Supplement

Chlorella

Chlorella is a single-celled freshwater green alga, rich in protein, chlorophyll, iron and B vitamins, that people eat as a nutrient-dense food supplement. Most people look at it for iron deficiency anemia, and the evidence is limited: one small trial in pregnant women found their risk of anemia improved. Because that finding comes from a single study of 70 people, it is too early to say how well it applies to others.

Sources: PMID 20013055

Updated 30 September 2026
How we grade
9 studies cited

Best evidence: Grade B
Conditions studied: 11
Outcomes: 51
Graded outcomes: 0136

Evidence by condition

Strong
Moderate
Limited
Very limited

11 conditions

High Blood Pressure

High Blood Pressure: outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People
	Blood Pressure Small Improvement	Improves (the measure goes down)	Small effect	3 studies	797 people
Studies that measured blood pressure Effect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trialsClin Nutr · PMID 29037431 Anti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens · PMID 19811362 Quantifying the Impact of Algae Supplement on Blood Pressure: Systematic Review and Meta-analysis of Randomized Controlled Trials.Curr Probl Cardiol · PMID 35870546
	Blood glucose No effect		NoneNo effect	1 study	797 people
Studies that measured blood glucose Quantifying the Effect of Supplementation with Algae and Its Extracts on Glycolipid Metabolism: A Meta-Analysis of Randomized Controlled Trials.Nutrients · PMID 32521609
	Body Mass Index (BMI)	Improves (the measure goes down)			797 people
	Heart Rate	Improves (the measure goes down)			77 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			797 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			797 people
	Total cholesterol	Improves (the measure goes down)			797 people
	Triglycerides	Improves (the measure goes down)			797 people
	Weight	Improves (the measure goes down)			77 people

Pregnancy and Delivery Health

Pregnancy and Delivery Health: outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People
	Anemia Risk Small Improvement	Improves (the measure goes down)	Small effect	1 study	70 people
Studies that measured anemia risk Chlorella pyrenoidosa supplementation reduces the risk of anemia, proteinuria and edema in pregnant womenPlant Foods Hum Nutr · PMID 20013055
	Blood Pressure	Improves (the measure goes down)		3 studies	736 people
Studies that measured blood pressure Effect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trialsClin Nutr · PMID 29037431 Anti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens · PMID 19811362 Quantifying the Impact of Algae Supplement on Blood Pressure: Systematic Review and Meta-analysis of Randomized Controlled Trials.Curr Probl Cardiol · PMID 35870546
	Leg Edema	Changes; see studies			70 people
	Proteinuria	Improves (the measure goes up)			70 people

Iron Deficiency Anemia

Anemia Risk: improves
Blood Pressure: improves
Leg Edema: changes; see studies

Iron Deficiency Anemia: outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People
	Anemia Risk Small Improvement	Improves (the measure goes down)	Small effect	1 study	70 people
Studies that measured anemia risk Chlorella pyrenoidosa supplementation reduces the risk of anemia, proteinuria and edema in pregnant womenPlant Foods Hum Nutr · PMID 20013055
	Blood Pressure	Improves (the measure goes down)		3 studies	70 people
Studies that measured blood pressure Effect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trialsClin Nutr · PMID 29037431 Anti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens · PMID 19811362 Quantifying the Impact of Algae Supplement on Blood Pressure: Systematic Review and Meta-analysis of Randomized Controlled Trials.Curr Probl Cardiol · PMID 35870546
	Leg Edema	Changes; see studies			70 people
	Proteinuria	Improves (the measure goes up)			70 people

Metabolic Health

Anti-Oxidant Enzyme Profile: improves
Blood Pressure: improves
DNA Damage: changes; see studies

Metabolic Health: outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People
	Anti-Oxidant Enzyme Profile Small Increase	Improves (the measure goes up)	Small effect	1 study	52 people
Studies that measured anti-oxidant enzyme profile Six-week supplementation with Chlorella has favorable impact on antioxidant status in Korean male smokersNutrition · PMID 19660910
	Blood Pressure	Improves (the measure goes down)		3 studies	52 people
Studies that measured blood pressure Effect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trialsClin Nutr · PMID 29037431 Anti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens · PMID 19811362 Quantifying the Impact of Algae Supplement on Blood Pressure: Systematic Review and Meta-analysis of Randomized Controlled Trials.Curr Probl Cardiol · PMID 35870546
	DNA Damage	Changes; see studies			52 people

High Cholesterol

Blood glucose
Blood Pressure: improves
Body Mass Index (BMI): improves

High Cholesterol: outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect	1 study	255 people
Studies that measured blood glucose Quantifying the Effect of Supplementation with Algae and Its Extracts on Glycolipid Metabolism: A Meta-Analysis of Randomized Controlled Trials.Nutrients · PMID 32521609
	Blood Pressure	Improves (the measure goes down)		3 studies	797 people
Studies that measured blood pressure Effect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trialsClin Nutr · PMID 29037431 Anti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens · PMID 19811362 Quantifying the Impact of Algae Supplement on Blood Pressure: Systematic Review and Meta-analysis of Randomized Controlled Trials.Curr Probl Cardiol · PMID 35870546
	Body Mass Index (BMI)	Improves (the measure goes down)			797 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			797 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			797 people
	Total cholesterol	Improves (the measure goes down)			797 people
	Triglycerides	Improves (the measure goes down)			797 people

Nonalcoholic Fatty Liver Disease (NAFLD)

Blood glucose
Blood Pressure: improves
Body Mass Index (BMI): improves

Nonalcoholic Fatty Liver Disease (NAFLD): outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect	1 study	255 people
Studies that measured blood glucose Quantifying the Effect of Supplementation with Algae and Its Extracts on Glycolipid Metabolism: A Meta-Analysis of Randomized Controlled Trials.Nutrients · PMID 32521609
	Blood Pressure	Improves (the measure goes down)		3 studies	797 people
Studies that measured blood pressure Effect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trialsClin Nutr · PMID 29037431 Anti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens · PMID 19811362 Quantifying the Impact of Algae Supplement on Blood Pressure: Systematic Review and Meta-analysis of Randomized Controlled Trials.Curr Probl Cardiol · PMID 35870546
	Body Mass Index (BMI)	Improves (the measure goes down)			797 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			797 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			797 people
	Total cholesterol	Improves (the measure goes down)			797 people
	Triglycerides	Improves (the measure goes down)			797 people

Dyslipidemia

Blood glucose
Blood Pressure: improves
Body Mass Index (BMI): improves

Dyslipidemia: outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect	1 study	255 people
Studies that measured blood glucose Quantifying the Effect of Supplementation with Algae and Its Extracts on Glycolipid Metabolism: A Meta-Analysis of Randomized Controlled Trials.Nutrients · PMID 32521609
	Blood Pressure	Improves (the measure goes down)		3 studies	797 people
Studies that measured blood pressure Effect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trialsClin Nutr · PMID 29037431 Anti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens · PMID 19811362 Quantifying the Impact of Algae Supplement on Blood Pressure: Systematic Review and Meta-analysis of Randomized Controlled Trials.Curr Probl Cardiol · PMID 35870546
	Body Mass Index (BMI)	Improves (the measure goes down)			797 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			797 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			797 people
	Total cholesterol	Improves (the measure goes down)			797 people
	Triglycerides	Improves (the measure goes down)			797 people

Obesity

Blood glucose
High-density lipoprotein (HDL): improves
Low-density lipoprotein (LDL): improves

Obesity: outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect	1 study	255 people
Studies that measured blood glucose Quantifying the Effect of Supplementation with Algae and Its Extracts on Glycolipid Metabolism: A Meta-Analysis of Randomized Controlled Trials.Nutrients · PMID 32521609
	High-density lipoprotein (HDL)	Improves (the measure goes up)			255 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			255 people
	Total cholesterol	Improves (the measure goes down)			255 people
	Triglycerides	Improves (the measure goes down)			255 people

Immune Health

Body Fat
Immunity: improves
Vaccine Augmentation: improves

Immune Health: outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People
	Body Fat No effect		NoneNo effect		15 people
	Immunity	Improves (the measure goes up)		1 study	15 people
Studies that measured immunity Salivary secretory immunoglobulin A secretion increases after 4-weeks ingestion of chlorella-derived multicomponent supplement in humans: a randomized cross over studyNutr J · PMID 21906314
	Vaccine Augmentation	Improves (the measure goes up)		1 study	117 people
Studies that measured vaccine augmentation Safety and immunoenhancing effect of a Chlorella-derived dietary supplement in healthy adults undergoing influenza vaccination: randomized, double-blind, placebo-controlled trialCMAJ · PMID 12874157

Type 2 Diabetes

Blood Pressure: improves

Type 2 Diabetes: outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Blood Pressure	Improves (the measure goes down)		3 studies	666 people
Studies that measured blood pressure Effect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trialsClin Nutr · PMID 29037431 Anti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens · PMID 19811362 Quantifying the Impact of Algae Supplement on Blood Pressure: Systematic Review and Meta-analysis of Randomized Controlled Trials.Curr Probl Cardiol · PMID 35870546

Fibromyalgia

Fibromyalgia Symptoms: improves

Fibromyalgia: outcomes studied for Chlorella
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Fibromyalgia Symptoms	Improves (the measure goes down)		1 study	18 people
Studies that measured fibromyalgia symptoms Nutritional supplementation with Chlorella pyrenoidosa for patients with fibromyalgia syndrome: a pilot studyPhytother Res · PMID 10815009

Key findings

Blood PressureHigh Blood PressureImproves (the measure goes down)
Anemia RiskPregnancy and Delivery HealthImproves (the measure goes down)
Anti-Oxidant Enzyme ProfileMetabolic HealthImproves (the measure goes up)

Shop the evidence-backed picks

Third-party tested Chlorella products, in the forms the graded studies used where we can match them.

Grade B

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Studies cited

9 studies from PubMed

Safety and immunoenhancing effect of a Chlorella-derived dietary supplement in healthy adults undergoing influenza vaccination: randomized, double-blind, placebo-controlled trialCMAJ · PMID 12874157
Salivary secretory immunoglobulin A secretion increases after 4-weeks ingestion of chlorella-derived multicomponent supplement in humans: a randomized cross over studyNutr J · PMID 21906314
Effect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trialsClin Nutr · PMID 29037431
Anti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens · PMID 19811362
Quantifying the Impact of Algae Supplement on Blood Pressure: Systematic Review and Meta-analysis of Randomized Controlled Trials.Curr Probl Cardiol · PMID 35870546
Six-week supplementation with Chlorella has favorable impact on antioxidant status in Korean male smokersNutrition · PMID 19660910
Chlorella pyrenoidosa supplementation reduces the risk of anemia, proteinuria and edema in pregnant womenPlant Foods Hum Nutr · PMID 20013055
Nutritional supplementation with Chlorella pyrenoidosa for patients with fibromyalgia syndrome: a pilot studyPhytother Res · PMID 10815009
Quantifying the Effect of Supplementation with Algae and Its Extracts on Glycolipid Metabolism: A Meta-Analysis of Randomized Controlled Trials.Nutrients · PMID 32521609

Evidence by condition

Key findings

Shop the evidence-backed picks

Studies cited

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