Spirulina is a type of blue-green algae that people can take as a dietary supplement. People consider spirulina a superfood due to its nutritional content and potential health benefits. How much spirulina a person takes per day can vary.

Spirulina 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 the ability to help regulate the immune system.

This article discusses 13 potential health benefits people may get from adding spirulina to their diet.

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Consuming spirulina is one way to supplement protein and vitamins in the diet.

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

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.

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 contribute to inflammation and possibly some cancers.

Antioxidants, such as those in spirulina, may help fight free radicals and protect the body from cell damage.

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

In research published in 2019, scientists gave mice either a standard diet or a diet containing 20% spirulina for 4 weeks. Then, they left the mice to spend time 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. This suggests spirulina might help protect eye health in humans, although more research is needed.

It is worth noting that nutrients vary between products, and products used in experiments may not be the same as those available to consumers. The spirulina product analyzed by the USDA contains no zeaxanthin and only small amounts of beta carotene.

Find out more about preventing common eye problems.

Spirulina has shown promise for treating and preventing gum disease and other oral health problems.

In 2013, scientists treated 64 sites of gum disease with scaling and root planing and applied a spirulina gel to 33 of the sites. After 120 days, pocket depth in all sites had improved, but those treated with spirulina were significantly better.

Leukoplakia is a condition where lesions form in the mouth, usually due to tobacco use. Sometimes, it can become cancerous. In a small, older study, 44 people with leukoplakia took 1 g of spirulina per day. After 12 months, the lesions had disappeared in 20 participants. After stopping the supplements for a year, nine participants found their lesions returned.

Various algae types may benefit oral health due to their antimicrobial activity. This could make them useful for treating or preventing caries and other bacterial and fungal infections.

What can people do to improve dental and gum health?

A 2020 review concludes that including spirulina in the diet could help reduce:

  • body mass index (BMI)
  • body fat
  • waist circumference
  • appetite
  • blood lipids

One possible reason is that ingredients in spirulina prevent the small intestine from absorbing as much fat.

However, further research, including larger clinical trials, would be warranted to confirm these benefits.

Find out more about weight management here.

Animal studies indicate spirulina may support gut health as people age. A 2017 study on older mice suggests that spirulina may preserve healthy gut bacteria during the aging process.

Spirulina does not contain much fiber, so people should eat it alongside other gut-healthful, high fiber foods.

More research is needed to confirm whether spirulina can benefit the gut health of humans.

Learn about 10 ways to improve gut health.

Spirulina may help manage blood sugar levels, which is important for people with diabetes, although more research is needed.

A 2018 review found that taking spirulina significantly lowered fasting blood glucose levels.

In a 2017 animal study, researchers gave mice with type 1 diabetes spirulina extract orally. Results in the mice indicated:

  • lower blood sugar
  • higher insulin levels
  • improved liver enzyme markers

The findings suggest that ingredients in spirulina could play a protective role in type 1 diabetes, but more research is needed.

Which herbs and supplements can help with type 2 diabetes?

Taking spirulina extract may help to lower cholesterol levels. High cholesterol levels can increase the risk of heart disease.

A 2016 review suggests that spirulina supplements may positively impact blood lipids, which are fats in the blood. The authors found evidence that spirulina can significantly reduce total cholesterol and low-density lipoprotein (LDL), “bad” cholesterol while increasing high-density lipoprotein (HDL), “good” cholesterol.

In a 2013 study, researchers found that taking 1 g of spirulina daily reduced people’s total cholesterol after 3 months.

Find out more about high cholesterol here.

As well as lowering cholesterol, spirulina may help manage blood pressure.

A small-scale 2016 study found that taking spirulina regularly for 3 months reduced the blood pressure of people with overweight and hypertension.

What are some ways to lower blood pressure naturally?

High blood pressure and cholesterol levels are both linked to heart disease.

A 2018 review suggests that spirulina could help prevent chronic inflammatory diseases, such as heart disease. This might be due to its impact on blood pressure, glucose levels, and lipid levels.

Learn about heart-healthy foods here.

Spirulina may help boost a person’s basal metabolism. A higher metabolic rate may increase the number of calories they burn, which may aid weight loss.

In a small-scale 2014 study, people who took 6 g of spirulina a day experienced beneficial metabolic effects, alongside weight loss and better health-related quality of life.

The participants all had nonalcoholic fatty liver disease, and more research is needed to see if spirulina may boost metabolism in others without this condition.

Find out some myths and facts about metabolism.

When a person has allergies to pollen, dust, or pets, the inside of their nose may swell. This reaction is called allergic rhinitis. There is some evidence that spirulina could help improve the symptoms of this condition.

A 2013 study states that spirulina can relieve nasal inflammation and reduce histamine in the body. Compared to a placebo, it may reduce the symptoms of allergic rhinitis, including:

  • runny nose
  • sneezing
  • nasal congestion
  • itching

In 2020, researchers gave 53 people with allergic rhinitis either 2 g per day of spirulina platensis and others 10 g per day of cetirizine (Zyrtec). Results indicated that spirulina could be a suitable alternative treatment, but larger studies are needed.

In some places, there is a risk of poisoning from contaminated drinking water and other sources of pollutants. In 2006, some researchers suggested that spirulina may offer a treatment option.

In 2016, a review found evidence of antitoxic properties in spirulina that could make it useful alongside other treatments for counteracting pollutants, such as:

The authors suggested that spirulina could support clinical treatment in cases of pollutant poisoning, but larger studies are needed to confirm this.

A 2018 paper suggests spirulina could play a role in treating mood disorders.

The theory is that spirulina is a source of tryptophan, an amino acid that supports serotonin production. Serotonin plays an important role in mental health.

Depression, anxiety, and other mental health conditions can involve low levels of serotonin. Taking tryptophan supplements to maintain serotonin levels could help support mental well-being.

However, more studies are needed.

People should speak with a doctor or another healthcare professional before using spirulina to boost their physical or mental well-being.

Spirulina is a blue-green algae product.

According to the National Institutes of Health (NIH), people have used doses of up to 19 g per day for a maximum of 2 months and up to 10 g per day for a maximum of 6 months.

People should not exceed the dose stated on the product label.

Research has not confirmed a safe upper limit for taking spirulina, but the NIH notes that taking too much can lead to:

  • nausea
  • vomiting
  • diarrhea
  • headache
  • dizziness

The Food and Drug Administration (FDA) does not regulate spirulina, and some studies have found high levels of contaminants in spirulina products.

These can lead to liver damage, vomiting, weakness, a rapid heartbeat, shock, and possibly death.

Spirulina may not be safe to use:

  • during pregnancy
  • for children
  • with autoimmune diseases such as multiple sclerosis and rheumatoid arthritis, as it can increase immune activity
  • before or after surgery, as it may affect blood glucose levels

Before taking spirulina, people should talk with a doctor to ensure it will not interact with other drugs and that it is safe for them to use.

They should also obtain spirulina and other supplements from a reputable source and ensure that the product has undergone safety testing.

The FDA has previously issued warnings about misleading claims for products sold online that contain spirulina.

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 needs immediate medical attention.

Further resources

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

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Spirulina is available in powder or tablet form.

As a powder, people can:

  • add it to smoothies, which gives the drink a green color
  • sprinkle spirulina powder on salads or in soups
  • mix it into energy balls with other healthy ingredients
  • stir a tablespoon into fruit or vegetable juices

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

Here are some questions people often ask about spirulina:

What does spirulina do to the body?

Evidence suggests spirulina has anti-inflammatory, antioxidant, antimicrobial, and cholesterol-lowering properties. It may help treat or manage conditions ranging from gum disease to depression, but more research is needed to confirm many of these uses.

How does spirulina affect weight?

Research suggests spirulina can help reduce body fat, waist circumference, BMI, and appetite, which could make it useful as part of a weight-management program.

Is spirulina safe?

A person should always buy from a reputable source, check it has undergone testing, and follow the instructions on the label. It may not be safe during pregnancy, for children, and for those with an autoimmune disease. Some studies have found contamination in spirulina products, which could be dangerous.

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

However, more research is needed before doctors can recommend spirulina to treat any health condition.

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