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Spirulina Health Benefits, Side Effects, and Nutrition Facts

Updated on October 5, 2016

Spirulina Health Benefits: Fact or Fiction?

There are a large number of reported spirulina health benefits, and it is increasing in popularity as a supplement and food source, even being branded one of the 'super-foods' and 'future-foods' by many companies. NASA, the World Health Organization, and several governments of developing nations have shown an interest in it. But as with many supplements and less well known food sources, it is not always easy to distinguish scientifically proven fact from optimism and clever marketing.

This article discusses some of the possible health benefits, current scientific evidence, nutrition facts, and possible side effects of using spirulina as a supplement. Spirulina is expensive, so if you are going to invest your hard-earned cash in it, make sure you read this article to see if it is really worth it.


What Is Spirulina?

Spirulina is an edible blue-green micro-alga which grows wild in Africa, Asia, Central and south America. It is made into supplements also, as seen in the picture here. There are technically two different kinds: Arthrospira Platensis and Athrospira Maxima. These two species were re-classified as arthrospira. However, the general word spirulina has stuck as it has been used for so long.

It has been used as a food for centruries by South Americans and North Africans. It grows wild in fresh water lakes, though has also been grown in processing plants in some countries since the late 1960s. It has an adaptable nature and is known for its survival ability—perhaps another reason for its reputation.

Nutrition Facts

To understand the reason why there are so many reported Spirulina health benefits, it is worth looking at its nutritional content, as this is where the claims to it being a super-food are based: the rich and varied nutritional content.

According to the US National Agricultural Library's National Nutrient Database for Standard Reference, the nutritional content of 100g of dried Spirulina is listed in the table below.

Please bear in mind when looking at the table that the nutritional values are listed per 100 grams. In reality, you would be eating no more than 6-10 grams of Spirulina per day if taking it daily, with the occasional possible therapeutic booster dose of around 16 grams.

Spirulina's Nutritional Content

VITAMIN E (alpha-tocopherol)
VITAMIN K (phylloquinone)

Spirulina Facts: Health Benefits Examined

1. High Protein Content

One of the most frequently advertised health benefits of spirulina is the protein content. While it does contain a lot of protein, and is also a complete protein containing all essential amino acids, a normal amount of spirulina one takes is only around 6-10 grams a day. So even though the protein content of 100 grams in this table (57.47g) looks like a good amount, you would actually struggle to get more than 5 grams of protein a day from spirulina. Every little bit helps, of course, especially if you have a special diet like being vegetarian or vegan. But solely used as a protein source it would be very expensive. If you eat a normal diet you can obtain more protein per serving and per gram from some foods such as chicken, eggs, tuna or soy beans at a much lower price. But for some people, it may well be a valid and useful extra source of protein, as long as they do not rely on it.

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2. Rich Source of Vitamin B-12

Another of the spirulina's health benefits is supposed to be its high B-12 content, which is a vitamin that vegetarians and vegans for example can sometimes struggle to get in sufficient quantities. In the table above though you can see spirulina is listed as having zero B-12 content. This is because the scientific community regards the B-12 found in it to be an unreliable source. It is seen as being in an analogue form which humans are not able to metabolize, and so can not use. Another theory is that it does contain useable B-12 but it is because the supplements are contaminated by insect matter. This would only be in forms that have not been rigorously tested though, and these two arguments contradict one another. At the end of the day though, the scientific community is generally in agreement that spirulina should not be seen as containing vitamin B-12 that humans can use. So yes, it does contain a lot of B-12, but it is not of any use to humans. So some companies may well be misleading the public.

3. Spirulina Is High in Vitamins and Minerals

A general claim is that spirulina contains a wide and substantial variety of different vitamins and minerals. Whilst this is undeniably true, the question is though, does it contain vitamins and minerals in quantities and forms that you cannot easily get from a normal balanced diet containing plenty of vegetables and fruit? The answer it would appear, is no. There is nothing contained in spirulina that is not readily available in other plants, vegetables and fruits, and is often more easily digested as well. Perhaps if you are not able to access fresh fruit and vegetables in sufficient amounts, but spirulina is readily available it may be useful, and it may well again be a useful extra to a normal diet as it does have an undeniably rich vitamin and mineral content - at an expense.

Could you get the same vitamins and minerals with a balanced diet rather than by taking spirulina supplements? It appears that the answer is no.
Could you get the same vitamins and minerals with a balanced diet rather than by taking spirulina supplements? It appears that the answer is no. | Source

4. Spirulina Helps Prevent Cancer

Spirulina contains a good amount of anti-oxidants such as beta-carotene, which forms part of the argument that one of the most important claims: that is is useful for cancer prevention. However, again there is no proof that even beta-carotene is effective in preventing cancer. One study even claims that in smokers and former smokers, high beta-carotene supplementation can increase the risk of lung cancer. The general claims made for spirulina's cancer fighting properties are just not backed up by science. The National Cancer Institute, for example, discusses how anti-oxidant research has been inconclusive in determining its cancer fighting properties.

5. Other Health Claims

There is a whole host of other nutritional and health benefits that are sometimes claimed for spirulina. It is beyond the scope of this article to look into every one in detail, but here are some of the other benefits it is reported to have:

  • Helps encourage weight loss
  • Leads to increased mental alertness and concentration
  • Has a detoxifying effect in the body - fighting toxins and helping to purify the liver, and helping remove toxic metals like Lead and Mercury from the body
  • Helps lower cholesterol
  • Helps fight viral infection
  • Increases the body's ability to produce red blood cells
  • Helps balance blood sugar issues
  • Useful for treating radiation sickness
  • Strengthens the nervous system, and the immune system
  • Helps wounds to heal quicker
  • Useful for body-builders and those involved in exercise due to its ability to aid recovery and cell repair and growth.
  • It can help malnourished people to regain health again.

How many of the above points are true or not remains to be proven be peer-reviewed research.

Always check where your spirulina came from.
Always check where your spirulina came from. | Source

Is Spirulina Safe to Use?

Despite the disputes we make here to some claims about spirulina, this supplement is generally well tolerated and safe for humans. Studies have been done where animals and humans have been given massive doses of spirulina and no toxic effects were reported. There are some possible side effects, but they are usually quite mild and found mostly in people with an underlying condition. The possible side effects that have been reported, though rarely, are:

  1. Fever - usually associated with rising body temperature due to the digestion of protein.
  2. Digestive problems - some people may have difficulty digesting spirulina, leading to excessive gas and abdominal pain. This is often countered by ensuring you drink plenty of water after drinking spirulina or along with it.
  3. Edema - possible swelling of body parts due to already weakened or malfunctioning kidneys struggling to cope with the influx of vitamins, minerals and proteins contained in spirulina.
  4. Mild body rash or itching in people who prove to be allergic to spirulina.
  5. Dizziness, tiredness or hunger in people who suffer from anemia.

There is also the possibility that you may purchase spirulina from a disreputable source that has not harvested it in a controlled setting and it is contaminated. Some supplements have been found to be contaminated with microcystins which can lead to gastrointestinal problems and even liver cancer. In China the government announced that lead, mercury, and arsenic was widely found in spirulina supplements. So always check that the spirulina you are buying is from a recommended seller, and if buying online, be wary where you buy from.

Conclusions About Spirulina's Claimed Benefits

Whilst there is no doubting that spirulina is very rich nutritionally, the problem seems to lie in exaggerated and misleading claims made by sellers and advertisers. When there is clever, but dubious, marketing involved which informs the potential buyer that their supplement contains 'more protein than any other food' or the 'highest source of B-12 in the plant kingdom', then they are just not telling the whole story - such as how much of it you can actually take per day, and so how much nutritional content you would actually receive. And whilst there may well be many health benefits, there is just not enough scientific evidence at the moment to confidently endorse spirulina as a 'miracle super-food'.

My advice is that if you are willing to spend large amounts of money on spirulina in faith just to see if you feel any benefits from it, or as an additional part of a good diet, then that is your choice. But if it seems expensive to you, and you are struggling to pay for it, then perhaps you may be better off doing a little more research into how you can have a generally well-balance diet.

Certainly for people who cannot access enough food types to maintain a normal and healthy balanced diet, vegetarians, vegans, and other people who have special dietary requirements, it may be a good additional source of protein, but I would not recommend attempting to rely on it as the main source of protein in any diet by taking more than the advised daily amount, and I would not suggest spending large amount of money on spirulina if you cannot afford it.

As with many things, do your own research and don't be fooled by very clever advertising. Spirulina health benefits are real, but at a cost.

A video showing Spirulina processing in detail

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.


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    • profile image


      5 years ago

      Just a few minutes on pubmed doing a search for spirulina, as a keyword search, shows how weak this article is. And here are some recent reviews of human clinical trials:

      A PDF which I couldn't cut and paste, which you can google as:

      "The beneficial effects of spirulina focusing on its

      immunomodulatory and antioxidant properties"

    • Ethan Green profile imageAUTHOR

      Ethan Green 

      6 years ago from England

      I'm not sure where you read that the nutrient levels are negligible?

    • profile image


      6 years ago

      Interesting that the article claims the nutrient and protein levels in spirulina are so low that they are negligible, yet simultaneously reports a side effect of kidney damage do to the influx of vitamins, minerals and proteins. Hmmmm.

    • Ethan Green profile imageAUTHOR

      Ethan Green 

      8 years ago from England

      What was the adverse reaction you experienced?

    • travel_man1971 profile image

      Ireno Alcala 

      8 years ago from Bicol, Philippines

      I was able to sold boxes of spirulina during my radio days (early 90s) and I received huge commission from it.

      I used to take it, too,for cleansing. Unfortunately, I had to discontinue it because of the adverse reaction.

      I don't know,I still had to hear the advice of a friend-doctor.

    • Ethan Green profile imageAUTHOR

      Ethan Green 

      8 years ago from England

      Thank you for your comment, and compliment, tobusiness. You are right about the nutritional values being found in 'normal' food, but it is an interesting food source nonetheless.

    • tobusiness profile image

      Jo Alexis-Hagues 

      8 years ago from Lincolnshire, U.K

      A very well constructed informative hub. I haven't heard of this supplement before but it seem that most of the nutritional values can be found in most foods just a case of balancing what we eat. However it's interesting to know the facts. Thank you for sharing.


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