Difference Between Chlorella and Spirulina

Key Difference – Chlorella vs Spirulina

Chlorella and spirulina are two edible microalgae which can be consumed as food as well as nutritional supplements, but ordinary consumers cannot understand and distinguish the difference between them, and they often use chlorella and spirulina, interchangeably. Both chlorella and spirulina belong to the genus of green unicellular algae and to the phylum of Chlorophyta. Although, equal in some organoleptic characteristics and growing conditions, spirulina and chlorella are absolutely two different varieties of algae that have numerous important characteristic traits. The key difference between them is that Chlorella is a green single-cell freshwater algae that contain a very strong concentration of peroxisome proliferator-activated receptors whereas Spirulina is a blue-green single-cell freshwater algae that contain protein, essential minerals and vitamins, trace minerals, fibre, nucleic acids, fatty acids, polysaccharides and antioxidant phytochemicals.

What is Chlorella?

Chlorella is a green single-cell freshwater algae that contain a very strong concentration of peroxisome proliferator-activated receptors. These receptors are known to regulate the human metabolism, strengthen the immune system and promote overall health. Chlorella is also rich in chlorophyll, fibre, protein, vitamins, minerals, amino and nucleic acids. Therefore, they are considered as valuable functional foods and available in both tablet and powder form.

Key Difference - Chlorella vs Spirulina

A microscopic view of the alga Chlorella.

What is Spirulina?

Spirulina is a blue-green single-cell freshwater algae that contain protein, essential minerals and vitamins, trace minerals, fibre, nucleic acids, fatty acids, polysaccharides and antioxidant phytochemicals. Spirulina is also low in calories and considered as a complete source of high quality protein, and it has recently been associated with significant weight reduction in the human body. It is also available in both tablet and powder form and sell as functional foods.

Difference Between Chlorella and Spirulina

What is the difference between Chlorella and Spirulina?

Chlorella and spirulina are rich in many bioactive phytochemicals and offer a wide array of health benefits when incorporated into the daily diet. In order to help you decide, how to differentiate the two algae, we have identified the following major differences under 8 categories:

Morphological differences between Chlorella and Spirulina

Spirulina: Spirulina is a spiral-shaped single-cell alga with no true nucleus. Spirulina is larger than chlorella. It has a soft cell wall and blue-green in colour.

Chlorella: Chlorella is a spherical-shaped single-cell alga with a nucleus. Chlorella is smaller than Spirulina. It has a hard cell wall. Chlorella is a green color alga.

Pigment Compounds 

Spirulina: Spirulina is rich in a unique blue-green pigment called phycocyanin pigment. Phycocyanin is a phytochemical that can prevent cancer and offers spirulina its distinctive blue-green hue. This pigment is a powerful antioxidant that helps to protect the tissues from free radicals. Therefore, spirulina nutritional supplements may strengthen the immune system, improve brain function and heart health, and decrease the risk of allergic reactions.

Chlorella: Chlorella contains ten times more chlorophyll pigment than spirulina. This pigment provides green plants and algae their color. It is a powerful antioxidant and disease preventing phytochemical, that contributes to clean and detoxify the liver and digestive tract and decreases harmful cholesterol levels in the human body. However, Chlorella does not contain phycocyanin and has no exact influence on inflammation.

Protein Content 

Spirulina: Spirulina contains more protein than chlorella. Thus, spirulina is considered as a good source of high quality protein and spirulina contains about 60% protein.

Chlorella: Chlorella is also recommended as an economical protein supplement to the daily human diet. But it contains 40% of protein which is less than Spirulina.

Both spirulina and chlorella are complete proteins comprising all essential amino acids. However, they contain fewer amounts of lysine, methionine and cysteine amino acid when compared to the animal proteins such as milk, meat and eggs.

Mineral Content 

Chlorella: Chlorella contains additional iron content than spirulina. It is also rich in potassium (K), calcium (Ca), chromium (Cr), copper (Cu), iron (Fe), magnesium (Mn), manganese (Mg), phosphorus (P), selenium (Se), sodium (Na), and zinc (Zn) compared to spirulina.

Fat Content 

Spirulina: Spirulina contains 7% of fat and it is a rich source of gamma-linoleic acid (GLA). GLA is considered as a healthy fat that is crucial for brain development and heart function. Spirulina also provides different healthy fatty acids such as alpha-linolenic acid, linoleic acid, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), stearidonic acid, and arachidonic acid. Based on its lipid profile, spirulina provides a small amount of Omega-3 fatty acids, but it is a rich source of Omega-6 fatty acids.

Chlorella: chlorella is rich in polyunsaturated fats. But research has not proven that it is a rich source of gamma-linoleic acid.

Health Benefits 

Spirulina: Administration of spirulina has been examined as a way to improve immune system function. According to the World Health Organization, spirulina is considered as an interesting food supplement for several reasons because it is rich in iron, protein and other phytochemicals. Thus, it is considered a very suitable food not only for children but also for adults to meet their basic nutrition requirements.

Chlorella: Chlorella is consumed as a health or food supplement predominantly in the United States, Canada and Japan. Chlorella comprises a distinct growth factor which can support the repair of nerve tissue damages. Thus, it is a perfect food supplement for individuals with degenerative brain and nerve disorders.


Spirulina: Spirulina can grow in natural water bodies such as freshwater ponds, rivers, and lakes that have a moderately high alkaline (high pH) content. Adequate temperatures and sunshine are essential to produce a good harvest. Harvesting and processing of spirulina is easier than chlorella.

Chlorella: Chlorella, is also grown in fresh water tanks and it, is more difficult to harvest and cultivate compared to spirulina. Furthermore, chlorella is usually more difficult to process than spirulina, because it has an indigestible hard cellulose wall. Therefore, chlorella has to go through a complex procedure to mechanically break down the cellulose wall and to produce bio available chlorella. Furthermore, this procedure is highly complex, and it requires expensive utensils. Thus, the cost of the production is eventually higher in the production of chlorella compared to the production of spirulina.


Spirulina: Spirulina has a perfectly digestible cellulose wall which is composed of muco-polysaccharides as a replacement for indigestible cellulose. Therefore, it is readily digested and absorbed by the human intestine.

Chlorella: Chlorella has an indigestible hard cellulose wall which can cause gastrointestinal discomfort in up to 20% of persons.

In conclusion, both spirulina and chlorella share many similar characteristics, while also supporting a specific set of valuable health benefits and nutrient content. We have attempted to understand the terms spirulina and chlorella in this article followed by a comparison to discover the key categories differentiating them in between.

Ciferri, O (1983). Spirulina, the edible microorganism. Microbiol. Rev., 47 (4): 551–78.
Colla, L. M., Bertolin, T. E. and Costa, J. A. (2003). Fatty acids profile of Spirulina platensis grown under different temperatures and nitrogen concentrations. Journal of biosciences, 59 (1-2): 55–9.
Stewart, I, Schluter, P. J. and Shaw, G. R. (2006). Cyanobacterial lipopolysaccharides and human health – a review. Environmental Health: A Global Access Science Source, 5: 7.
Image Courtesy
“Spirulina tablets” by Original uploader was Perdita at the English Wikipedia – Originally from the English Wikipedia; description page is/was here.(Public Domain) via Wikimedia Commons 
 “Chlorella” by VladiDamian – Own work. (GFDL) via Wikimedia Commons