Spirulina & Chlorella Health Benefits

Spirulina and Chlorella have become incredibly popular in the nutrition and supplement world, and are often marketed as ‘natures multivitamin’, but how much of this is true and what...

Spirulina and Chlorella have become incredibly popular in the nutrition and supplement world, and are often marketed as ‘natures multivitamin’, but how much of this is true and what is spirulina? This article will explain what spirulina and chlorella are, and investigate their nutritional content and health benefits.



Spirulina belongs to a group of green algae called cyanobacterium, which like plants, obtain energy from the sun via photosynthesis. It grows in fresh water in tropical climates, and requires a high pH to thrive. Records of spirulina being consumed as a food go as far back as the early 1500s where it was eaten in a cake form, not too dissimilar to the supplement form we find it in today. This indicates that spirulina is very safe to consume in large quantities, indeed, in human trials people have consumed over 800mg/kg body weight  of spirulina (which equates to 560g for the average male) and seen no ill effects.

What Is Spirulina?

Image Courtesy of SweetOnVeg

Nutritionally, spirulina is thought of as a ‘complete’ food. With regards to macro-nutrients, spirulina consists of approximately 70% protein, 20% carbohydrates and 7% fats by weight. The protein contains all essential amino acids, making  it a source of very high quality protein, and better quality than most other vegetable sources such as legumes. The majority of fatty acids in spirulina are omega-3 fatty acids (EPA, DHA and ALA), which are essential for proper nervous, brain, joint and cardiovascular health, and must be obtained from our diet as we cannot synthesis them in our body. It also contains Gamma-linoleic acid (GLA) which supports the immune system and helps to control inflammation. Approximately 20% of the remaining weight of spirulina is made up of carbohydrates, which are predominantly complex carbohydrates and fibre – sugars account for approximately 3% of spirulina. This is ideal for humans, as complex carbohydrates are a much more favorable energy source than sugars.

Spirulina also contains a broad spectrum of vitamins and minerals, and is particularly high in many B vitamins, potassium, calcium, copper vitamin K and vitamin C, although others are also found in significant quantities. 100g of spirulina will provide you with:

  • 12% your RDA of calcium
  • 39% your RDA of potassium
  • 305% your RDA of copper
  • 25% your RDA of vitamin K
  • 17%  your RDA of vitamin C

Although high in many B vitamins, vitamin B12 (cobalamin) is inactive and biologically insignificant in spirulina supplements. This is of concern, as many companies market spirulina to vegans as being a good source of vitamin B12, which is not true.



Chlorella belongs to a group of blue-green algae called chlorophyta, which are single cell organisms that grow in fresh water. They require very little nutrients to thrive, and like many algae and spirulina, produce energy through photosynthesis and so are very high in a compound called chlorophyll (the green pigment in plants) which is required for the photosynthesis process. There has been concern that the proteins on the cell wall of chlorella may cause an immune reaction similar to an allergic reaction, but there is no evidence of this, and large quantities have been consumed with no adverse effects.

Chlorella contains less protein than spirulina, with approximately 45% of its weight being protein, but it is still of a high quality, and provides a complete range of amino acids. This still makes it a better quality protein source than most vegetables which usually contain no more than 30% protein, and is usually of a low quality. Up to 20% of the weight of chlorella is fatty acids, the most abundant being omega-3s (especially ALA) and omega-6’s, which are well recognized for their health benefits.  Another 25% of chlorella is made up of carbohydrates, and of this 5% is insoluble fibre, which is good for your digestive system. The macro-nutrients of chlorella are much more balanced than that of spirulina, making it more of a complete food. However, for those who have low protein diets such as vegans, siprulina may still be a preferable option.

10% of chlorella is made up of a variety of vitamins and minerals. This is a much higher percentage than that of spirulina, and like spirulia, it contains a broad spectrum of many vitamins and minerals. Chlorella is most abundant in zinc, phosphorus, calcium, vitamin A and a number of B vitamins. 100g of chlorella will provide you with:

  • 8666% your RDA of vitamin B12
  • 13% your RDA of vitamin C
  • 27% your RDA of calcium
  • 105% your RDA of magnesium
  • 645% your RDA of zinc

The vitamin B12 found in chlorella is in a biologically active form, which our body can uses – making it valuable for vegans who may struggle to obtain vitamin B12 form their diet. However, in order to obtain all the nutrients from chlorella the cell walls must be broken down prior to consumption, because our body is unable to digest or breach the cell wall itself.


What is Spirulina & Chlorella? – Summary

Both spirulina and chlorella do contain an abundance of nutrients, and are an excellent source of essential nutrients which are not abundant in other plants, which is particularly relevant for people who have dietary restrictions on protein and/ or vitamin B12, such as vegans. Spirulina is a superior source of protein to chlorella, but chlorella contains more healthy fats and contain vitamin B12 in a biologically relevant form.  It is important to note that spirulina doesn’t contain a hard cell wall, where as chlorella does, which requires breaking before consumption in order to absorb the nutrients.

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