Chlorella: Benefits and Side Effects

Due to the high costs associated with growing Chlorella is not as a major food source as originally planned and now exist in its current form in being a supplement or used in medicine.


Chlorella is a genus of algae found in freshwater that contain many health benefits.

It’s harvested and processed by many companies worldwide because of its nutritional value. It’s processed for biofuel and used for nutritional supplements, animal feed, cosmetic products, food ingredients, and more.

Chlorella may be a good source of:

  • protein
  • carotenoids
  • vitamins (B, B12, C)
  • minerals (magnesium, potassium, iron, calcium, etc.)
  • fatty acids (Omega-3)
  • lipids
  • sugars
  • antioxidants

Researchers and some clinical trials have found that Chlorella is capable of treating and preventing some diseases.


Benefits of Chlorella

May increase the quality of breast milk

In a research study wherein mothers took chlorella during their term, their breast milk saw an increase in antibodies called immunoglobulin, type A (IgA). The IgA handles the protection of the body from viruses and from oral respiratory diseases such as colds. The better concentration of breast milk can give a better immune system for babies. A 2017 study also tested ten pregnant women who took Chlorella daily until the day of their delivery and results found that their carotenoid status in their breast milk improved.

May give a better immune system

Research on the relationship between the immune system and the benefits and side effects of Chlorella is limited, with some studies finding little to no relationship with both. But some studies have found promising results.

A Japan study with kendo athletes found that consumption of the microalgae protected them from an increased risk in infection as their IgA (immunoglobulin, type A) levels did not drop compared to athletes who did not take the Chlorella.

In another study, a group of healthy adults took Chlorella for 28 days and at the end of the test found that adults 50 years old and above had an increase in their antibodies.

There was also a test where participants have supplemented Chlorella during days of intense training and results showed their secretory IgA increased during their rest periods.

Chlorella is an alternative supplement for a better immune system but more research is necessary.

May reduce stress

There has been evidence that helps reduce stress is one of the benefits and side effects of Chlorella. One study found that a strain of Chlorella that’s called Chlorella vulgaris reduced the impact of stressors in the brain.

Similar results were also found in another study where male participants had a reduced level of stress after 4 weeks when taking Chlorella compared to those who took a placebo. There are no final results but it seems that the green-celled algae have the potential to aid in stress reduction.

May give better results and rest from exercise

One of the potential benefits and side effects of Chlorella is an increased endurance during exercise though no specific link has been found. An example is that one study found that Chlorella can result in better tolerance of fatigue during rest after 30 minutes of intense exercise. A Japan study wherein participants underwent 4 weeks of high-intensity training while taking Chlorella found that intake of the microalgae gave an increased performance during the exercise and better metabolism afterward.

May be able to help prevent cancer

Several Chlorella strains are able to reduce cancer cells in the human body. A study in Taiwan where the Chlorella was taken orally and another study in China where it was used to treat cells found that Chlorella is capable of destroying lung cancer cells. An experiment also found that it can also prevent the formation of tumors that can cause breast cancer.

May be able to treat depression

Treatment of depression is possible as one of chlorella’s benefits and side effects. A 6-week study found that its extract managed to reduce the symptoms of depression and aided the effects of antidepressant therapy with no adverse side effects.

May reduce the risk of developing diseases for pregnant women

A clinical trial found that one of the benefits and side effects of chlorella is reducing the risk of developing anemia, proteinuria, and edema during pregnancy. Chlorella supplementation may help pregnant women to keep healthy during their term.

May reduce blood pressure

Reducing blood pressure is one of the health benefits and side effects of Chlorella and can be a good supplement for those with diseases such as hypertension.

A College of Virginia study with 33 hypertensive patients found that their high blood pressure saw reduction after taking pure Chlorella and Chlorella extract after a few months and concluded this warranted further studies on this result.

There is also another study where participants took a Chlorella-rich supplement for 12 weeks and the results of the study suggested that the supplement decreased high blood pressure and borderline hypertension and is capable of preventing hypertension.


Side Effects

Though there have been many positive health benefits and side effects of Chlorella as listed above, certain negative side effects have been found in some studies and must be noted before taking it.

A Polish study found that consumers reported suffering from negative side effects such as diarrhea, nausea, and skin rash. Consumers with medical conditions such as hypothyroidism also saw an increase in these side effects.

Those with an allergy to the green-celled algae might also suffer the side effects as reported in the Polish study or in a South Korea study.

Consultation with a medical professional is necessary before taking any Chlorella-based supplement.



Though further studies are necessary, there have been promising initial results with the benefits and side effects of Chlorella. It is safe to consume in most cases and may give improved health.


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