Supplement

Docosahexaenoic Acid

DHA is an omega-3 fat from fish and algae that helps build cell membranes in the brain and eyes. In a small study of 22 people, blood flow to the brain went up, though the evidence is limited, and a large pregnancy trial found no clear difference in postpartum depression symptoms. Results for sleep, child behavior and immune cells also showed no clear difference, on very limited evidence.

Sources: PMID 20959577

Updated 8 November 2026
How we grade
8 studies cited

Best evidence: Grade C
Conditions studied: 13
Outcomes: 58
Graded outcomes: 00111

Evidence by condition

Strong
Moderate
Limited
Very limited

13 conditions

Cognitive Improvement

Cognitive Improvement: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People
	Cerebral Blood Flow Small Increase	Improves (the measure goes up)	Small effect		22 people
	Cerebral Oxygenation	Improves (the measure goes up)		1 study	22 people
Studies that measured cerebral oxygenation DHA-rich oil modulates the cerebral haemodynamic response to cognitive tasks in healthy young adults: a near IR spectroscopy pilot studyBr J Nutr · PMID 22018509

Depression

Depression: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Size	Studies	People
	Depression Symptoms No effect	NoneNo effect	1 study	36 people
Studies that measured depression symptoms A double-blind, placebo-controlled study of the omega-3 fatty acid docosahexaenoic acid in the treatment of major depressionAm J Psychiatry · PMID 12727707
	Postpartum Depression Symptoms No effect	NoneNo effect	1 study	2,320 people
Studies that measured postpartum depression symptoms Effect of DHA supplementation during pregnancy on maternal depression and neurodevelopment of young children: a randomized controlled trialJAMA · PMID 20959577

Immune Health

B Cell Count
Inflammation: improves
Natural Killer Cell Activity: improves

Immune Health: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People
	B Cell Count No effect		NoneNo effect	1 study	58 people
Studies that measured b cell count Docosahexaenoic acid ingestion inhibits natural killer cell activity and production of inflammatory mediators in young healthy menLipids · PMID 10443964
	Inflammation	Improves (the measure goes down)			12 people
	Natural Killer Cell Activity	Improves (the measure goes up)			58 people
	Natural Killer Cell Content	Improves (the measure goes up)			46 people
	Oxidative Stress Biomarkers	Improves (the measure goes down)			46 people
	T Cell Count	Improves (the measure goes up)			58 people
	TNF-Alpha	Improves (the measure goes down)			12 people

Metabolic Health

B Cell Count
Pre-Eclampsia Risk
Infant Death Risk: improves

Metabolic Health: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People
	B Cell Count No effect		NoneNo effect	1 study	12 people
Studies that measured b cell count Docosahexaenoic acid ingestion inhibits natural killer cell activity and production of inflammatory mediators in young healthy menLipids · PMID 10443964
	Pre-Eclampsia Risk No effect			1 study	2,399 people
Studies that measured pre-eclampsia risk Fish-oil supplementation in pregnancy does not reduce the risk of gestational diabetes or preeclampsiaAm J Clin Nutr · PMID 22552037
	Infant Death Risk	Improves (the measure goes down)			2,399 people
	Inflammation	Improves (the measure goes down)			12 people
	T Cell Count	Improves (the measure goes up)			12 people
	TNF-Alpha	Improves (the measure goes down)			12 people

Healthy Childhood Development

Child behavioral development

Healthy Childhood Development: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Child behavioral development No effect		NoneNo effect	1 study	132 people
Studies that measured child behavioral development Maternal high-dose docosahexaenoic acid supplementation and neurodevelopment at 5 Years of preterm children.Clin Nutr ESPEN · PMID 39396702

Pregnancy and Delivery Health

Cognition of Offspring
Infant Birth Weight: worsens
Postpartum Depression Symptoms

Pregnancy and Delivery Health: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People
	Cognition of Offspring No effect		NoneNo effect		2,320 people
	Infant Birth Weight Increase	Worsens (the measure goes up)		1 study	5,710 people
Studies that measured infant birth weight Docosahexaenoic Acid and Pregnancy: A Systematic Review and Meta-Analysis of the Association with Improved Maternal and Fetal Health.Nutr Res · PMID 39067112
	Postpartum Depression Symptoms No effect			1 study	2,320 people
Studies that measured postpartum depression symptoms Effect of DHA supplementation during pregnancy on maternal depression and neurodevelopment of young children: a randomized controlled trialJAMA · PMID 20959577

High Blood Pressure

Blood glucose
Insulin: changes; see studies
Blood Pressure: improves

High Blood Pressure: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect		59 people
	Insulin	Changes; see studies		1 study	59 people
Studies that measured insulin Effects of purified eicosapentaenoic and docosahexaenoic acids on glycemic control, blood pressure, and serum lipids in type 2 diabetic patients with treated hypertensionAm J Clin Nutr · PMID 12399272
	Blood Pressure	Improves (the measure goes down)			59 people
	C-Peptide	Improves (the measure goes up)			59 people
	HbA1c	Improves (the measure goes down)			59 people
	Heart Rate	Improves (the measure goes down)			59 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			59 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			59 people
	Total cholesterol	Improves (the measure goes down)			59 people
	Triglycerides	Improves (the measure goes down)			59 people

High Cholesterol

Blood glucose
Insulin: changes; see studies
Blood Pressure: improves

High Cholesterol: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect		59 people
	Insulin	Changes; see studies		1 study	59 people
Studies that measured insulin Effects of purified eicosapentaenoic and docosahexaenoic acids on glycemic control, blood pressure, and serum lipids in type 2 diabetic patients with treated hypertensionAm J Clin Nutr · PMID 12399272
	Blood Pressure	Improves (the measure goes down)			59 people
	C-Peptide	Improves (the measure goes up)			59 people
	HbA1c	Improves (the measure goes down)			59 people
	Heart Rate	Improves (the measure goes down)			59 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			59 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			59 people
	Total cholesterol	Improves (the measure goes down)			59 people
	Triglycerides	Improves (the measure goes down)			59 people

Type 2 Diabetes

Blood glucose
Insulin: changes; see studies
Blood Pressure: improves

Type 2 Diabetes: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect		59 people
	Insulin	Changes; see studies		1 study	59 people
Studies that measured insulin Effects of purified eicosapentaenoic and docosahexaenoic acids on glycemic control, blood pressure, and serum lipids in type 2 diabetic patients with treated hypertensionAm J Clin Nutr · PMID 12399272
	Blood Pressure	Improves (the measure goes down)			59 people
	C-Peptide	Improves (the measure goes up)			59 people
	HbA1c	Improves (the measure goes down)			59 people
	Heart Rate	Improves (the measure goes down)			59 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			59 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			59 people
	Total cholesterol	Improves (the measure goes down)			59 people
	Triglycerides	Improves (the measure goes down)			59 people

General Cardiovascular Health

Infant Death Risk
Pre-Eclampsia Risk

General Cardiovascular Health: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Size	Studies	People
	Infant Death Risk No effect	NoneNo effect		2,399 people
	Pre-Eclampsia Risk No effect		1 study	2,399 people
Studies that measured pre-eclampsia risk Fish-oil supplementation in pregnancy does not reduce the risk of gestational diabetes or preeclampsiaAm J Clin Nutr · PMID 22552037

Sleep Health

Sleep Duration
Wakefulness: improves
Sleep Latency: improves

Sleep Health: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People
	Sleep Duration No effect		NoneNo effect		362 people
	Wakefulness	Improves (the measure goes down)		1 study	362 people
Studies that measured wakefulness Fatty acids and sleep in UK children: subjective and pilot objective sleep results from the DOLAB study--a randomized controlled trialJ Sleep Res · PMID 24605819
	Sleep Latency	Improves (the measure goes down)			362 people

Premature Birth

Child behavioral development

Premature Birth: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Child behavioral development No effect			1 study	132 people
Studies that measured child behavioral development Maternal high-dose docosahexaenoic acid supplementation and neurodevelopment at 5 Years of preterm children.Clin Nutr ESPEN · PMID 39396702

Healthy Childhood Development

Child behavioral development

Healthy Childhood Development: outcomes studied for Docosahexaenoic Acid
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Child behavioral development No effect			1 study	132 people

Key findings

Cerebral Blood FlowCognitive ImprovementImproves (the measure goes up)
Depression SymptomsDepression
Postpartum Depression SymptomsDepression

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Grade C

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Studies cited

8 studies from PubMed

A double-blind, placebo-controlled study of the omega-3 fatty acid docosahexaenoic acid in the treatment of major depressionAm J Psychiatry · PMID 12727707
Effect of DHA supplementation during pregnancy on maternal depression and neurodevelopment of young children: a randomized controlled trialJAMA · PMID 20959577
Docosahexaenoic Acid and Pregnancy: A Systematic Review and Meta-Analysis of the Association with Improved Maternal and Fetal Health.Nutr Res · PMID 39067112
Maternal high-dose docosahexaenoic acid supplementation and neurodevelopment at 5 Years of preterm children.Clin Nutr ESPEN · PMID 39396702
Fatty acids and sleep in UK children: subjective and pilot objective sleep results from the DOLAB study--a randomized controlled trialJ Sleep Res · PMID 24605819
Effects of purified eicosapentaenoic and docosahexaenoic acids on glycemic control, blood pressure, and serum lipids in type 2 diabetic patients with treated hypertensionAm J Clin Nutr · PMID 12399272
Docosahexaenoic acid ingestion inhibits natural killer cell activity and production of inflammatory mediators in young healthy menLipids · PMID 10443964
Fish-oil supplementation in pregnancy does not reduce the risk of gestational diabetes or preeclampsiaAm J Clin Nutr · PMID 22552037

Evidence by condition

General Cardiovascular Health

Healthy Childhood Development

Key findings

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Studies cited

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