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9 Health Benefits of Spirulina (Tablets, Capsules, Powder)

Written by Carlos Tello, PhD (Molecular Biology) | Last updated:
Jonathan Ritter
Puya Yazdi
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology), Puya Yazdi, MD | Written by Carlos Tello, PhD (Molecular Biology) | Last updated:

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Once declared the “best food for the future” by the World Health Organization, this blue-green algae is a protein-rich antioxidant that may support and maintain your immune system. Read on to learn more about spirulina.

What Is Spirulina?

Spirulina is a dried supplement made from two species of blue-green algae, Arthrospira platensis and Arthrospira maxima. The Kanembu tribe in Chad call it dihé; the Aztecs who lived in the valley of Mexico called it tecuitlatl [1, 2, 3, 4].

The algae naturally grows in warm freshwater lakes like Lake Texcoco in Mexico and Lake Chad, which sits on the border of Chad, Niger, Nigeria, and Cameroon. Locals traditionally harvest the algae and dry it in “cakes” [4].

Once it’s been dried, spirulina contains up to 70% protein, is a nutrient-rich antioxidant, and takes less land, water, and energy to produce than staple crops like corn and soy. Farmers use it to enrich their animal feeds and improve the quality of meat they produce. It pulls huge quantities of carbon dioxide out of the atmosphere, and it may even be used to convert city sewage back to clean water [1, 5].

Spirulina gathered attention as a possible pharmaceutical in the 1940s and 50s. In 1974, the World Health Organization declared it the “best food for the future” to combat malnutrition, especially in children [4].

To learn more about spirulina’s nutritional value and how it might work, check out this post.

Spirulina is a dried blue-green algae that contains 70% protein once dried. It is considered an important “food for the future” by the WHO.

Snapshot of Spirulina

Proponents

  • Powerful antioxidant
  • High in protein and full of nutrients
  • May reduce the risk of heart disease
  • May reduce inflammation, especially in allergies, and boost immunity
  • May lower blood sugar
  • May possibly prevent fatigue
  • May protect the liver, brain, and kidneys

Skeptics

  • Some potential benefits have been insufficiently investigated
  • May cause rare allergic reactions
  • Occasional contamination with other cyanobacteria
  • May interact with some medication

Health Benefits of Spirulina

Spirulina supplements have not been approved by the FDA for medical use and generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing.

Effective For

1) Antioxidant Activity

When free radicals build up, they disrupt structures, machinery, and even DNA inside cells. This process is linked to a great many diseases, including cancer, Alzheimer’s disease, Parkinson’s disease, and arthritis [6, 7].

The most robust benefit of spirulina is probably its antioxidant effect. Multiple cell, animal, and human studies have demonstrated its ability to reduce oxidative stress; furthermore, spirulina contains diverse active compounds with antioxidant activity. It may contribute to whole-body health and, when combined with diet and lifestyle choices, delay or prevent disease onset [8, 9, 1].

Likely Effective For

2) Heart Health

A review of 12 human clinical studies suggested that spirulina may protect the heart not only through its antioxidant properties, but also by lowering cholesterol, triglycerides, and blood pressure [9].

Blood Pressure

Multiple clinical studies revealed that spirulina lowers blood pressure. In particular, the diastolic blood pressure – the lower of the two numbers, measured when the heart is resting between beats – is significantly decreased in people taking spirulina supplements [10, 11, 9].

Cholesterol and Triglycerides

High levels of cholesterol and triglycerides increase a person’s risk of heart disease and stroke [12, 13, 14].

In animal and human studies, spirulina decreased total cholesterol, LDL (the “bad” cholesterol), and triglycerides in the blood. These markers may increase as we age; spirulina may, therefore, have key benefits in elderly people or in those prone to high levels [15, 9].

The existing evidence suggests that spirulina reduces the risk of heart disease. Although spirulina supplements are not FDA-approved for this purpose, you may discuss with your doctor if they may be helpful in your case.

Possibly Effective For

3) Inflammation

Inflammation, like oxidative stress, is linked to many different conditions. Inflammatory diseases include everything from depression to IBD to arthritis [16, 17, 18].

Spirulina contains multiple bioactive compounds that are known to reduce inflammation. Taken as a supplement, spirulina blocks the activity of molecules that stimulate the inflammatory response. In both human and rat studies, it reversed an age-related increase in inflammatory cytokines [1, 8, 15].

In Allergic Rhinitis

Allergic rhinitis is the most common allergic reaction to environmental allergens like pollen; it is also a major part of asthma. In one clinical study on 150 people, spirulina decreased all measured symptoms of allergic rhinitis compared to placebo [19, 20].

Although limited, the evidence suggests that spirulina may help with allergic rhinitis and other inflammatory conditions. You may try spirulina if your doctor determines that it may help. Never take it instead of what your doctor recommends or prescribes.

4) Boosting Immunity

Animal and human studies have demonstrated spirulina’s immune-boosting properties. By activating white blood cells and the tissues that produce them, it may help the body defend against bacteria, viruses, and even tumors without causing excessive inflammation [21].

In a clinical trial on 169 HIV-infected people, daily supplementation with spirulina (along with a balanced diet) increased the levels of immune cells (CD4) and reduced the viral load after 6 months [22].

Similarly, spirulina reduced viral load and liver damage in a trial on 30 people with hepatitis C [23].

Spirulina extract improved natural killer cell activity in 2 small trials on14 healthy people [24, 25].

In a trial on 19 rowers, supplementation with spirulina protected against the deficit in immune function caused by strenuous exercise (increased Treg over natural killer cell proportion) [26].

Again, limited evidence suggests the potential of spirulina to boost immunity in both healthy and sick individuals. You may discuss with your doctor how it may help in your case.

5) Lowering Blood Sugar

We need sugar to keep a supply of energy available for our bodies, but high blood sugar can lead to insulin resistance and diabetes. In a review of 12 clinical studies, spirulina significantly reduced fasting blood glucose. Clinical studies suggest it may also increase sensitivity to insulin [9, 8].

However, some researchers dispute the claim that spirulina can lower blood sugar in type 2 diabetes: twelve weeks of spirulina tablets (8 g/day) didn’t change blood sugar levels in a group of 37 diabetic Koreans. Each person’s health status (and possibly race) may affect their response to spirulina [9, 27].

According to the evidence, spirulina seems to help lower blood sugar. The results are, however, mixed, suggesting individual factors may play a key role in its effectiveness. Further clinical research is needed to shed some light on these discrepancies.

Insufficient Evidence for:

6) Fatigue

Spirulina may improve exercise output and prevent fatigue. In a study of 18 adult men, both short- and long-term spirulina supplementation slightly, but significantly improved exercise output and reduced both physical and mental fatigue [28].

In a second, limited study of only nine “moderately trained” adult men, it improved markers of physical endurance. The evidence for this effect is limited, but promising [29].

However, spirulina was ineffective at improving chronic fatigue in a series of 4 trials on 4 physicians [30].

Three small clinical trials with mixed results cannot be considered sufficient evidence that spirulina improves fatigue. Larger, more robust clinical studies are needed.

7) Chronic Arsenic Poisoning

Arsenic is an element found naturally in very low levels in the environment and in much higher concentrations in (now banned) pesticides and wood preservatives. In some parts of the world, people are exposed to low levels of arsenic in their drinking water and suffer chronic poisoning as a result [31, 32].

In a human trial on 41 people, spirulina and zinc supplements improved symptoms of arsenic poisoning. People taking the supplements cleared more arsenic in their urine and had less arsenic in their tissues [32].

In one study, the hexane extract of spirulina cleared almost 90% of arsenic built up in rat liver tissues. A second tissue study suggested it was more effective than the typical (alcohol) extract at removing arsenic. However, this extract is NOT commercially available, as hexane is otherwise toxic to the brain [33, 34, 35].

Only one clinical trial and some animal studies have been conducted, making the evidence insufficient to support the use of spirulina for chronic arsenic poisoning. Further clinical research is required.

8) Liver Support

In a limited human study of three people, 4.5 g/day of spirulina lowered blood cholesterol and triglyceride levels and improved symptoms of fatty liver disease, indicating it might be helpful in people with this disease [36].

Unsurprisingly, one of the reasons why spirulina may support liver function is tied to its antioxidant property. In diabetic rats, spirulina protected liver tissues against oxidative stress and improves markers of liver function [37].

Spirulina may also protect the liver from damage caused by a high-fat diet, as demonstrated in rats. It may also protect the liver from age-related inflammation by optimizing the gut microbiome [38, 39].

A small clinical trial and some animal research are clearly insufficient to conclude for certain that spirulina supports liver function. More clinical trials are needed to validate these preliminary results.

Animal and Cell Research (Lack of Evidence)

No clinical evidence supports the use of spirulina for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies should not be interpreted as supportive of any health benefit.

9) Protecting the Brain

Too much iron in the brain increases oxidative stress, damages neurons, and may trigger a cognitive decline. Spirulina’s antioxidant effects may reverse this stress. Likewise, spirulina decreased harmful inflammation in microglial cells, which is thought to underlie diseases like Alzheimer’s [1, 40, 41].

In one cell-based study, an extract of spirulina prevented neuron death by increasing a signaling pathway involving BDNF and CREB – both of which protect neurons from damage and maintain brain function and flexibility during stress [42, 43].

In rats with Parkinson’s disease, spirulina decreased cell death of neurons that produce and release dopamine. Researchers have yet to investigate spirulina’s effect in people with Parkinson’s disease; however, there is significant interest in studying phycocyanobilin in Parkinson’s and Alzheimer’s disease [44, 45].

10) Kidney Support

Many commonly-used drugs are excreted by the kidneys. This work taxes the kidneys and exposes them to damage. Similarly, in people with diabetes, the kidneys struggle under an increased oxidative load. Spirulina’s antioxidant properties prevent oxidative stress in the kidney; in animals, spirulina supports the kidneys while they process medication and filter toxins out of the blood [46, 47, 48, 49].

Cancer Research

Oral leukoplakia is a white patch on the mouth lining that cannot be rubbed off. The condition is more frequent among tobacco smokers or chewers and is associated with an increased incidence of mouth cancer. Spirulina resolved oral leukoplakia in 45% of cases in a clinical trial on 87 tobacco chewers, suggesting its potential to prevent mouth cancer [50].

Spirulina activates natural killer cells, which may improve the body’s immune response to tumors [21].

It may also block tumor development more directly. In one study, rats were dosed with a carcinogenic toxin and either supplemented with spirulina or not. 20% of the rats given spirulina developed tumors, compared to 80% of the control group. In multiple cell and animal studies, spirulina slowed or reversed tumor growth [51, 52, 53].

Furthermore, in a cell study, spirulina was a stronger antioxidant and had more anti-cancer activity than a similar blue-green algae called chlorella [54].

Note, however, that spirulina supplementation may increase death rates when combined with the chemo drug fluorouracil, according to one mouse study. The mechanism of spirulina’s anti-cancer effect is still under investigation; it may be subject to drug interactions or only be protective under certain conditions [55].

Taken together, the evidence is very limited and clearly insufficient to support the use of spirulina in cancer prevention or therapy. Importantly, never use spirulina (or any other supplements) in place of proven anticancer therapies.

Limitations and Caveats

While nutrition is generally reported based on 100 g of dried material, most people will never consume that much at a time, and clinical research reflects this. Most clinical studies investigated doses between 2 g and 10 g daily.

While the people who traditionally live near Lakes Texcoco and Chad may attest to the safety of much larger quantities of spirulina, modern research has yet to investigate this in human trials.

Many of the health benefits of spirulina have only been tested in cell or animal studies. Given how promising these early studies have been, many more human clinical trials are probably on the horizon which will undoubtedly change our understanding of its mechanisms.

Supplementation & Dosage

Spirulina is available in powder, pill, capsule, and liquid extract. Traditionally, it has also been eaten as a dried “cake.” All spirulina supplements are made from the biomass of the whole organism: spirulina is a cyanobacterium, not a plant [4].

Note that some supplements marketed as “blue-green algae” may be spirulina, but they may also be chlorella or klamath. If you are looking specifically for spirulina supplements, make sure to buy a high-quality supplement that only lists spirulina on the label [56].

Spirulina pills and capsules can be swallowed like any other pill or capsule. The powder and liquid extract can be mixed into drinks, smoothies, yogurt, or other foods.

Dosage

Because spirulina is not approved by the FDA for any conditions, there is no official dose. Users and supplement manufacturers have established unofficial doses based on trial and error. Discuss with your doctor if spirulina may be useful as a complementary strategy in your case and which dose you should take.

Clinical studies have used a range of doses to investigate spirulina’s effects. People have seen beneficial effects from as little as 400 mg per day, though most studies used doses of between 2 g and 10 g per day [1].

Toxicological studies show that spirulina is very well tolerated; rats fed spirulina as nearly half of their complete diet had no chronic negative effects. You may wish to start at a lower dose and increase it slowly [57].

Pet Food Supplement

As more and more people move away from commercial kibble diets for their pets, pet owners are looking for nutritious supplements and additives to keep their dogs and cats in top condition. Spirulina is a popular supplement for pets on a homemade raw diet [58, 59, 60].

Only one study has investigated the effect of spirulina on dogs; this study found that spirulina polysaccharides protected the bone marrow from damage caused by chemo- and radiotherapies. In one cat study, spirulina increased the activity of immune cells. Because of its excellent safety profile and history of animal feeding, spirulina is considered safe to feed to dogs and cats [61, 62, 21, 63].

In dog diets, spirulina is used as a source of vitamins, iodine, and trace minerals. It should only be used as a supplement and not as a primary protein source [63].

User Experiences

The opinions expressed in this section are solely those of spirulina users, who may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfHacked. SelfHacked does not endorse any specific product, service, or treatment.

Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare providers because of something you have read on SelfHacked. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.

Most online user reviews for spirulina supplements are positive. People reported having more energy, lower cholesterol, increased physical performance, and fewer infections. Some people reported side effects, including nausea, indigestion, heartburn, and migraine. Of these, some admitted that these side effects may have been caused by other medication or foods, or by underlying physical conditions.

Takeaway

Spirulina is the dried product of two species of cyanobacteria, or blue-green algae. It has been a staple food for people living around Lakes Texcoco and Chad for centuries; the health effects of its active phycocyanins, phenols, and polysaccharides more recently made it a popular supplement. It also seems to be a safe supplement for pets and a good feed for livestock animals.

Spirulina has significant antioxidant, anti-inflammatory, and immune-boosting effects. It may lower blood pressure, blood sugar, cholesterol, and triglycerides and may prevent certain types of allergic reactions. It may also fight cancer and protect the brain, kidneys, and liver. Some studies suggest that it may be used to manage chronic arsenic poisoning.

Spirulina is available as a powder, capsule, pill, or tincture. As little as 400 mg per day may be effective, but most clinical studies used between 2 and 10 g per day.

Further Reading

About the Author

Carlos Tello

Carlos Tello

PhD (Molecular Biology)
Carlos received his PhD and MS from the Universidad de Sevilla.
Carlos spent 9 years in the laboratory investigating mineral transport in plants. He then started working as a freelancer, mainly in science writing, editing, and consulting. Carlos is passionate about learning the mechanisms behind biological processes and communicating science to both academic and non-academic audiences. He strongly believes that scientific literacy is crucial to maintain a healthy lifestyle and avoid falling for scams.

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