Spirulina – Benefits, Lies, Dosage and Properties


Spirulina as a dietary supplement: the benefits of spirulina

Spirulina is a spiral algae that has existed for 3 billion years.

Low in calories, it contains a large amount of proteins, antioxidants (carotenoids, phycocyanin) and gamma-linolenic acid (from the omega-6 family). Research highlights the antioxidant, anti-diabetic and immunostimulatory properties of spirulina, as well as its ability to reduce blood lipid levels. Having stimulating effects, food supplements of spirulina should not be consumed in the evening. If you suffer from phenylketonuria, you must consult your doctor before starting a cure.

Spirulina dosage

  • There is insufficient data to suggest a therapeutic dosage. During clinical trials, the dosage varied from 1 g to 1.4 g two to three times a day for the following indications: type 2 diabetes, high cholesterol and nasal allergies. Regarding weight loss, 200 milligrams of oral spirulina tablets three times a day have been used.
  • It is recommended to gradually increase the doses, starting with a dose of 1 g per day during the first week.

There are insufficient data to recommend the use of spirulina in children.

Description of spirulina

The spirulina is a seaweed that has existed for more than 3 billion years. So named because of its spiral shape, it belongs to the family of cyanobacteria or blue-green microalgae. There are almost 1,500 species of blue algae, and 36 species of spirulina are edible. The main species currently available on the market is Spirulina platensis. First cultivated mainly in California and Hawaii, spirulina is now produced in a controlled way everywhere in the world where the climate allows it: Chile, China, Cuba, India, West Africa, Greece (in geothermal greenhouses), etc. Commercially, spirulina is generally in the form of a dehydrated blue-green powder, in bulk or in capsules.

Nutritional composition. The spirulina, low in calories, contains a wealth of nutrients in a very small volume (partial list below). Its content can however vary according to its geographical origin, but also according to the culture, drying and grinding processes.

The spirulina contains 55% to 70% of protein of excellent quality (proportion of amino acids and optimal digestibility), i.e. from 2.5 g to 3.5 g of protein per 5 g of powder.

The spirulina is an exceptional source of various carotenoids (mainly beta-carotene, but also cryptoxanthin, lutein, zeaxanthin, etc.), i.e. around 22 mg / 5 g. In particular, it provides an astronomical quantity of beta-carotene, ie from 12,000 IU to 25,000 IU per 5 g of powder.

It is an excellent source of iron, from 3 mg to 8 mg per 5 g.

It contains a significant amount of gamma-linolenic acid (40 mg to 50 mg / 5 g), an unsaturated fatty acid from the omega-6 family1. To find out more about omega-6, see our Essential fatty acids sheet.

In addition, spirulina is rich in phycocyanin, the only natural blue pigment that can serve as a food coloring and to which we attribute significant antioxidant activity. It also contains chlorophyll and small amounts of several minerals.

This is why we often talk about this alga as ” superfood “.

History of Spirulina

When Europeans landed in Central America, they discovered that the Aztecs were drawing from the large Texcoco lake, located near Mexico City, a kind of blue “mud” with high nutritional value, the tecuitlatl or spirulina. In Africa, certain peoples of the Sahara have harvested for a very long time, in Lake Chad, a similar substance, the dihe, which is especially consumed by pregnant women and during periods of food shortage.

Malnutrition. Like the spirulina is very rich in nutrients and can be produced locally, it is used to fight malnutrition in many countries. Production “farms” have been set up, notably in India, Peru, Togo, China and Vietnam. Pilot projects led by IIMSAM, an organization recognized by the United Nations, are also underway in many countries. According to the authors of a summary on nutritional rehabilitation, the research published to date on spirulina and malnutrition has significant weaknesses, but several trials have given positive results.

During the 1970s, the spirulina has become popular in industrialized countries as a health food or dietary supplement. So much so that a number of “urban legends” began to circulate about it. For example, the claims about weight loss and attention deficit hyperactivity disorder (ADHD) are not supported by any evidence. These uses are also not based on a practice of traditional medicine, which is essentially based on the fact that this alga is a food very rich in nutrients.

Spirulina research

Several animal tests have shown that the spirulina has antioxidant, immunostimulatory, anti-diabetic properties and can reduce blood lipid levels. However, to date, despite the allegations of certain producers and distributors, the data supporting its effectiveness in humans are insufficient. Indeed, although it has been the subject of several clinical trials, many of them are small (30 subjects or less) and their methodological quality often leaves something to be desired.

Reduction of blood lipids. In this regard, results from animal and human trials are promising, but not convincing enough to conclude that spirulina is effective. Indeed, 7 trials, counting few subjects (40 or less) and whose methodology often leaves something to be desired, indicate that the spirulina may slightly lower blood lipid levels. A study published in 2008, and of good methodological quality, focused on more subjects: 78 healthy people over 60 took either a placebo or 8 g of spirulina per day for 4 months. Compared to placebo, spirulina slightly reduced the cholesterol levels of the participants, particularly that of women. Another study confirms that spirulina (5g / day for 15 days) not only increases the levels of HDL cholesterol (called “good cholesterol”) but also decreases those of LDL cholesterol (“bad cholesterol”) and triglycerides. Better research is needed to confirm the effectiveness of spirulina in the treatment of high cholesterol.

Allergic rhinitis. A trial in Turkey involved 129 people with allergic rhinitis. Taking 2 g of spirulina per day, for 16 weeks, was much more effective than a placebo at reducing participants’ symptoms. The anti-inflammatory properties of spirulina (2 g per day for 12 weeks) may be responsible for the reduction of symptoms accompanying nasal allergies, as reported in a randomized double-blind study in patients with rhinitis allergic. Two other tests indicate that spirulina has a positive role on the immune system of the mucous membranes of the nasal passages.

Diabetes. Preliminary studies in people with type 2 diabetes report that a 2-month treatment with spirulina would reduce fasting blood sugar levels. Another study indicates that spirulina increases the effectiveness of insulin in diabetic patients with HIV. More studies are needed to confirm these results.

Immune system. Tests, mostly preliminary, indicate that taking spirulina may positively influence certain markers of immunity in healthy people or people with rhinitis.


In a preliminary trial of 37 subjects with diabetes, taking 8 g of spirulina for 12 weeks had no effect on the participants’ blood sugar levels. However, the treatment had a slight beneficial effect on blood triglyceride levels, as well as on certain markers of inflammation and oxidative stress.

During a study of poor methodological quality with people suffering from precancerous inflammation of the mucous membranes of the mouth (leukoplakia), there was significantly more healing in the treated group (1 g of spirulina per day for 1 year) than in the placebo group.

According to a trial of 16 untrained subjects, taking spirulina increased the resistance to effort by reducing the oxidative stress and aches of the participants after physical exercise. Another trial of 9 athletes training moderately indicates that 6 g of spirulina per day for 4 weeks increased their performance physical.

During a crossover preliminary test, the spirulina, at a rate of 3 g per day, did not reduce the symptoms of subjects suffering from chronic fatigue syndrome.

A trial in Israel involved 120 children suffering from a attention deficit disorder (TDHA). Compared to the placebo group, subjects treated with a complex containing 6 plants, including spirulina, have seen their attention span improved. However, this study does not provide information on the specific effect of the blue algae.

Claims about the effectiveness of spirulina – sometimes marketed as a vitamin-rich appetite suppressant – for reduce appetite and losing weight are based on a preliminary study lasting 4 weeks, in which 15 volunteers consumed 200 mg of spirulina per day. However, as the results of this trial are inconclusive and its methodological quality is poor, no conclusions can be drawn from it.

Eye disorders (blepharospasm). Giant blue-green algae may decrease eyelid spasms (blepharospasms), but more high-quality research is needed before a recommendation can be made.



  • Unlike other blue-green algae, the spirulina is not contaminated with toxins called microcystins. If the label of a product has a mention of the type “Blue-green algae”, “Blue-green superfood” without the word “spirulina” appearing there, it is probably another species of cyanobacteria, for example theAphanizomenon flos-aquae which can be contaminated.
  • Test on nearly 82 samples of Spirulina sold in Canada found that this alga is also not contaminated with toxoid-a, another dangerous toxin produced by certain algae.
  • Algae accumulate heavy metals such as lead, arsenic and cadmium when their growing environment is polluted. It is therefore recommended to opt for spirulina, the cultivation methods of which are strictly controlled: look for such indications on the product label, or, in case of doubt, contact the manufacturer.
  • Since spirulina can have a stimulating effect in some people, it is best not to take it in the evening.


  • None at current doses.
  • People suffering from phenylketonuria Spirulina should be avoided because, like all protein-containing foods, it contains phenylalanine.

Side effects

  • In some people, various symptoms such as gastrointestinal upset and headache can occur, especially when the starting dosages are too high. To avoid these symptoms related to the detoxifying properties of spirulina, start with 1 g per day for 1 week and gradually increase the dose over the following weeks.

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