Omega-3 Nutrient Summary

Written by Olivia Farrow, RD, MHSc

Reviewed by Krista Kolodziejzyk, RD, MPH, MBA

This article will summarize the purpose of omega-3 in the body, food sources, and potential benefits of supplementation. 

Omega-3 fatty acids play a role in various bodily functions, such as forming cell membranes, supporting heart and brain health, reducing inflammation, and serving as a source of energy (1). The main types of omega-3s are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) (1).

For a full omega-3 evidence summary and supplement guide join Dietitian Success Center’s membership. The membership includes access to comprehensive yet simplified reference guides for supplements, food source lists, and client-facing handouts for many nutrients, including omega-3 and fish oils. 


Food Sources of Omega-3

ALA comes mostly from plant sources such as flaxseed, soybean, and canola oils, while DHA and EPA are primarily found in fatty fish, fish oil supplements, krill oil supplements, and algae (1). 

A comprehensive list of food sources of omega-3 can be found in DSC’s Food Sources of Nutrients Compilation.


Omega-3 Supplements

The potential health benefits of omega-3 and fish oil supplements has been studied widely. Some potential health benefits of omega-3 supplements include:

  • Heart Health: Omega-3 supplements may reduce coronary heart disease risk and triglycerides, but conflicting research exists (2). The American Heart Association recommends omega-3 intake for high-risk cardiovascular disease individuals (2).
  • Pregnancy and Child Health: DHA in omega-3 is crucial for infant brain development. Maternal seafood consumption during pregnancy and breastfeeding is linked to improved infant health and cognitive function (1). Omega-3 supplementation may also extend gestational length and reduce preterm birth risk (3,4).
  • Depression: High fish consumption correlates with lower depression risk, but the effect of omega-3 supplements on depressive symptoms is modest and uncertain (5).
  • Cognitive Function & Dementia: Observational studies suggest a link between omega-3 consumption and reduced dementia risk, but research on supplements shows no clear benefits for cognitive function or Alzheimer’s treatment (6,7).
  • Eye Health: Omega-3 supplements may help manage dry eye disease but don’t reduce the risk or progression of age-related macular degeneration (8).
  • Inflammatory Bowel Disease (IBD): Research does not support the use of omega-3 supplements for remission maintenance with  Crohn’s disease or ulcerative colitis (9,10).
  • Cancer: The impact of omega-3s on cancer prevention is inconclusive (1). Some studies suggest reduced breast and colorectal cancer risk, but more research is needed (1).
  • Attention Deficit Hyperactivity Disorder (ADHD): Omega-3 supplements show mixed results in alleviating symptoms of ADHD (11).


Key Takeaways

  • Omega-3 fatty acids are essential for various bodily functions, including cell membrane formation, heart and brain health, and inflammation reduction.
  • The main types of omega-3s are ALA (from plant sources), EPA, and DHA (primarily from fatty fish, fish oil, krill oil, and algae).
  • Omega-3 supplements may be considered for individuals with specific health conditions like high triglyceride levels, low omega-3 diets and pregnancy/breastfeeding.
  • Potential benefits of omega-3 supplements include heart health support, improved pregnancy outcomes, and relief from depression and ADHD symptoms, but evidence varies for other conditions like cognitive function, IBD, cancer prevention, and eye health.

Disclaimer: the information provided in all written materials is for educational purposes only and is not to be used as medical advice or to diagnose or treat a medical disease. It is strictly for informational purposes and is general in nature. Dietitian Success Center Inc. is not responsible and cannot be held liable for any actions or inactions taken related to the information provided. Consult with your local medical provider before implementing any dietary changes. It is hereby understood that the information provided does not replace medical advice provided by your healthcare provider.



  1. National Institutes of Health. “Omega-3 Fatty Acids – Health Professionals Fact Sheet”. Updated 2023. Available from
  2. Siscovick DS, et al. American Heart Association Nutrition Committee of the Council on Lifestyle and Cardiometabolic Health; Council on Epidemiology and Prevention; Council on Cardiovascular Disease in the Young; Council on Cardiovascular and Stroke Nursing; and Council on Clinical Cardiology. Omega-3 Polyunsaturated Fatty Acid (Fish Oil) Supplementation and the Prevention of Clinical Cardiovascular Disease: A Science Advisory From the American Heart Association. Circulation. 2017 Apr 11;135(15):e867-e884. doi: 10.1161/CIR.0000000000000482. Epub 2017 Mar 13. PMID: 28289069; PMCID: PMC6903779.
  3. Newberry SJ, Chung M, Booth M, Maglione MA, Tang AM, O’Hanlon CE, Wang DD, Okunogbe A, Huang C, Motala A, Trimmer M, Dudley W, Shanman R, Coker TR, Shekelle PG. Omega-3 Fatty Acids and Maternal and Child Health: An Updated Systematic Review. Evid Rep Technol Assess (Full Rep). 2016 Oct;(224):1-826. doi: 10.23970/AHRQEPCERTA224. PMID: 30307735.
  4. Middleton P, Gomersall JC, Gould JF, Shepherd E, Olsen SF, Makrides M. Omega-3 fatty acid addition during pregnancy. Cochrane Database Syst Rev. 2018 Nov 15;11(11):CD003402. doi: 10.1002/14651858.CD003402.pub3. PMID: 30480773; PMCID: PMC6516961.
  5. Appleton KM, Voyias PD, Sallis HM, Dawson S, Ness AR, Churchill R, Perry R. Omega-3 fatty acids for depression in adults. Cochrane Database Syst Rev. 2021 Nov 24;11(11):CD004692. doi: 10.1002/14651858.CD004692.pub5. PMID: 34817851; PMCID: PMC8612309.
  6. Sydenham E, Dangour AD, Lim WS. Omega 3 fatty acid for the prevention of cognitive decline and dementia. Cochrane Database Syst Rev. 2012 Jun 13;(6):CD005379. doi: 10.1002/14651858.CD005379.pub3. PMID: 22696350.
  7. Burckhardt M, Herke M, Wustmann T, Watzke S, Langer G, Fink A. Omega-3 fatty acids for the treatment of dementia. Cochrane Database Syst Rev. 2016 Apr 11;4(4):CD009002. doi: 10.1002/14651858.CD009002.pub3. PMID: 27063583; PMCID: PMC7117565.
  8. 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;2015(4):CD010015. doi: 10.1002/14651858.CD010015.pub3. PMID: 25856365; PMCID: PMC7087473.
  9. Lev-Tzion R, Griffiths AM, Leder O, Turner D. Omega 3 fatty acids (fish oil) for maintenance of remission in Crohn’s disease. Cochrane Database Syst Rev. 2014 Feb 28;2014(2):CD006320. doi: 10.1002/14651858.CD006320.pub4. PMID: 24585498; PMCID: PMC8988157.
  10. Turner D, Steinhart AH, Griffiths AM. Omega 3 fatty acids (fish oil) for maintenance of remission in ulcerative colitis. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD006443. doi: 10.1002/14651858.CD006443.pub2. PMID: 17636844.
  11. Cooper RE, Tye C, Kuntsi J, Vassos E, Asherson P. The effect of omega-3 polyunsaturated fatty acid supplementation on emotional dysregulation, oppositional behaviour and conduct problems in ADHD: A systematic review and meta-analysis. J Affect Disord. 2016 Jan 15;190:474-482. doi: 10.1016/j.jad.2015.09.053. Epub 2015 Oct 29. PMID: 26551407.

Get your FREE Nutrition Client Resource Kit to access a client-facing handout with common food sources of omega-3. 

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