Chlorella (green algae)

What Is It?
Health Benefits
Dosage Information
Guidelines for Use
General Interaction
Possible Side Effects
Evidence Based Rating Scale


What Is It? 

Chlorella is a genus of single-celled freshwater green algae (also known as seaweed) once believed to be a “superfood” because it is high in protein and other essential nutrients. Chlorella contains the green photosynthetic pigments chlorophyll-a and –b in its chloroplasts, which absorb sunlight and use it in conjunction with water and carbon dioxide to make sugars. Chlorella quickly multiplies through photosynthesis, making it a highly efficient crop (1).

Because of the photosynthetic efficiency of Chlorella, scientists in the late 1940s and early 1950s believed it would be the answer to world hunger – providing large amounts of high quality foods at a relatively low cost. They also hoped to add a powder form of Chlorella to foods as a way to fortify them with vitamins and minerals. However, experimental research offered disappointing results. Chlorella, they discovered, only reaches its nutritional potential in highly modified artificial situations, such as requiring artificial light, carbonated water and an expensive harvesting process. It was also discovered that human and animals cannot digest Chlorella in its natural state. After these findings, Chlorella lost commercial and scientific interest, though it occasionally is still marketed as a “superfood.” (2)

 Health Benefits 

Chlorella is a good source of protein, nucleic acids, fiber, vitamins and minerals. It has been used orally for cancer prevention, stimulating the immune system, improving response to flu vaccine, preventing colds, to protect the body from toxic metals such as lead and mercury, and to slow aging. Other reported benefits include increasing healthy normal flora in the gastrointestinal tract which improves digestion, and helping prevent bad breath and constipation. Topical treatments of Chlorella has been used to treat ulcers, post-radiation dermatitis, the precancerous condition leukoplakias, and the sexually transmitted disease trichomoniasis. 

Specifically, Chlorella may help to: 

Treat chronic illnesses such as fibromyalgia, hypertension and ulcerative colitis. Preliminary evidence shows the high concentration of nutrients in Chlorella provide improvements in symptoms, relief of pain and improvement in quality of life in patients with fibromyalgia, hypertension and ulcerative colitis. A 2001 review of studies at Virginia Commonwealth University’s Medical College of Virginia proved the need for further research into the healing powers of Chlorella. The studies reviewed included double-blind, placebo-controlled, randomized clinical trials in which 55 patients with fibromyalgia, 33 with hypertension, and 9 with ulcerative colitis received two commercial Chlorella products – one 10 g tablet and 100 mL liquid dose – every day for two to three months. Scientists found that supplementation with Chlorella may reduce high blood pressure, lower serum cholesterol levels, accelerate wound healing and enhance immune function. (3) 

Better tolerate chemotherapy and radiotherapy in patients with glioma. While Chlorella doesn’t seem to prevent tumor progression or survival from glioma, a tumor in the nervous system that affects the brain or spinal cord, preliminary evidence suggests the immune-enhancing properties of the algae help patients better tolerate therapy treatments. (4) 

Improve response to the flu vaccine. Recent in vitro studies have confirmed the potential of an extract of Chlorella, specifically ONC-107 (Respondin), to boost antibody response to the flu vaccine. (5)  

Prevent bad breath. Chlorophyll, the chemical that gives Chlorella its green color, is one of nature’s most potent breath fresheners. Swishing and then swallowing a chlorophyll-rich drink containing chlorella might help prevent bad breath.



  • liquid
  • capsules
  • powder
  • enriched food products


Dosage Information 

  • For leukoplakia: 1 gram/day
  • For health maintenance: 3-5 grams/day
  • As a significant part of the diet: 6-10 grams/day
  • To build the immune system: 11-14 grams/day
  • As a primary source of protein: 12-19 grams/day
  • Heavy metal detoxification: 20-30 grams/day
  • To prevent bad breath: Swish a chlorophyll-rich drink containing Chlorella in your mouth, then swallow.
  • To improve tolerability of chemotherapy and radiotherapy: Up to 20 g tablet plus 150 mL liquid extract daily. 

Guidelines for Use 

Because it contains whole algae, Chlorella is extremely perishable. It should be stored properly without any UV light exposure at cool temperatures and in an oxygen-free environment. 

Chlorella acts to detoxify impurities from your body, so you may experience a period of discomfort as they are “flushed” out. Begin treatment gradually over the first few days and build up to the recommended dosage. Chlorella is best taken before a meal to aid in digestion. 

General Interaction 

There are no known supplement or food interactions associated with Chlorella 

Possible Side Effects 

Chlorella can cause diarrhea, abdominal cramping, flatus, and nausea – especially during the first week of treatment – and fatigue. 

Some allergic reactions, including asthma and anaphylaxis, have been reported in people taking chlorella and in those preparing chlorella tablets. Rarely, it can also cause infections. 


Chlorella has been found to be safe for short-term treatments, up to two months. 
Chlorella is not recommended during pregnancy or lactation. 

Evidence Based Rating Scale 

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies with what our clinical advisors have found to be efficacious in their personal practice. This tool is meant to simplify which supplements and therapies demonstrate promise in the treatment of certain conditions. This scale does not take into account any possible interactions with any medication/ condition/ or therapy which you may be currently undertaking. It is therefore advisable to ask your doctor before starting any new treatment regimen.








Bad breath










Chlorophyll-rich solutions containing Chlorella have shown efficacy.





















Small clinical trials and anecdotal evidence suggest efficacy in relieving pain and improving quality of life. Larger trials are needed to confirm or refute these initial findings.









Flu vaccine boost











Recent in vitro studies confirm potential to boost antibody response. Older clinical trials indicated no efficacy. New clinical trials are needed to confirm in vitro findings.



Date Published: 06/11/2007

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