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Chlorella is a type of freshwater seaweed (green algae). It contains protein, iron, vitamins B and C, and other antioxidants.

It may contain substances that fight bacteria, fungi, tumors, and viruses.

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Why do people take chlorella?

Chlorella may help your immune system work better. Some evidence suggests chlorella may:

  • Help people with certain tumors better tolerate chemotherapy and radiation.
  • Raise white blood cell count in people with HIV or cancer, which helps your body fight infections.
  • Protect against cell damage from radiation and toxic metals, such as lead.

Chlorella may also increase the amount of healthy bacteria in your intestines. Healthy bacteria help prevent stomach upset, diarrhea, and other symptoms.

Chlorella has been used to try to treat gastrointestinal disorders, including:

Chlorella has also been used to try to treat or prevent:

Some people also take chlorella to try to:

  • Boost energy levels
  • Detox the body
  • Improve mental function

More research is needed to determine the effectiveness of chlorella to treat these conditions.

Can you get chlorella naturally from foods?

Chlorella is used as a food additive in Japan.

What are the risks of taking chlorella?

Studies suggest that chlorella may be safe when taken by mouth for a short amount of time, up to two months.

Side effects of chlorella include:

Allergic reactions have been reported in some people taking chlorella. These reactions have included severe breathing problems and a life-threatening allergic reaction called anaphylaxis.

There isn't enough research to know if chlorella is safe for women who are pregnant or breastfeeding.

Chlorella may make it harder for warfarin and other blood-thinning drugs to work.

Some chlorella supplements may contain iodine, so people with thyroid conditions may want to avoid taking chlorella.

Always tell your doctor about any supplements you are taking, including natural ones and those bought without a prescription. That way, your doctor can check on any potential side effects or interactions with any medications.

Supplements are not regulated by the FDA.

WebMD Medical Reference

Reviewed by David Kiefer, MD on February 18, 2015

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