Spirulina

What is spirulina?

Spirulina is a blue-green algae that grows in both fresh and salt water. It is also produced commercially for use in dietary supplements (34, 35). Spirulina belongs to the cyanobacteria family, a family of unicellular microbes. Just like plants, cyanobacteria can produce energy from sunlight through the process of photosynthesis. Because spirulina contains 60% protein, as well as numerous vitamins and minerals, this algae is also consumed as food in parts of Mexico and Africa (34). Spirulina was already consumed by the ancient Aztecs and became popular again when NASA came up with the idea of growing spirulina in space for use by astronauts (1). Spirulina is also a good source of polyunsaturated fats and the antioxidants C-phycocyanin and beta-carotene (34, 36). Spirulina is also touted as a dietary supplement with antibacterial, antioxidant, anti-inflammatory, immune boosting and cholesterol-lowering properties (37). Spirulina is one of the most popular dietary supplements. Spirulina is overloaded with nutrients and antioxidants that can benefit the body and brain.

Spirulina is packed with nutrients

This tiny algae is packed with nutrients. One tablespoon (7 grams) of dried spirulina powder contains (2):

Protein: 4 grams
Vitamin B1 (thiamine): 11% of the daily requirement
Vitamin B2 (riboflavin): 15% of the daily requirement
Vitamin B3 (niacin): 4% of the daily requirement
Copper: 21% of the daily requirement
Iron: 11% of the daily requirement
Spirulina also contains useful amounts of magnesium, potassium, manganese and small amounts of almost every other nutrient the body needs.

In addition, this amount of spirulina provides only 20 kcal and 1.7 grams of digestible carbohydrates.

Gram for gram, spirulina may be by far the most nutritious food on the planet. One tablespoon (7 grams) of spirulina also provides a small amount of fat - about 1 gram - which contains both omega-6 and omega-3 fatty acids in a ratio of 1.5 to 1. The quality of the protein contained in spirulina is considered excellent, even when compared to egg protein. It provides all the essential amino acids needed by the human body. It is often claimed that spirulina also contains vitamin B12, but this is not true. Rather, spirulina contains pseudovitamin B12, which has no effect in humans (3, 4).

Potential health benefits of spirulina

Spirulina has a number of potential health benefits, the most important of which we will briefly review along with the scientific evidence.

Spirulina has strong antioxidant and anti-inflammatory properties

Oxidative damage can destroy the DNA of cells. This damage can promote chronic inflammation, which can contribute to cancer and other diseases (5). Spirulina is a fantastic source of antioxidants that can protect against oxidative damage. The main component is called phycocyanin. This substance also gives spirulina its blue-green color. Phycocyanin can fight free radicals and inhibit the production of pro-inflammatory signaling molecules, which can have impressive antioxidant and anti-inflammatory effects (6, 7, 8).

Summary: Phycocyanin is the primary active compound in spirulina. It has impressive antioxidant and anti-inflammatory properties.

Spirulina can lower "bad" LDL cholesterol and triglyceride levels Heart disease is the leading cause of death worldwide. Many risk factors are associated with an increased risk of heart disease. Spirulina has been shown to positively influence many of these factors. For example, it can lower total cholesterol levels, LDL "bad" cholesterol levels and triglyceride levels, while increasing levels of HDL "good" cholesterol. In a study of 25 subjects with type 2 diabetes, 2 grams of spirulina per day significantly improved these markers (9). Another study of subjects with high cholesterol levels found that 1 gram of spirulina per day could reduce triglyceride levels by 16.3% and LDL "bad" cholesterol levels by 10.1% (10). Several other studies have also found desirable effects - although higher doses in the range of 4.5 to 8 grams per day were used (11, 12).

Summary: Studies suggest that spirulina can lower triglyceride levels and levels of "bad" LDL cholesterol while increasing levels of "good" HDL cholesterol.

Spirulina protects the "bad" LDL cholesterol from oxidation

Fat structures in the human body are susceptible to oxidative damage. This is also known as lipid peroxidation and is a driving force in the development of many serious diseases (13, 14). One of the key steps in the development of heart disease, for example, is the oxidation of 'bad' LDL cholesterol (15). Interestingly, the antioxidants contained in spirulina appear to be particularly effective in reducing lipid peroxidation in humans and animals (16, 17). In a study of 37 people with type 2 diabetes, 8 grams of spirulina per day significantly reduced markers of oxidative damage. Spirulina also increased the levels of antioxidant enzymes in the blood (18).

Summary: Fat structures in the body can be oxidized and promote the progression of many diseases. The antioxidants contained in spirulina may help prevent this.

Spirulina may have anti-cancer effects

Some studies suggest that spirulina may have anti-cancer properties. Research conducted on animals suggests that spirulina may reduce the incidence of cancer and tumor size. The effects of spirulina on oral cancers have been particularly well studied. A study from India examined 87 subjects with precancerous lesions in the mouth, known as submucosal fibrosis. In the subjects who took 1 gram of spirulina per day for one year, it was observed that these lesions disappeared in 45% of the subjects, while this was only the case in 7% of the subjects in the control group (21). After these subjects stopped taking spirulina, half of them developed lesions again the following year. In another study of subjects with submucosal fibrosis, 1 gram of spirulina per day led to a greater improvement in symptoms than the drug pentoxyfillin (22).

Summary: Spirulina may have anti-cancer effects and appears to be particularly effective in a type of precancerous lesion known as submucosal fibrosis.

Spirulina could lower blood pressure

High blood pressure is a primary driving force in the development of many serious diseases including heart attacks, strokes and chronic kidney disease. While 1 gram of spirulina appears to be ineffective, a dose of 4.5 grams per day has been shown to lower blood pressure in people with normal blood pressure (10, 11). This reduction in blood pressure is believed to be due to an increase in nitric oxide production. Nitric oxide is a signaling molecule that helps blood vessels to relax and dilate (23).

Summary: A higher dose of spirulina could lead to lower blood pressure levels.

Spirulina can reduce the symptoms of allergic rhinitis

Allergic rhinitis is characterized by inflammation of the nasal passage. It is triggered by environmental allergens such as pollen, animal hair or wheat dust. Spirulina is a popular alternative treatment for symptoms of allergic rhinitis and there is evidence that it may actually be effective in this regard (24). In a study of 127 subjects with allergic rhinitis, 2 grams of spirulina per day dramatically reduced symptoms such as runny nose, sneezing, nasal congestion and itching (25).

Summary: Spirulina supplements are very effective for allergic rhinitis and can reduce many symptoms.

Spirulina could help with anemia

There are different forms of anemia. The most common form is characterized by a reduction in hemoglobin, or the number of red blood cells in the blood. Anemia is quite common in older adults and can lead to persistent feelings of weakness and fatigue (26). In a study of 40 older people with a history of anemia, spirulina supplements were found to increase red blood cell hemoglobin levels and improve immune function (27). However, it should be kept in mind that this was only one study. Further research is needed before recommendations can be made.

Summary: One study suggests that spirulina may reduce symptoms of anemia in older adults. However, further research is needed.

Spirulina could increase muscle strength and endurance

Exercise-induced oxidative damage is a major contributor to muscle fatigue. Certain plant foods have antioxidant properties that may help athletes and physically active people minimize this damage. Some studies suggest that spirulina may improve muscle strength and endurance. In 2 studies, spirulina increased endurance and significantly delayed the onset of fatigue (28, 29).

Summary: Spirulina could be beneficial for athletes as it can increase endurance and muscle strength.

Spirulina could improve blood sugar control

Studies conducted with animals link spirulina to significantly lower blood sugar levels. In some cases, spirulina showed a better effect than popular diabetes medications including metformin (30, 31, 32). There is also evidence that spirulina may also be effective in this regard in humans. In a two-month study of 25 subjects with type 2 diabetes, 2 grams of spirulina per day led to an impressive reduction in blood glucose levels (9). The HbA1c value - a marker for long-term blood glucose levels - fell from 9% to 8%, which is substantial. Studies have concluded that a 1% reduction in this marker can reduce the risk of diabetes-related death by 21% (33). However, this study was of short duration and involved a relatively small group of subjects. Further research is therefore needed.

Summary: There is evidence that spirulina has benefits for people with type 2 diabetes and can significantly reduce fasting blood glucose levels.

Side effects and disadvantages

Although spirulina is generally considered safe, it may have some side effects and drawbacks, especially for people with certain medical conditions (35, 37) Here are some of the potential side effects and drawbacks of spirulina.

Spirulina may exacerbate autoimmune diseases

Because spirulina improves the function of the immune system, it could exacerbate certain autoimmune diseases such as lupus, multiple sclerosis and rheumatoid arthritis, in which the immune system attacks the body (35). Spirulina stimulates immune system function by boosting immune cells called natural killer cells. These killer cells attack perceived threats at the cellular level (43). Animal and human studies show that this effect can help slow tumor growth, improve resistance to disease and reduce inflammation (43, 44, 45, 46). However, boosting natural killer cells can worsen the condition of people suffering from autoimmune diseases. Spirulina supplements have also been linked to serious autoimmune reactions affecting the skin and muscles, although these reactions are very rare (47, 48).

For this reason, people suffering from autoimmune diseases should avoid spirulina and other algae products (35).

Spirulina could slow down blood clotting

Spirulina has an anticoagulant effect, which means that it can thin the blood and increase the time it takes for blood to clot (35, 49). However, blood clotting also prevents more severe bleeding and the formation of hematomas after injuries (50).

For people taking blood-thinning medication or suffering from blood clotting disorders, spirulina could be dangerous as it reduces the blood's ability to clot and could lead to more severe bleeding (35).

Although some studies suggest that spirulina does not affect the time it takes for blood to clot, little is known about this effect in people taking blood-thinning medication (51, 52). For this reason, spirulina supplements should be avoided if you suffer from a blood clotting disorder or are taking blood-thinning medication.

Other disadvantages of spirulina

Some people may have an allergic reaction to spirulina. In rare cases, these reactions can be fatal (53). According to one study, people with other allergies have a higher risk of allergic reactions to spirulina. For this reason, people with allergies should avoid spirulina supplements or consult their doctor before using them (21). Spirulina and other algae also contain phenylalanine, a compound that people suffering from phenylketonuria should avoid (35).

Some other mild side effects of spirulina can include nausea, insomnia and headaches. Despite this, spirulina is considered largely safe and most people do not experience any side effects when taking spirulina (35).

Spirulina can be contaminated with toxins

Wild spirulina has a significant risk of contamination. The algae may contain toxins when grown in waters contaminated with heavy metals, bacteria or harmful particles known as microcystin (35).

Microcystin is produced by blue-green algae as a defense mechanism against predators. When consumed in large quantities, they are harmful to the liver (38). Spirulina supplements contaminated with microcystin have been found in Italy, North America and China and these compounds are a serious cause for concern due to their liver-damaging effects (39, 40, 41).

Spirulina grown in a controlled environment contains lower levels of microcystin, as scientists have developed methods to remove this compound and limit its production (41, 42).

Summary: Spirulina can be contaminated with harmful compounds that can thin the blood and exacerbate autoimmune diseases. In addition, some people may be allergic to spirulina.

How to avoid side effects of spirulina

Since spirulina may have some side effects, especially for certain populations, it is best to consult your doctor before taking spirulina.

Doses of spirulina used

A standard dosage of spirulina is 1 to 3 grams, but dosages of up to 10 grams per day have also been used.

Conclusion

Spirulina is a cyanobacterium, often referred to as blue-green algae, that is surprisingly healthy. It can improve blood lipid levels, suppress oxidation and lower both blood pressure and blood sugar levels.

Although more research is needed to prove all the benefits of spirulina beyond doubt, spirulina may be one of the few superfoods worth its salt.

Even though spirulina is widely considered safe, it does have some potential side effects. Some supplements may be contaminated with toxins and in addition, this algae can aggravate autoimmune diseases, thin the blood and cause allergies in some people.