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9 biggest health benefits of spirulina

Written by John Davis

Last updated: December 29, 2022

Spirulina is a potent phytonutrient made by blue-green algae that’s a common ingredient in superfood products, but it’s an excellent supplement in its own right as well.

Spirulina can be used to boost antioxidant levels, decrease risk factors for heart disease, and even improve exercise performance. Check out these key benefits of this unique nutrient:

Spirulina benefits

1. Spirulina has a dense concentration of micronutrients

Produced by blue-green algae, spirulina may seem an unlikely superfood since it’s technically a type of bacteria, but in the same manner as plants, it uses the process of photosynthesis to manufacture energy.

Aztecs knew the power of spirulina, and it has recently become the focus of attention as a potential source of nutrition for astronauts since it can be grown in space. (1)

One tablespoon of dried spirulina delivers 4 grams of protein with only 20 calories; it also provides respectable amounts of many vital nutrients. (2)

Here’s what you can expect from supplementing 7 grams of spirulina daily: 21% RDA for copper, 15% RDA for vitamin B2, 11% RDA for both iron and vitamin B1, 4% RDA for vitamin B3.

2. Spirulina can reduce risk factors for heart disease

Several blood markers associated with heart disease can improve with supplementation of spirulina.

Both LDL cholesterol (the bad kind) and blood triglyceride counts drop when spirulina is added to the diet, and HDL cholesterol levels go up, effectively reducing the chances of developing heart disease.

A study of test participants with high cholesterol who took a gram of spirulina daily found LDL cholesterol levels fell by just over 10%, while blood triglycerides decreased by more than 16%. (3)

Trials using higher doses of 4.5 to 8 grams daily showed similar results. (4, 5)

 3. Spirulina decreases lipid peroxidation

Lipid peroxidation, which is an indication of oxidative damage to the body’s fatty structures, can raise the risk of developing serious diseases.

A small study with 37 patients suffering from type 2 diabetes noted lower levels of oxidative damage as well as higher levels of antioxidants in the blood from the addition of 8 grams of spirulina daily. (6,7, 8, 9).

4. Spirulina might help decrease blood pressure

Another risk factor for heart disease is hypertension (high blood pressure); and spirulina may be useful in decreasing blood pressure through bumping up production of nitric oxide.

This molecule acts in the signaling process that allows blood vessels to dilate and relax. (10)

While lower dosages aren’t effective, 4.5 grams of spirulina daily lowered readings in people who had normal blood pressure (11).

5. Spirulina can reduce free radicals in the body

Besides dropping the risk of developing heart disease, the use of spirulina may also help prevent other serious health issues related to oxidative damage (12).

The generous amounts of antioxidants found in spirulina can reduce the damage done by free radicals in the body; inflammatory responses are also positively impacted, which has beneficial effects on risk factors for chronic diseases (13).

6. Spirulina can improve allergy symptoms

Spirulina has been tested for its effectiveness in several other areas, including the treatment of allergic rhinitis, or the inflammation of nasal passages.

This condition can be triggered by environmental conditions such as exposure to animal hair, pollens, or substances that can differ between individuals.

One study with more than a hundred subjects suffering from allergic rhinitis found taking 2 grams of spirulina daily eased symptoms, including nasal congestion and discharge, as well as itching and sneezing. (14)

7. Spirulina could improve anemia

The lower level of red blood cells in the body characteristic of anemia can lead to general fatigue and overall weakness (15).

When anemic patients supplemented with spirulina, red blood cell counts rose; their immune systems also grew stronger (16).

8. Spirulina can improve endurance performance

Two separate studies indicated endurance was improved in subjects who included spirulina supplements, extending the time athletes were able to exert themselves before becoming fatigued (17, 18).

9. Spirulina could improve blood sugar regulation

Animal studies indicate spirulina may also have the potential to regulate blood sugar (19, 20).

In one small human trial following 25 patients diagnosed with type 2 diabetes, results appeared promising; on a two-gram daily dose of spirulina, subjects experienced substantial drops in blood sugar (21).

Spirulina side effects

Spirulina is safe for most people. The safety of spirulina as a dietary supplement was reviewed in 2011 by United States Pharmacopeia, an organization which certifies the safety and purity of supplements and medications (22).

The report reviewed the safety record of spirulina, as well as the current state of any regulatory actions against spirulina supplement manufacturers.

While the report noted a few case reports that had associated spirulina with side effects like liver dysfunction and allergic reaction, it also noted that these cases typically involved supplements with many different ingredients, only one of which was spirulina.

Other animal research suggested that even tremendously high amounts of spirulina, consumed over a long period of time, are not harmful.

Issues with spirulina are usually because of poor quality ingredients. The United States Pharmacopeia report did note that a few unscrupulous manufacturers had been advertising levels of purity, and independent lab certifications of purity, that they did not actually have.

This resulted in legal action against these manufacturers, and changes in the marketing practices of these companies. As long as you stick with a top-rated spirulina brand, you shouldn’t have any problems with purity.

Spirulina dosage

Most studies use doses of one to ten grams of raw spirulina per day. There’s still a lack of large, high-quality studies on spirulina in humans, so the dosages that have been used successfully range from about one to ten grams of raw spirulina powder per day.

Start your dosage on the low side and increase as needed. As with other more experimental supplements with poorly characterized optimal dosages, it’s best to start with a lower dosage (maybe one or two grams), then stepping up the dosage gradually if you are not getting the results that you want.

Spirulina benefits FAQ

Q: Can spirulina be harmful?

A: There is very little evidence that spirulina can be harmful. Studies in animals have found that it is exceptionally safe, even at very high doses.

A handful of case reports have described liver problems or allergic reactions in people taking supplements that include spirulina, but these almost inevitably involve supplements with many other herbal ingredients in addition to spirulina, making it very difficult to ascribe the cause to spirulina, especially considering the fact that animal research suggests that spirulina might actually protect your liver.

While the recommended dose is between one and ten grams, people often take up to 40 grams per day without any apparent issues. The strong safety profile of spirulina is one of its best selling points.

Q: Can you freeze spirulina?

A: If you buy spirulina but don’t want to use it right away, you can even freeze it. Just make sure you don’t unfreeze and refreeze your spirulina supplement over and over, because moisture will quickly make its way into your spirulina supplement and degrade its quality.

Powder form spirulina will also degrade more quickly after being opened, since it has a much greater surface area that is exposed to the air.

Q: What is spirulina?

A: Spirulina is produced by cyanobacteria, which are a type of “blue green algae” which produce energy via photosynthesis. Technically, spirulina isn’t produced by algae; it’s more in line with a probiotic than anything else.

Still, because the cyanobacteria produce their energy using sunlight, they have many of the same nutrients (including chlorophyll) that you’d get in a green leafy vegetable like chard or kale, but in a much more densely concentrated form.

You won’t get 100% of the benefits of raw veggies, because the spirulina produced by cyanobacteria lacks much in the way of fiber (though this is also allows spirulina to have such densely concentrated nutrients).

Q: Why is spirulina good for you?

A: Spirulina includes a dense mixture of antioxidants and micronutrients, making it a good way to augment your daily intake of phytonutrients.

Spirulina reduces a number of risk factors for heart disease, including blood cholesterol levels and blood pressure, so it’s great for your long-term well-being.

On top of that, spirulina appears to help alleviate allergies and could even improve endurance exercise performance, so it’s a very well-rounded supplement with a wide range of benefits.

Q: How can you make spirulina taste good?

A: The astringent and slightly sour taste of spirulina isn’t for everyone. It can taste just how it looks: green.

To get around this, you can mix it in with a great-tasting protein powder, or include it in a smoothie with natural non-caloric sweeteners like stevia that can mask some of the harsher notes and flavors in spirulina.

If you really can’t stand the taste of spirulina powder, you can always opt for a capsule-based supplement instead. That way, you won’t taste the powder at all.

Related: Our best spirulina picks


Spirulina is a naturally-occuring nutrient that shows great promise as an antioxidant and anti-inflammatory across a wide range of studies.

Though research in humans is still in the early stages, some research articles suggest that doses in the range of one to ten grams per day of raw spirulina are most effective.

It’s a great supplement on its own, and is also an excellent option to incorporate into protein shakes, green drinks, and smoothies.


John Davis

John Davis is a Minneapolis-based health and fitness writer with over 7 years of experience researching the science of high performance athletics, long-term health, nutrition, and wellness. As a trained scientist, he digs deep into the medical, nutritional, and epidemiological literature to uncover the keys to healthy living through better nutrition.