Chlorella

Studies in people

• Benefit

  Iron levels in the blood³

  In people and animals, chlorella raised iron levels and helped red blood cells, but longer human studies are needed.

• Open question

  Heart health⁴

  Chlorella may help lower inflammation and oxidative stress, but studies on heart risk factors show mixed results.

• Benefit

  Heart and blood vessel health⁵

  In people with mildly high cholesterol, daily chlorella supplements lowered blood triglycerides and total cholesterol.

• No harm found

  Blood pressure and cholesterol⁶

  In people, chlorella supplements did not change blood pressure or cholesterol levels.

• Benefit

  Heart and blood sugar health⁷

  Chlorella may improve cholesterol, blood pressure and blood sugar, but scientists do not yet know which compounds in it do this.

• Benefit

  Heart and blood health⁸

  In people, taking chlorella lowered cholesterol, blood pressure and blood sugar, but not triglycerides, good cholesterol or weight.

• Benefit

  Blood sugar and cholesterol⁹

  In people, chlorella supplements have been suggested to help lower blood sugar and cholesterol.

• Benefit

  Menstrual pain relief¹¹

  In women with period pain, taking chlorella reduced how bad and how long the pain lasted.

• Benefit

  Clearing cooking chemicals¹²

  In people, chlorella may help clear some harmful cooking chemicals from the body, but scientists do not yet know for sure.

• No harm found

  Food allergy potential¹³

  Chlorella did not cause allergic skin reactions in people, and animal studies found no DNA damage.

• Benefit

  Blood pressure control¹⁴

  In people with slightly high blood pressure, GABA-rich chlorella taken twice daily for 12 weeks lowered systolic blood pressure.

• Open question

  DNA damage in smokers¹⁵

  In smokers, chlorella raised blood antioxidants, but DNA damage dropped with placebo too, so the benefit is unclear.

• Open question

  Immune response to flu shot¹⁶

  Chlorella did not raise flu-shot antibodies overall, though people 50 to 55 saw a rise.

• Open question

  Exercise recovery after cycling¹⁷

  In people, taking chlorella for two days lowered blood lactate after cycling but did not boost peak fitness.

Animal and lab studies only

• Benefit

  Skin aging and repair²²

  In lab and animal studies, chlorella fractions may support cell repair under stress, but human evidence is lacking.

• Benefit

  Gut bacteria balance²³

  In lab studies, chlorella helped gut bacteria make more good acids and crowd out harmful ones.

• Benefit

  Skin allergy symptoms²⁴

  In mice, chlorella lessened atopic dermatitis-like skin symptoms, but whether it helps people is not yet known.

Study type not stated

• Benefit

  Blood pressure and gut health²⁰

  Chlorella may help blood pressure and gut bacteria, but scientists do not yet know for sure.

• Benefit

  Nutritional and health benefits²¹

  Chlorella is packed with vitamins, proteins and fats, and studies suggest it may help fight disease.

Found in some samples or products

These come from where it was grown, how it was processed or cooked, or what it was made into. They are not about the ingredient itself, so the signal does not count them.

• Contaminants in microalgae food¹⁸

  Chlorella grown in different ways may carry germs and toxins that current food rules don't check for.

• Heavy metals in food¹⁹

  Chlorella can pick up heavy metals from where it grows, so quality checks matter.

Single cases of misuse or overdose

One person or one incident, such as an accidental overdose or a mistake in a kitchen or factory. They are real, but a single case does not show what happens at normal amounts, so the signal does not count them.

• Sun-triggered skin reaction¹⁰

  Five people who ate chlorella tablets got swollen, purple skin sores on sun-exposed areas.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least one finding in people. When most findings in people point one way, the page leans that way (“Mostly”), and every finding is still shown. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.