Fish oil is a nutrient found in many types of fish. It is high in omega-3-fatty-acids and fat that the body needs for heart health. Fish oil has been used to improve organ function, lower fat levels in the blood, and lower body fat levels. Fish oil can be taken as a pill or oil.
3 to 5 grams daily
What Research Shows
- Attention Deficit and Hyperactivity Disorder (ADHD) —likely to improve symptoms and cognitive function D1
- Chronic kidney disease —likely to lower the risk of end-stage renal disease E1
- Dry eye —likely to ease symptoms M1, M2
- Early and preterm delivery —likely to prevent O1
- Hyperlipidemia —likely to lower triglycerides levels S1
- Insulin sensitivity —likely to increase sensitivity U1
- Liver failure — likely to lower triglycerides and raise HDL (“good”) cholesterol levels W1
- Migraine —likely to reduce migraine duration X1
- Non-alcoholic fatty liver disease —likely to decrease liver fat Y1, Y2
- Psoriasis —likely to ease symptoms BB1, BB2
May Be Effective
- Amyotrophic lateral sclerosis —may help prevent or delay onset B1
- Depression —may ease symptoms in older adults J1-J7
- Heart disease —may lower cholesterol, blood pressure, and heart rate Q1-Q3
- Heart failure —may provide benefit R1
- Infant support —may improve psychomotor and visual development T1, T2
- Pregnancy support —may reduce preterm birth and low birth weight, but may increase risk of large for gestational weight AA1-AA5
- Rheumatoid arthritis —may improve symptoms DD1, DD2
May Not Be Effective
- Age-related macular degeneration —may not provide benefit A1
Unlikely to Be Effective
Not Enough Data to Assess
Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.
It is likely safe to take fish oil in small doses for a short time, but diarrhea and digestive upset are possible. Not enough studies have been done to say whether it is safe to take for a long period.EE1
Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.
A. Age-Related Macular Degeneration
A1. Lawrenson JG, Evans JR. Omega 3 fatty acids for preventing or slowing the progression of age-related macular degeneration. Cochrane Database Syst Rev. 2015 Apr 9;(4):CD010015.
B. Amyotrophic Lateral Sclerosis
B1. Fitzgerald KC, O'Reilly ÉJ, et al. Dietary ω-3 polyunsaturated fatty acid intake and risk for amyotrophic lateral sclerosis. JAMA Neurol. 2014 Sep;71(9):1102-1110.
C1. Woods RK, Thien FC, et al. Dietary marine fatty acids (fish oil) for asthma in adults and children. Cochrane Database Syst Rev. 2002;(3):CD001283.
D. Attention Deficit Hyperactivity Disorder
D1. Chang JP, Su KP, et al. Omega-3 Polyunsaturated Fatty Acids in Youths with Attention Deficit Hyperactivity Disorder: a Systematic Review and Meta-Analysis of Clinical Trials and Biological Studies. Neuropsychopharmacology. 2018 Feb;43(3):534-545.
E. Chronic Kidney Disease
E1. Hu J, Liu Z, et al. Omega-3 fatty acid supplementation as an adjunctive therapy in the treatment of chronic kidney disease: a meta-analysis. Clinics (Sao Paulo). 2017 Jan 1;72(1):58-64.
F. Cognitive Decline
F1. Butler M, Nelson VA, et al. Over-the-Counter Supplement Interventions to Prevent Cognitive Decline, Mild Cognitive Impairment, and Clinical Alzheimer-Type Dementia: A Systematic Review. Ann Intern Med. 2018 Jan 2;168(1):52-62.
G. Crohn Disease
G1. Turner D, Zlotkin SH, et al. Omega 3 fatty acids (fish oil) for maintenance of remission in Crohn’s disease. Cochrane Database Syst Rev. 2007;(2):CD006320.
H. Cystic Fibrosis
H1. Oliver C, Watson H. Omega-3 fatty acids for cystic fibrosis. Cochrane Database Syst Rev. 2016 Jan 5;(1):CD002201.
I1. Burckhardt M, Herke M, et al. Omega-3 fatty acids for the treatment of dementia. Cochrane Database Syst Rev. 2016 Apr 11;4:CD009002.
I2. Canhada S, Castro K, et al. Omega-3 fatty acids' supplementation in Alzheimer's disease: A systematic review. Nutr Neurosci. 2018 Oct;21(8):529-538.
J1. Appleton KM, Sallis HM, et al. Omega-3 fatty acids for depression in adults. Cochrane Database Syst Rev. 2015 Nov 5;(11):CD004692.
J2. Appleton KM, Sallis HM, et al. ω-3 Fatty acids for major depressive disorder in adults: an abridged Cochrane review. BMJ Open. 2016 Mar 2;6(3):e010172.
J3. Mocking RJ, Harmsen I, et al. Meta-analysis and meta-regression of omega-3 polyunsaturated fatty acid supplementation for major depressive disorder. Transl Psychiatry. 2016 Mar 15;6:e756.
J4. Sarris J, Murphy J, et al. Adjunctive Nutraceuticals for Depression: A Systematic Review and Meta-Analyses. Am J Psychiatry. 2016 Jun 1;173(6):575-587.
J5. Schefft C, Kilarski LL, et al. Efficacy of adding nutritional supplements in unipolar depression: A systematic review and meta-analysis. Eur Neuropsychopharmacol. 2017 Nov;27(11):1090-1109.
J6. Bae JH, Kim G. Systematic review and meta-analysis of omega-3-fatty acids in elderly patients with depression. Nutr Res. 2018 Feb;50:1-9.
J7. Bai ZG, Bo A, et al. Omega-3 polyunsaturated fatty acids and reduction of depressive symptoms in older adults: A systematic review and meta-analysis. J Affect Disord. 2018 Dec 1;241:241-248.
K1. Chen C, Yu X, et al. Effects of Omega-3 Fatty Acid Supplementation on Glucose Control and Lipid Levels in Type 2 Diabetes: A Meta-Analysis. PLoS One. 2015 Oct 2;10(10):e0139565.
L. Drug-Resistant Epilepsy
L1. Sarmento Vasconcelos V, Macedo CR, et al. Polyunsaturated fatty acid supplementation for drug-resistant epilepsy. Cochrane Database Syst Rev. 2016 Aug 17;(8):CD011014.
M. Dry Eye
M1. Molina-Leyva I, Molina-Leyva A, et al. Efficacy of nutritional supplementation with omega-3 and omega-6 fatty acids in dry eye syndrome: a systematic review of randomized clinical trials. Acta Ophthalmol. 2017 Dec;95(8):e677-e685.
M2. Giannaccare G, Pellegrini M, et al. Efficacy of Omega-3 Fatty Acid Supplementation for Treatment of Dry Eye Disease: A Meta-Analysis of Randomized Clinical Trials. Cornea. 2019 May;38(5):565-573.
N1. Pattanittum P, Kunyanone N, et al. Dietary supplements for dysmenorrhoea. Cochrane Database Syst Rev. 2016 Mar 22;3:CD002124.
O. Early and Pre-term Delivery
O1. Kar S, Wong M, et al. Effects of omega-3 fatty acids in prevention of early preterm delivery: a systematic review and meta-analysis of randomized studies. Eur J Obstet Gynecol Reprod Biol. 2016 Mar;198:40-46.
P. Heart Attack
P1. Burr ML, Fehily AM, et al. Effects of changes in fat, fish, and fibre intakes on death and myocardial infraction: diet and reinfarction trial (DART). Lancet. 1989;2(8666):757-761.
Q. Heart Disease
Q1. Alexander DD, Miller PE, et al. A Meta-Analysis of Randomized Controlled Trials and Prospective Cohort Studies of Eicosapentaenoic and Docosahexaenoic Long-Chain Omega-3 Fatty Acids and Coronary Heart Disease Risk. Mayo Clin Proc. 2017 Jan;92(1):15-29.
Q2. AbuMweis S, Jew S, et al. Eicosapentaenoic acid and docosahexaenoic acid containing supplements modulate risk factors for cardiovascular disease: a meta-analysis of randomised placebo-control human clinical trials. J Hum Nutr Diet. 2018 Feb;31(1):67-84.
Q3. Abdelhamid AS, Brown TJ, et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2018 Nov 30;11:CD003177.
R. Heart Failure
R1. Wang C, Xiong B, et al. The Role of Omega-3 Polyunsaturated Fatty Acids in Heart Failure: A Meta-Analysis of Randomised Controlled Trials. Nutrients. 2016 Dec 30;9(1). pii: E18.
S1. Eslick GD, Howe PR, et al. Benefits of fish oil supplementation on hyperlipidemia: a systematic review and meta-analysis. Int J Cardiol. 2009;136(1):4-16.
T. Infant Support
T1. Jasani B, Simmer K, et al. Long chain polyunsaturated fatty acid supplementation in infants born at term. Cochrane Database Syst Rev. 2017 Mar 10;3:CD000376.
T2. Shulkin M, Pimpin L, et al. n-3 Fatty Acid Supplementation in Mothers, Preterm Infants, and Term Infants and Childhood Psychomotor and Visual Development: A Systematic Review and Meta-Analysis. J Nutr. 2018 Mar 1;148(3):409-418.
U. Insulin Sensitivity
U1. Gao H, Geng T, et al. Fish oil supplementation and insulin sensitivity: a systematic review and meta-analysis. Lipids Health Dis. 2017 Jul 3;16(1):131.
V. Kidney Failure
V1. Lim AK, Manley KJ, et al. Fish oil for kidney transplant recipients. Cochrane Database Syst Rev. 2016;(8):CD005282.
W. Liver Failure
W1. Zhu W, Dong C, et al. Effects of fish oil on serum lipid profile in dialysis patients: a systematic review and meta-analysis of randomized controlled trials. Lipids Health Dis. 2014;13:127.
X1. Maghsoumi-Norouzabad L, Mansoori A, et al. Effects of omega-3 fatty acids on the frequency, severity, and duration of migraine attacks: A systematic review and meta-analysis of randomized controlled trials. Nutr Neurosci. 2018 Nov;21(9):614-623.
Y. Non-Alcoholic Fatty Liver Disease
Y1. He XX, Wu XL, et al. Effectiveness of Omega-3 Polyunsaturated Fatty Acids in Non-Alcoholic Fatty Liver Disease: A Meta-Analysis of Randomized Controlled Trials. PLoS One. 2016 Oct 6;11(10):e0162368.
Y2. Yan JH, Guan BJ, et al. Omega-3 polyunsaturated fatty acid supplementation and non-alcoholic fatty liver disease: A meta-analysis of randomized controlled trials. Medicine (Baltimore). 2018 Sep;97(37):e12271.
Z1. Bender N, Portmann M, et al. Fish or n3-PUFA intake and body composition: a systematic review and meta-analysis. Obes Rev. 2014 Aug;15(8):657-665.
Z2. Du S, Jin J, et al. Does Fish Oil Have and Anti-Obesity Effect in Overweight/Obese Adults? A Meta-Analysis of Randomized Controlled Trials. PLoS One. 2015;10(11):e0142652.
Z3. Zhang YY, Liu W, et al. Efficacy of Omega-3 Polyunsaturated Fatty Acids Supplementation in Managing Overweight and Obesity: A Meta-Analysis of Randomized Clinical Trials. J Nutr Health Aging. 2017;21(2):187-192.
AA. Pregnancy Support
AA1. Gunaratne AW, Makrides M, et al. Maternal prenatal and/or postnatal n-3 long chain polyunsaturated fatty acids (LCPUFA) supplementation for preventing allergies in early childhood. Cochrane Database Syst Rev. 2015 Jul 22;(7):CD010085.
AA2. Chen B, Ji X, et al. Fish oil supplementation improves pregnancy outcomes and size of the newborn: a meta-analysis of 21 randomized controlled trials. J Matern Fetal Neonatal Med. 2016;29(12):2017-2027.
AA3. Saccone G, Saccone I, et al. Omega-3-long-chain polyunsaturated fatty acids and fish oil supplementation during pregnancy: which evidence? J Matern Fetal Neonatal Med. 2016;29(15):2389-2397.
AA4. Freedman R, Hunter SK, et al. Prenatal Primary Prevention of Mental Illness by Micronutrient Supplements in Pregnancy. Am J Psychiatry. 2018 Jul 1;175(7):607-619.
AA5. Middleton P, Gomersall JC, et al. Omega-3 fatty acid addition during pregnancy. Cochrane Database Syst Rev. 2018 Nov 15;11:CD003402.
BB1. Upala S, Yong WC, et al. Effect of omega-3 fatty acids on disease severity in patients with psoriasis: A systematic review. Int J Rheum Dis. 2017 Apr;20(4):442-450.
BB2. Clark CCT, Taghizadeh M, et al. Efficacy of ω-3 supplementation in patients with psoriasis: a meta-analysis of randomized controlled trials. Clin Rheumatol. 2019 Apr;38(4):977-988.
CC1. Firth J, Rosenbaum S, et al. Adjunctive nutrients in first-episode psychosis: A systematic review of efficacy, tolerability and neurobiological mechanisms. Early Interv Psychiatry. 2018 Oct;12(5):774-783.
DD. Rheumatoid Arthritis
DD1. Proudman SM, James MJ, et al. Fish oil in recent onset rheumatoid arthritis: a randomised, double-blind controlled trial with algorithm-based drug use. Ann Rheum Dis. 2015;74(1):89-95.
DD2. Senftleber NK, Nielsen SM, et al. Marine Oil Supplements for Arthritis Pain: A Systematic Review and Meta-Analysis of Randomized Trials. Nutrients. 2017 Jan 6;9(1). pii: E42.
EE1. Chang CH, Tseng PT, et al. Safety and tolerability of prescription omega-3 fatty acids: A systematic review and meta-analysis of randomized controlled trials. Prostaglandins Leukot Essent Fatty Acids. 2018 Feb;129:1-12.
Last reviewed July 2019 by EBSCO NAT Review Board Eric Hurwitz, DC Last Updated: 5/6/2020