumes to get just as much protein as from very large helpings of spirulina.  

Is spirulina safe to consume? 

The U.S. Food and Drug Administration (FDA) has classified spirulina as a food product that’s generally recognized as safe (GRAS). Spirulina extracts are approved as a safe coloring additive in frostings, ice cream, beverages, and a large number of additional food products. It produces a blue-green color. 

If you’re a healthy person, then spirulina is a good source of protein and other nutrients and shouldn’t cause any negative side effects. But there are certain groups of people who should be cautious about incorporating it into their diets. Always talk to your doctor before adding any new supplements to your routine.

You should only buy spirulina from a trusted source. Like other algae, naturally occurring spirulina can be contaminated with harmful microorganisms and radioactive metals, including: 

Who shouldn’t take spirulina? 

Given that so little is known about spirulina, there are certain categories of people who should avoid consuming any. These include: 

  • Children: There isn’t enough research on the safety of this product in children to recommend it for anyone under 18 years old. 
  • People who are pregnant or breastfeedingThere’s no point risking any contamination that could be present in the algae. Certain contaminants can be particularly harmful to infants. 
  • Anyone with phenylketonuria: This is a rare condition where people cannot process a particular amino acid — phenylalanine. Spirulina contains this amino acid, so you’ll need to avoid it. 
  • Anyone with an autoimmune disease: This includes conditions like multiple sclerosis, Crohn's disease, and rheumatoid arthritis. Spirulina seems to impact our immune systems in ways that we don’t yet fully understand. This means that it could potentially create complications in people with autoimmune conditions. 
  • People taking immune-suppressing medications: This includes medications like adalimumab and cyclosporine. Since the effect of spirulina on our immune systems isn’t fully understood, it could interfere with the effects of these medications. 
  • People taking the blood thinner warfarin: There’s a chance that spirulina could interfere with this drug too.


Vitamin D Deficiency: How Much Vitamin D Is Enough? See Slideshow

What are the benefits of taking spirulina? 

Besides being a healthy source of nutrients, there could be a number of health benefits to taking spirulina. Many studies show early support for the positive health effects of this food and supplement. This includes supposed anti-inflammatory and other immune-boosting properties.  

The problem is that all of the evidence in humans is very preliminary. The studies have low numbers of participants, take place for short periods of time, and involve people with unique diets and conditions. But this shouldn’t be too discouraging. Research is ongoing. 

Some of the initial benefits highlighted in human studies include: 

  • Anti-inflammatory properties: Spirulina seems to be able to limit the production of histamine by mast cells, a type of white blood cell that’s part of your immune system. This can impact how your immune system functions and lead to decreases in inflammation. This can have widespread effects throughout your body and could potentially benefit a large number of diseases. Much more research is needed to understand this broad effect. 
  • Improved control of blood glucose levels: A handful of studies have investigated spirulina in people with type 2 diabetes. There does seem to be some initial evidence that it can help control blood glucose levels. We need more data before anything is certain, though. 
  • Positive effects on certain pre-cancerous conditions: One study found that taking spirulina caused a reduction in a precancerous condition called oral submucous fibrosis, which is common in Asian countries. More data is needed to fully understand spirulina’s connection to cancer
  • Improvements to allergic rhinitisOne small study showed a reduction in the symptoms of this condition after taking spirulina. This is an encouraging result but needs to be replicated and reproduced on a larger scale. 
  • A lowered risk of certain eye conditionsSpirulina contains zeaxantuin, which has independently been shown to reduce the risk of cataracts and age-related macular degeneration. But the effect of consuming spirulina on these eye conditions hasn’t been studied. 
  • Decreased times to exhaustion: A very small study showed that students taking spirulina for three weeks took longer to become exhausted when exercising at maximal levels.

Health Solutions From Our Sponsors

Medically Reviewed on 7/29/2022

European Archives of Oto-Rhino-Laryngology: "The effects of spirulina on allergic rhinitis."

European Journal of Applied Physiology: "Preventive effects of Spirulina platensis on skeletal muscle damage under exercise-induced oxidative stress."

Evidence-Based Complementary and Alternative Medicine: "Spirulina in Clinical Practice: Evidence-Based Human Applications."

Journal of Clinical and Diagnostic Research: "Spirulina and Pentoxyfilline – A Novel Approach for Treatment of Oral Submucous Fibrosis."

Journal of Medicinal Food: "Role of Spirulina in the Control of Glycemia and Lipidemia in Type 2 Diabetes Mellitus."

Mount Sinai: "Spirulina."

NASA Technical Reports Server: "Characterization of Spirulina biomass for CELSS diet potential."

University of Rochester Medical Center: "Spirulina."

U.S. Department of Agriculture: "Seaweed, spirulina, dried," "Seaweed, spirulina, raw."

U.S. Food and Drug Administration: "CFR - Code of Federal Regulations Title 21."