Supplement

Krill Oil

Krill oil is an oil from small Antarctic crustaceans that supplies the omega-3 fats EPA and DHA, which help build cell membranes and shape how the body manages inflammation. People most often look at it for rheumatoid arthritis, and a trial of 90 people found arthritis symptoms improved, though the evidence is limited. That finding comes from a single moderate-sized study, so it needs more trials to confirm it, and the other results so far, such as lower CRP in knee osteoarthritis, are similarly limited.

Sources: PMID 17353582

Updated 30 September 2026
How we grade
6 studies cited

Best evidence: Grade C
Conditions studied: 10
Outcomes: 46
Graded outcomes: 00110

Evidence by condition

Strong
Moderate
Limited
Very limited

10 conditions

Osteoarthritis (OA)

Osteoarthritis (OA): outcomes studied for Krill Oil
Grade	Outcome	Effect	Size	Studies	People
	C-Reactive Protein (CRP) Moderate Decrease	Improves (the measure goes down)	Moderate effect	2 studies	352 people
Studies that measured c-reactive protein (crp) Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteersLipids · PMID 21042875 Krill Oil for Knee Osteoarthritis: A Randomized Clinical Trial.JAMA · PMID 38776073
	Arthritis (In General) Moderate Improvement	Improves (the measure goes up)	Moderate effect	1 study	90 people
Studies that measured arthritis (in general) Evaluation of the effect of Neptune Krill Oil on chronic inflammation and arthritic symptomsJ Am Coll Nutr · PMID 17353582
	Functionality in Elderly or Injured	Improves (the measure goes up)			90 people
	Pain	Improves (the measure goes down)			262 people
	Quality of Life	Improves (the measure goes up)			262 people

Cardiovascular Disease

Cardiovascular Disease: outcomes studied for Krill Oil
Grade	Outcome	Effect	Size	Studies	People
	C-Reactive Protein (CRP) Moderate Decrease	Improves (the measure goes down)	Moderate effect	2 studies	90 people
Studies that measured c-reactive protein (crp) Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteersLipids · PMID 21042875 Krill Oil for Knee Osteoarthritis: A Randomized Clinical Trial.JAMA · PMID 38776073
	Functionality in Elderly or Injured	Improves (the measure goes up)			90 people

Primary Dysmenorrhea (Menstrual Cramps)

Breast Tenderness: improves
Irritability: improves
PMS Symptoms: improves

Primary Dysmenorrhea (Menstrual Cramps): outcomes studied for Krill Oil
Grade	Outcome	Effect	Size	Studies	People
	Breast Tenderness Small Improvement	Improves (the measure goes down)	Small effect	1 study	70 people
Studies that measured breast tenderness Evaluation of the effects of Neptune Krill Oil on the management of premenstrual syndrome and dysmenorrheaAltern Med Rev · PMID 12777162
	Irritability	Improves (the measure goes down)			70 people
	PMS Symptoms	Improves (the measure goes down)			70 people
	Stress Signs and Symptoms	Improves (the measure goes down)			70 people

Obesity

2-Arachidonoylglycerol Acid: improves
Blood glucose: improves
Insulin: changes; see studies

Obesity: outcomes studied for Krill Oil
Grade	Outcome	Effect	Size	Studies	People
	2-Arachidonoylglycerol Acid Small Decrease	Improves (the measure goes down)	Small effect	1 study	63 people
Studies that measured 2-arachidonoylglycerol acid Krill oil significantly decreases 2-arachidonoylglycerol plasma levels in obese subjectsNutr Metab · PMID 21276269
	Blood glucose	Improves (the measure goes down)			63 people
	Insulin	Changes; see studies			63 people
	Weight	Improves (the measure goes down)			63 people

Premenstrual Syndrome (PMS)

Breast Tenderness: improves
Irritability: improves
PMS Symptoms: improves

Premenstrual Syndrome (PMS): outcomes studied for Krill Oil
Grade	Outcome	Effect	Size	Studies	People
	Breast Tenderness Small Improvement	Improves (the measure goes down)	Small effect	1 study	70 people
Studies that measured breast tenderness Evaluation of the effects of Neptune Krill Oil on the management of premenstrual syndrome and dysmenorrheaAltern Med Rev · PMID 12777162
	Irritability	Improves (the measure goes down)			70 people
	PMS Symptoms	Improves (the measure goes down)			70 people
	Stress Signs and Symptoms	Improves (the measure goes down)			70 people

Rheumatoid Arthritis (RA)

Arthritis (In General): improves
C-Reactive Protein (CRP): improves
Functionality in Elderly or Injured: improves

Rheumatoid Arthritis (RA): outcomes studied for Krill Oil
Grade	Outcome	Effect	Size	Studies	People
	Arthritis (In General) Moderate Improvement	Improves (the measure goes up)	Moderate effect	1 study	90 people
Studies that measured arthritis (in general) Evaluation of the effect of Neptune Krill Oil on chronic inflammation and arthritic symptomsJ Am Coll Nutr · PMID 17353582
	C-Reactive Protein (CRP)	Improves (the measure goes down)		2 studies	90 people
Studies that measured c-reactive protein (crp) Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteersLipids · PMID 21042875 Krill Oil for Knee Osteoarthritis: A Randomized Clinical Trial.JAMA · PMID 38776073
	Functionality in Elderly or Injured	Improves (the measure goes up)			90 people

Overweight

2-Arachidonoylglycerol Acid: improves
Blood glucose: improves
Insulin: changes; see studies

Overweight: outcomes studied for Krill Oil
Grade	Outcome	Effect	Size	Studies	People
	2-Arachidonoylglycerol Acid Small Decrease	Improves (the measure goes down)	Small effect	1 study	63 people
Studies that measured 2-arachidonoylglycerol acid Krill oil significantly decreases 2-arachidonoylglycerol plasma levels in obese subjectsNutr Metab · PMID 21276269
	Blood glucose	Improves (the measure goes down)			63 people
	Insulin	Changes; see studies			63 people
	Weight	Improves (the measure goes down)			63 people

High Cholesterol

High-density lipoprotein (HDL): improves
Total cholesterol: improves
Low-density lipoprotein (LDL): improves

High Cholesterol: outcomes studied for Krill Oil
Grade	Outcome	Effect	Size	Studies	People
	High-density lipoprotein (HDL) Moderate Improvement	Improves (the measure goes up)	Moderate effect		120 people
	Total cholesterol	Improves (the measure goes down)		1 study	120 people
Studies that measured total cholesterol Evaluation of the effects of Neptune Krill Oil on the clinical course of hyperlipidemiaAltern Med Rev · PMID 15656713
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			120 people
	Triglycerides	Improves (the measure goes down)			120 people

General Cardiovascular Health

Apolipoprotein A: improves
C-Reactive Protein (CRP): improves
Total cholesterol: improves

General Cardiovascular Health: outcomes studied for Krill Oil
Grade	Outcome	Effect	Size	Studies	People
	Apolipoprotein A Small Decrease	Improves (the measure goes down)	Small effect		115 people
	C-Reactive Protein (CRP)	Improves (the measure goes down)		2 studies	115 people
Studies that measured c-reactive protein (crp) Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteersLipids · PMID 21042875 Krill Oil for Knee Osteoarthritis: A Randomized Clinical Trial.JAMA · PMID 38776073
	Total cholesterol	Improves (the measure goes down)		1 study	115 people
Studies that measured total cholesterol Evaluation of the effects of Neptune Krill Oil on the clinical course of hyperlipidemiaAltern Med Rev · PMID 15656713
	Apolipoprotein B	Improves (the measure goes down)			115 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			115 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			115 people
	Oxidative Stress Biomarkers	Improves (the measure goes down)			115 people
	Triglycerides	Improves (the measure goes down)			115 people

Metabolic Health

Apolipoprotein A: improves
C-Reactive Protein (CRP): improves
Total cholesterol: improves

Metabolic Health: outcomes studied for Krill Oil
Grade	Outcome	Effect	Size	Studies	People
	Apolipoprotein A Small Decrease	Improves (the measure goes down)	Small effect		115 people
	C-Reactive Protein (CRP)	Improves (the measure goes down)		2 studies	115 people
Studies that measured c-reactive protein (crp) Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteersLipids · PMID 21042875 Krill Oil for Knee Osteoarthritis: A Randomized Clinical Trial.JAMA · PMID 38776073
	Total cholesterol	Improves (the measure goes down)		1 study	115 people
Studies that measured total cholesterol Evaluation of the effects of Neptune Krill Oil on the clinical course of hyperlipidemiaAltern Med Rev · PMID 15656713
	Apolipoprotein B	Improves (the measure goes down)			115 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			115 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			115 people
	Oxidative Stress Biomarkers	Improves (the measure goes down)			115 people
	Triglycerides	Improves (the measure goes down)			115 people

Key findings

C-Reactive Protein (CRP)Osteoarthritis (OA)Improves (the measure goes down)
Arthritis (In General)Osteoarthritis (OA)Improves (the measure goes up)
Breast TendernessPrimary Dysmenorrhea (Menstrual Cramps)Improves (the measure goes down)

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Third-party tested Krill Oil products. The evidence above is limited, so read it before you buy.

Grade C

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Studies cited

6 studies from PubMed

Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteersLipids · PMID 21042875
Evaluation of the effects of Neptune Krill Oil on the clinical course of hyperlipidemiaAltern Med Rev · PMID 15656713
Evaluation of the effect of Neptune Krill Oil on chronic inflammation and arthritic symptomsJ Am Coll Nutr · PMID 17353582
Krill Oil for Knee Osteoarthritis: A Randomized Clinical Trial.JAMA · PMID 38776073
Krill oil significantly decreases 2-arachidonoylglycerol plasma levels in obese subjectsNutr Metab · PMID 21276269
Evaluation of the effects of Neptune Krill Oil on the management of premenstrual syndrome and dysmenorrheaAltern Med Rev · PMID 12777162

Evidence by condition

General Cardiovascular Health

Key findings

Shop Krill Oil

Studies cited

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