Spirulina is a type of blue-green algae that some people take as a dietary supplement. Potential benefits include positive effects on eye health, blood pressure, and cholesterol levels.

Spirulina is an algae that contains protein and vitamins, making it a suitable dietary supplement for people on vegetarian or vegan diets.

Research suggests it has antioxidant and inflammation-fighting properties and may help regulate the immune system.

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According to the United States Department of Agriculture (USDA), one tablespoon or 7 grams (g) of dried spirulina containsTrusted Source:

It also contains thiamin, riboflavin, niacin, folate, and vitamins A, B6, and K.

Spirulina contains a range of antioxidants, including phycocyanin, a blue-green pigment. Antioxidants, such as those in spirulina, may help fight free radicals and protect the body from cell damage.

Free radicals form in the body due to natural processes and exposure to harmful substances, such as alcohol, tobacco, and some foods. They can cause tissue damage and may increaseTrusted Source the risk of certain health conditions, such as cancer.

Spirulina contains the antioxidant beta carotene. The body converts beta carotene into vitamin A, which plays a key roleTrusted Source in eye health.

In a 2019 animal study, researchers gave mice either a standard diet or a diet containing 20% spirulina for 4 weeks. Then, they left the mice in darkness, followed by 1 hour of white light exposure.

The mice that consumed spirulina had better protection and less damage to the retina and photoreceptors in their eyes. However, more research is necessary to see if these results apply to humans.

It is worth noting that nutrients vary between products, and products in experiments may be different than those available to consumers. For example, the spirulina product that the USDATrusted Source analyzes contains no zeaxanthin and only small amounts of beta carotene.

A 2022 study involving 60 people with periodontitis tested spirulina’s antioxidant effects on gum disease. Half of the participants had Scaling and Root planning (SRP) treatment and a placebo, and the other half had SRP treatment with spirulina.

The researchers suggested that local drug delivery of spirulina with SRP treatment may have a beneficial antioxidant effect on chronic periodontitis.

A 2022 review looked at spirulina’s effects on managing oral submucous fibrosis, a chronic precancerous condition that affects the throat and mouth.

The studies in the review suggested spirulina may be effective at managing this condition. However, the researchers highlight that current evidence has a high risk of bias, and more research is necessary.

Various algae types may benefitTrusted Source oral health due to their antimicrobial activity. This may make them a useful therapy for caries and other bacterial and fungal infections. However, more research is necessary to support this.

A 2020 review suggests that spirulina may have benefits for reducing:

It may also help to improve the levels of fats in the blood. One possible reason is that ingredients in spirulina prevent the small intestine from absorbing as much fat.

However, further research, including larger clinical trials, is necessary to confirm these potential effects.

Some animal research suggests that spirulina may affect gut health.

For example, a 2017 studyTrusted Source on older mice suggests that spirulina may preserve healthy gut bacteria during the aging process. However, more research is necessary to understand how spirulina may affect gut health in humans.

Research in a 2018 review suggests that spirulina can significantly lower fasting blood sugar, as well as other cardiovascular and metabolic biomarkers.

A 2021 meta-analysis of eight studies also found that spirulina significantly reduced the following markers in people with type 2 diabetes:

  • fasting blood sugar
  • triglycerides
  • total cholesterol
  • low density lipoprotein cholesterol
  • very low density lipoprotein cholesterol

It also increased high density lipoprotein, which some people may call “good” cholesterol in the population.

A 2023 review suggests that spirulina supplementation may help to:

However, more research, including larger trials with a varied candidate pool, is necessary.

A 2021 review suggests that spirulina may help to prevent and treat high blood pressure.

Research in the review suggests that spirulina supplementation significantly reduced systolic and diastolic blood pressure. The reductions were greater in people with high blood pressure than typical blood pressure levels.

However, reduction also varied in different control trials. The researchers suggest that other factors may affect the results, including:

  • general diet
  • physical activity levels
  • smoking status

More research is necessary to understand the full effects of spirulina on blood pressure levels.

High blood pressure and high cholesterol levels can both increaseTrusted Source a person’s risk of heart disease.

Research in a 2024 article suggests that spirulina may have potential benefits for various heart-related diseases. It may work by limiting or preventing risk factors for these conditions, including:

  • high blood pressure
  • high blood sugars
  • high levels of fats in the blood

However, more research is necessary, particularly to learn if dosage and timing may affect spirulina’s therapeutic potential.

People may experience allergic rhinitis in response to allergens, such as dust mites, pet hair, or pollen.

In 2020, researchersTrusted Source gave 53 people with allergic rhinitis either 2 g per day of spirulina platensis or 10 g per day of cetirizine (Zyrtec).

Results suggested that spirulina could be an alternative therapy for the symptoms of allergic rhinitis, but larger studies are necessary.

A 2023 test tube study suggests that spirulina may have protective effects against metal pollutants, such as:

The authors suggested that current research shows promising results, but more studies are necessary to understand the extent of spirulina’s protective benefits.

A 2022 review discusses the potential neuroprotective effects of spirulina. It summarizes that spirulina may have a positive effect on the activation of glial cells, which support and protect nerve cells.

Spirulina may also have benefits in the treatment of neurodegenerative conditions, such as:

  • Alzheimer’s disease
  • Parkinson’s disease
  • multiple sclerosis

However, more research in humans is necessary.

The dosage of spirulina products in research varies from study to study. However, a 2022 review suggests a safe dose for adults is between 3 and 10 gTrusted Source daily.

People should not exceed the dose on the product label. They can speak with a healthcare professional if they have any concerns about the ideal spirulina dosage.

The 2022 review suggests that 30 g dailyTrusted Source is the maximum limit for spirulina. A 2018 review suggests that people typically tolerate spirulina well.

However, the Food and Drug Administration (FDA) does not regulate spirulina, and some studiesTrusted Source have found high levels of contaminants in spirulina products.

Exposure to these contaminants may lead to liver damage, gastrointestinal symptoms, and skin rashes, among other severe complications.

The following people should discuss spirulina supplements with a doctor before taking them:

  • pregnant people
  • older adults and children
  • people with weak immune systems
  • people taking other medications or supplements

People should also obtain spirulina and other supplements from a reputable source.

There have also been some cases of allergic reactions to spirulina. An allergic reaction can sometimes lead to anaphylaxis, a life threatening health condition that can result in anaphylactic shock.

Anyone who experiences swelling, hives, or difficulty breathing after consuming spirulina should seek immediate medical attention.

Spirulina is available in powder or tablet form.

As a powder, people can:

  • add it to smoothies or juices
  • sprinkle it on salads or in soups
  • mix it into energy balls

People can also take spirulina as a dietary supplement in tablet form.

What does spirulina do to the body?

ResearchTrusted Source suggests spirulina has anti-inflammatory, antioxidant, antimicrobial, and cholesterol-lowering properties. It may have benefits for conditions ranging from gum disease to diabetes, but more research is necessary to confirm many of these uses.

How does spirulina affect weight?

A 2019 meta-analysisTrusted Source found that spirulina reduced body weight, body fat percentage, and waist circumference, particularly in people with obesity, which could make it useful as part of a weight management program. However, more research is necessary.

Is spirulina safe?

A 2022 review suggests that a safe dosage of spirulina is between 3 and 10 gTrusted Source daily for most adults.

People should always buy from a reputable source and follow the instructions on the label. Some studiesTrusted Source also highlight contamination in spirulina products, which could have adverse health effects.

Further resources

For more in-depth resources about vitamins, minerals, and supplements, visit our dedicated hub.

Spirulina contains a range of nutrients and antioxidants that may make it a suitable remedy for various diseases.

However, more research is necessary before healthcare professionals are likely to recommend spirulina as a treatment for various health conditions.

Anyone interested in using spirulina as a supplement should first speak with a doctor. They should also ensure they only purchase products from a reputable source, as there is a risk of contamination.