Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Meta-Analysis
. 2004 Oct 18:(4):CD003177.
doi: 10.1002/14651858.CD003177.pub2.

Omega 3 fatty acids for prevention and treatment of cardiovascular disease

L Hooper  1 , R L Thompson, R A Harrison, C D Summerbell, H Moore, H V Worthington, P N Durrington, A R Ness, N E Capps, G Davey Smith, R A Riemersma, S B J Ebrahim
Affiliations
Meta-Analysis

Omega 3 fatty acids for prevention and treatment of cardiovascular disease

L Hooper et al. Cochrane Database Syst Rev. .

Update in

Abstract

Background: It has been suggested that omega 3 (W3, n-3 or omega-3) fats from oily fish and plants are beneficial to health.

Objectives: To assess whether dietary or supplemental omega 3 fatty acids alter total mortality, cardiovascular events or cancers using both RCT and cohort studies.

Search strategy: Five databases including CENTRAL, MEDLINE and EMBASE were searched to February 2002. No language restrictions were applied. Bibliographies were checked and authors contacted.

Selection criteria: RCTs were included where omega 3 intake or advice was randomly allocated and unconfounded, and study duration was at least six months. Cohorts were included where a cohort was followed up for at least six months and omega 3 intake estimated.

Data collection and analysis: Studies were assessed for inclusion, data extracted and quality assessed independently in duplicate. Random effects meta-analysis was performed separately for RCT and cohort data.

Main results: Forty eight randomised controlled trials (36,913 participants) and 41 cohort analyses were included. Pooled trial results did not show a reduction in the risk of total mortality or combined cardiovascular events in those taking additional omega 3 fats (with significant statistical heterogeneity). Sensitivity analysis, retaining only studies at low risk of bias, reduced heterogeneity and again suggested no significant effect of omega 3 fats. Restricting analysis to trials increasing fish-based omega 3 fats, or those increasing short chain omega 3s, did not suggest significant effects on mortality or cardiovascular events in either group. Subgroup analysis by dietary advice or supplementation, baseline risk of CVD or omega 3 dose suggested no clear effects of these factors on primary outcomes. Neither RCTs nor cohorts suggested increased relative risk of cancers with higher omega 3 intake but estimates were imprecise so a clinically important effect could not be excluded.

Reviewers' conclusions: It is not clear that dietary or supplemental omega 3 fats alter total mortality, combined cardiovascular events or cancers in people with, or at high risk of, cardiovascular disease or in the general population. There is no evidence we should advise people to stop taking rich sources of omega 3 fats, but further high quality trials are needed to confirm suggestions of a protective effect of omega 3 fats on cardiovascular health. There is no clear evidence that omega 3 fats differ in effectiveness according to fish or plant sources, dietary or supplemental sources, dose or presence of placebo.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Flow diagram for review.
Figure 2
Figure 2
Funnel plot of RCTs contributing data on total mortality (fixed effects meta-analysis). Note: the SE(log RR)s are negative.
Figure 3
Figure 3
Funnel plot of RCTs contributing data on total mortality (fixed effects meta-analysis) with studies reporting fewer than 50 deaths in total excluded. Note: the SE(log RR)s are negative.
See this image and copyright information in PMC

Comment in

References

References to studies included in this review

    1. Almallah YZ, Ewen SW, El Tahir A, Mowat NA, Brunt PW, Sinclair TS, et al. Distal proctocolitis and n-3 polyunsaturated fatty acids (n-3 PUFAs): the mucosal effect in situ. Journal of Clinical Immunology. 2000;20(1):68–76. - PubMed
    2. Almallah YZ, Ewen SW, Mowat NA, Brunt PW, Sinclair TS, Heys SD, et al. Immunohistological modulation after nutritional supplementation with omega-3 essential fatty acids in patients with inflammatory bowel disease [abstract] British Juurnal of Surgery. 1998;85:690–1.
    3. Almallah YZ, O’Hanrahan T, Richardson S, Mowat NA, Brunt PW, Sinclair TS, et al. Eicosapentaenoic acid and docosahexaenic acid in the treatment of patients with distal procto-colitis [abstract] British Journal of Surgery. 1996;83(Suppl 1):2.
    4. Almallah YZ, O’Hanrahan T, Richardson S, Mowat NA, Brunt PW, Sinclair TS, et al. Inhibition of natural cytotoxicity with eicosapentaenoic and docosahexaenoic acids: possible mechanisms [abstract] British Journal of Surgery. 1996;83:685.

    5. *

    6. Almallah YZ, Richardson S, O’Hanrahan T, Mowat NA, Brunt PW, Sinclair TS, et al. Distal procto-colitis, natural cytotoxicity, and essential fatty acids. American Journal of Gastroenterology. 1998;93(5):804–9. - PubMed
    1. Bairati I, Roy L, Meyer F. Double-blind, randomized, controlled trial of fish oil supplements in prevention of recurrence of stenosis after coronary angioplasty. Circulation. 1992;85(3):950–6. - PubMed
    2. Bairati I, Roy L, Meyer F. Effects of a fish oil supplement on blood pressure and serum lipids in patients treated for coronary artery disease. Canadian Journal of Cardiology. 1992;8(1):41–6. - PubMed
    3. Bairati I, Roy L, Meyer F. Measurement errors in standard visual analysis of coronary angiograms: consequences on clinical trials. Canadian Journal of Cardiology. 1993;9(3):225–30. - PubMed
    4. Meyer F, Bairati I, Roy L. Preventing restenosis after angioplasty with fish oil supplements. Cardiology Board Review. 1993;10(1):16+23–16+25.
    5. Roy L, Bairati I, Meyer F, et al. Double blind randomised controlled trial of fish oil supplements in the prevention of restenoses after coronary angioplasty. Circulation. 1991;84(supplement II):365. - PubMed

    1. *

    2. Bellamy CM, Schofield PM, Faragher EB, Ramsdale DR. Can supplementation of diet with omega-3 polyunsaturated fatty acids reduce coronary angioplasty restenosis rate? European Heart Journal. 1992;13(12):1626–31. - PubMed

    1. *

    2. Belluzzi A, Brignola C, Campieri M, Pera A, Boschi S, Miglioli M. Effect of an enteric-coated fish-oil preparation on relapses in Crohn’s disease. New England Journal of Medicine. 1996 Jun 13;334(24):1557–60. - PubMed
    1. Bemelmans WJ, Broer J, de Vries JH, Hulshof KF, May JF, Meyboom-De Jong B. Impact of Mediterranean diet education versus posted leaflet on dietary habits and serum cholesterol in a high risk population for cardiovascular disease. Public Health Nutrition. 2000;3(3):273–83. - PubMed

    2. *

    3. Bemelmans WJ, Broer J, Feskens EJ, Smit AJ, Muskiet AJ, Lefrandt JD, et al. Effect of an increased intake of alpha-linolenic acid and group nutritional education on cardiovascular risk factors: the Mediterranean alpha-linolenic enriched Groningen dietary intervention (MARGARIN) study. American Journal of Clinical Nutrition. 2002;75:221–7. - PubMed

References to studies excluded from this review

    1. Alekseeva RI, Sharafetdinov KK, Plotnikova OA, Meshcheriakova VA, Mal’tsev GI, Kulakova SN. 463Effects of diet therapy including eiconol on clinical and metabolic parameters in patients with type 2 diabetes mellitus]. [Russian] Voprosy Pitaniia. 2000;69(5):36–9. - PubMed
    1. Alekseeva RI, Sharafetdinov K, Plotnikova OA, Meshcheriakova VA, Mal’tsev GI, Kulakova SN. [Effects of a diet including linseed oil on clinical and metabolic parameters in patients with type 2 diabetes mellitus]. [Russian] Voprosy Pitaniia. 2000;69(6):32–5. - PubMed
    1. Andreassen AK, Hartmann A, Offstad J, Geiran O, Kvernebo K, Simonsen S. Hypertension prophylaxis with omega-3 fatty acids in heart transplant recipients. Journal of the American College of Cardiology. 1997;29(6):1324–31. - PubMed
    1. Bard JM, Luc G, Jude B, Bordet JC, Lacroix B, Bonte JP, et al. A therapeutic dosage (3 g/day) of borage oil supplementation has no effect on platelet aggregation in healthy volunteers. Fundamental & Clinical Pharmacology. 1997;11(2):143–4. - PubMed
    1. Belch JJ, Ansell D, Madhok R, O’Dowd A, Sturrock RD. Effects of altering dietary essential fatty acids on requirements for non-steroidal anti-inflammatory drugs in patients with rheumatoid arthritis: a double blind placebo controlled study. Annals of the Rheumatic Diseases. 1988;47(2):96–104. - PMC - PubMed

References to studies awaiting assessment

    1. Bates D. Dietary lipids and multiple sclerosis. Upsala journal of medical sciences. 1990;48:173–87. - PubMed
    2. French JM. MaxEPA in multiple sclerosis. British Journal of Clinical Practice. 1984;31:117–21. - PubMed
    1. Belch JJF. Blood vessels and essential fatty acids. National Research Register. 2002;(Issue 3):N0405016313.
    1. Delamaire M, Durand F, Bouillaux M, Delambre C, Le-Goff MC, Allannic H. Influence of polyunsaturated fatty acid (MaxEPA) treatment on the haemorheological parameters of 28 IDD patients. Diabetologia. 1991;34:A74.
    1. Kremer JM, Lawrence DA, Petrillo GF, Litts LL, Mullaly PM, Rynes RI, et al. Effects of high-dose fish oil on rheumatoid arthritis after stopping nonsteroidal antiinflammatory drugs. Clinical and immune correlates. Arthritis and Rheumatism. 1995;38(8):1107–14. - PubMed

    1. *

    2. Kurabayashi T, Okada M, Tanaka K. Eicosapentaenoic acid effect on hyperlipidemia in menopausal Japanese women. The Niigata Epadel Study Group. Obstetrics & Gynecology. 2000;96(4):521–8. - PubMed

References to ongoing studies

    1. Atorvastatin in Factorial Combination with Omega 3 fatty acids in cardiovascular Risk Reduction in patients with type 2 Diabetes Ongoing study Starting date of trial not provided. Contact author for more information.
    1. A Study of Cardiovascular Events iN Diabetes (ASCEND) Ongoing study Starting date of trial not provided. Contact author for more information.
    1. Harrison RA, Elton P. From pies to pilchards: dietary assistants increase consumption of oil rich fish [Abstract] Journal of Epidemiology and Community Health. 2000;(Supplement):6. - PubMed
    2. Harrison RA, Elton PJ. International Society for the Study of Fatty Acids and Lipids (ISSFAL) Montreal, Canada: 2003. Can an oil-rich fish diet improve treatment outcomes following cardioversion for atrial fibrillation? A randomised controlled trial. Study design and compliance [poster]
    3. Harrison RA, Elton PJ. Is there a role for long-chain omega3 or oil-rich fish in the treatment of atrial fibrillation? Medical Hypotheses. 2004 Jun 9th; Accepted for publication. - PubMed
    4. Harrison RA, Purnell P, Elton PJ. Using community-based dietary assistants to increase the intake of oil-rich fish among older people [Abstract] European Journal of Public Health. 2003;13(Suppl 1):105. - PubMed
    1. GISSI-HF Ongoing study Starting date of trial not provided. Contact author for more information.

    1. *

    2. Yokoyama M, Origasa H, for teh JELIS Investigators Effects of eicosapentaenoic acid on cardiovascular events in Japanese patients with hypercholesterolaemia: Rationale, design, and baseline characteristics of the Japan EPA Lipid Intervention Study (JELIS) American Heart Journal. 2003;146:613–20. - PubMed

Additional references

    1. Appel LJ, Miller ER, Seidler AJ, Whelton PK. Does supplementation of diet with “fish oil” reduce blood pressure? A meta-analysis of controlled clinical trials. Archives of Internal Medicine. 1993;153:1429–38. - PubMed
    1. Ballard-Barbash R, Callaway CW. Marine fish oils: role in prevention of coronary artery disease. Mayo Clinic Proceedings. 1987;62:113–8. - PubMed
    1. Bang HO, Dyerberg J. Plasma lipids and lipoproteins in Greenlandic west coast eskimos. Acta Medica Scandinavica. 1972;192:85–94. - PubMed
    1. Bang HO, Dyerberg J, Hjorne N. The composition of food consumed by Greenland Eskimos. Acta medica Scandinavica. 1976;200:69–73. - PubMed
    1. Berkley CS, Hoaglin DC, Mosteller F, Colditz GA. A random-effects regression model for meta-analysis. Statistics in Medicine. 1995;14:395–411. - PubMed

MeSH terms

Substances