What is the Difference Between Spirulina and Chlorella

The main difference between spirulina and chlorella is that spirulina is a multicellular, spiral-shaped, cyanobacteria, which grows naturally in warm freshwater lakes, natural springs, and saltwater, whereas Chlorella is a single-celled, spherical-shaped green alga, which grows in freshwater. Furthermore, spirulina lacks a cellulose cell wall, making it easy to digest while Chlorella contains a hard cellulose cell wall, making it indigestible. Also, Spirulina is rich in proteins, thiamine, riboflavin, iron, and copper while Chlorella is rich in chlorophyll, calories, fat, omega-3 fatty acids, antioxidants, provitamin A, riboflavin, iron, zinc, and magnesium.  

Spirulina and Chlorella are two types of microalgae that can be grown in freshwater. They are the most popular algae supplements due to their impressive nutrient profiles. 

Key Areas Covered 

1. What is Spirulina
     – Definition, Characteristics, Importance
2. What is Chlorella
     – Definition, Characteristics, Importance
3. What are the Similarities Between Spirulina and Chlorella
     – Outline of Common Features
4. What is the Difference Between Spirulina and Chlorella
     – Comparison of Key Differences

Key Terms 

Chlorella, Microalgae, Proteins, Spirulina, Supplements

What is the Difference Between Spirulina and Chlorella - Comparison Summary

What is Spirulina 

Spirulina is a spiral-shaped, multi-celled organization of cyanobacteria. Generally, the two species of spirulina include Arthrospira platensis and A. maxima. Moreover, they grow in freshwater as well as in relatively high alkaline water. Also, moderate temperature and sunshine are two important factors for growth. They are cultivated worldwide as a whole food or dietary supplement due to the richness of nutrients. Thus, the lack of a cellulose cell wall makes it easy to digest spirulina.

Difference Between Spirulina and Chlorella

Figure 1: Spirulina

Furthermore, spirulina is popular as a complete source of proteins, ranging from 55-77%. It supplies rarest essential fatty acids, gamma-linolenic acid (GLA), which is difficult to find in food. Usually, it is well known for its anti-inflammatory benefits. Spirulina also contains phycocyanin, a unique antioxidant, preventing cancer. Especially, it is rich in beta-carotene as well. Furthermore, spirulina contains a higher amount of vitamins A, B, C, E, and K, as well as the minerals potassium, calcium, chromium, copper, iron, and magnesium. 

What is Chlorella  

Chlorella is a unicellular green alga with a spherical shape. Moreover, it was the first form of plant with a well-defined nucleus. Generally, Chlorella is extremely small and grows in freshwater. It is also rich in chlorophyll-a and -b in its chloroplast. However, this microalgae contains an indigestible cellulose wall, which has to be broken down while processing as a supplement. 

Main Difference - Spirulina vs Chlorella

Figure 2: Chlorella vulgaris

Moreover, chlorophylls in Chlorella serve as a powerful antioxidant and a cleansing agent, detoxifying the liver and digestive tract. They chelate heavy metals, including mercury, lead, and aluminum. A unique Growth factor that occurs in Chlorella helps to repair damages in nerve tissue, boosting the immune system. Furthermore, Chlorella is rich in antioxidants, including beta-carotene, alpha-carotene, and lutein. Also, it is rich in vitamins B, C, D, E, K, and the minerals phosphorus, calcium, zinc, magnesium, and iron.  

Similarities Between Spirulina and Chlorella  

  • Spirulina and Chlorella are two types of freshwater microorganisms. 
  • They are rich in chlorophyll and nutrients.  
  • They are also rich in polyunsaturated fatty acids such as omega-3 and omega-6.  
  • Moreover, they are the most popular algae supplements in the market.  
  • Both are touted as superfoods;  they are good sources of protein and amino acids.  
  • Generally, they are available as capsules, extracts, powder, and tablet supplements.  
  • They have an impressive nutritional profile and similar health benefits.  
  • Furthermore, they may lower the risk of heart disease while improving blood sugar levels. 

Difference Between Spirulina and Chlorella 


Spirulina refers to filamentous cyanobacteria which form tangled masses in warm alkaline lakes in Africa and Central and South America while Chlorella refers to a common, single-celled green alga in both terrestrial and aquatic habitats, turning stagnant water an opaque green.  


Moreover, spirulina belongs to the family Microcoleaceae under the phylum Cyanobacteria while Chlorella belongs to the family Chlorellaceae under the phylum Chlorophyta. 


Another difference between spirulina and Chlorella is that Spirulina belongs to the genus  Arthrospira while Chlorella belongs to the genus Chlorella. 


Furthermore, spirulina naturally grows in warm, freshwater lakes, natural springs, and saltwater while Chlorella mainly grows in freshwater. 

Cellular Organization 

Spirulina is a multicellular, spiral-shaped, cyanobacteria while Chlorella is a single-celled, spherical-shaped, green algae. 


Besides, spirulina can be 100-times larger than Chlorella, which can be up to 2 to 10 μm in diameter. 


While spirulina contains less amount of chlorophyll, Chlorella contains ten times higher chlorophyll content. 

Cellulose Wall 

Also, spirulina lacks a cellulose cell wall, making it easy to digest, while Chlorella contains a hard, cellulose cell wall, making it indigestible. 


Spirulina is lower in calories (81 calories per ounce) while Chlorella is higher in calories (115 calories per ounce). 


While spirulina is lower in fat (2 g per ounce), Chlorella is rich in fat (3 g per ounce). 

Essential Fatty Acids 

Spirulina is rich in omega-6 fatty acids, while Chlorella is rich in omega-3 fatty acids.  


While spirulina contains a comparatively lower amount of antioxidants, Chlorella is rich in antioxidants. 


Spirulina may be rich in proteins while Chlorella contains comparatively a lower amount of proteins. 

Vitamins and Minerals 

Generally, spirulina is rich in thiamine, riboflavin, copper, and iron while Chlorella is rich in provitamin A, riboflavin, magnesium, iron, and zinc. 


The dosage of spirulina ranges from 1-8 g while the dosage of Chlorella ranges from 2-5 g. 


Spirulina is a cyanobacterium that has a spiral-shaped multicellular organization. It contains a lesser amount of chlorophyll. Meanwhile, it does not contain a cellulose wall. Therefore, it is easy to digest and rich in proteins, thiamine, riboflavin, iron, and copper. In contrast, Chlorella is a unicellular green alga with a spherical shape. It is rich in chlorophyll, calories, fat, omega-3 fatty acids, antioxidants, provitamin A, riboflavin, iron, zinc, and magnesium. Due to the presence of a cellulose wall, Chlorella is difficult to digest. Although both of them are algal supplements, the main difference between spirulina and Chlorella is their structure and benefits. 


1. Cox, Lauren. “Spirulina: Nutrition Facts & Health Benefits.” LiveScience, Purch, 7 Feb. 2018, Available Here.
2. “Chlorella: Uses, Side Effects, Interactions, Dosage, and Warning.” WebMD, WebMD,  Available Here.

Image Courtesy:

1. “Spirulinapowder400x” By John Alan Elson (CC BY-SA 3.0) via Commons Wikimedia   
2. “Chlorella vulgaris NIES2170” By ja:User:NEON / User:NEON_ja – Own work (CC BY-SA 3.0) via Commons Wikimedia   

About the Author: Lakna

Lakna, a graduate in Molecular Biology and Biochemistry, is a Molecular Biologist and has a broad and keen interest in the discovery of nature related things. She has a keen interest in writing articles regarding science.

Leave a Reply