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Omega-3

Also known as Fish oil, Omega 3 fatty acids

Not medically reviewed

fatty acidentity:supplement:omega-3

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Ingredients and forms

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Ingredient identities

Eicosapentaenoic acidentity:ingredient:epa
Docosahexaenoic acidentity:ingredient:dha

Specific forms

EPAfatty acid
DHAfatty acid

Ingredient intelligence

Eicosapentaenoic acid (EPA)fatty acid
Docosahexaenoic acid (DHA)fatty acid

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Evidence source: NIH ODS evidence synthesis
Linked references: 23 identified
Human evidence: Human evidence identified
Randomized trials: Randomized trials not identified in the frozen metadata
Reviews and meta-analyses: Systematic reviews or meta-analyses not identified in the frozen metadata
Evidence recency: 2004–2015
Source-described consistency: Not characterized in these source blocks
MEDucated evidence rating: Not assigned

Reference counts describe frozen source associations; a larger count does not establish stronger evidence.

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Evidence types identified

Study type could not be determined22
Government reference1

Source-described limitations

No explicit limitation phrase was identified in these imported source blocks.

Classified references

Jones PJH, Rideout T. Lipids, sterols, and their metabolites. In: Ross AC, Caballero B, Cousins RJ, Tucker KL, Ziegler TR, eds. Modern Nutrition in Health and Disease. 11th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014.
Study type could not be determined · Population basis: unknown · Directness: not assessed
Jones PJH, Papamandjaris AA. Lipids: cellular metabolism. In: Erdman JW, Macdonald IA, Zeisel SH, eds. Present Knowledge in Nutrition. 10th ed. Washington, DC: Wiley-Blackwell; 2012:132-48.
Study type could not be determined · Population basis: unknown · Directness: not assessed
Harris WS. Omega-3 fatty acids. In: Coates PM, Betz JM, Blackman MR, et al., eds. Encyclopedia of Dietary Supplements. 2nd ed. London and New York: Informa Healthcare; 2010:577-86.
Study type could not be determined · Population basis: unknown · Directness: not assessed
Lichtenstein AH, Jones PJH. Lipids: absorption and transport. In: Erdman JW, Macdonald IA, Zeisel SH, eds. Present Knowledge in Nutrition. 10th ed. Washington, DC: Wiley-Blackwell; 2012:118-31.
Study type could not be determined · Population basis: unknown · Directness: not assessed
Institute of Medicine, Food and Nutrition Board. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). Washington, DC: National Academy Press; 2005.
Government reference · Population basis: unknown · Directness: not assessed
SanGiovanni JP, Chew EY. The role of omega-3 long-chain polyunsaturated fatty acids in health and disease of the retina. Prog Retin Eye Res 2005;24:87-138. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Gabbs M, Leng S, Devassy JG, Monirujjaman M, Aukema HM. Advances in our understanding of oxylipins derived from dietary PUFAs. Adv Nutr 2015;6:513-40. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Simopoulos AP. The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Exp Biol Med 2008;233:674-88. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
James M, Proudman S, Cleland L. Fish oil and rheumatoid arthritis: past, present and future. Proc Nutr Soc 2010;69:316-23. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Wang C, Chung M, Lichtenstein A, Balk E, Kupelnick B, DeVine D, et al. Effects of omega-3 fatty acids on cardiovascular disease. Summary, evidence report/technology assessment no. 94. (Prepared by the Tufts New England Medical Center Evidence-based Practice Center, Boston, MA.) AHRQ Publication No. 04-E009-1. Agency for Healthcare Research and Quality, 2004.
Study type could not be determined · Population basis: unknown · Directness: not assessed
Stanley JC, Elsom RL, Calder PC, Griffin BA, Harris WS, Jebb SA, et al. UK Food Standards Agency workshop report: the effects of the dietary n-6:n-3 fatty acid ratio on cardiovascular health. Br J Nutr 2007;98:1305-10. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Harris WS, Davidson MH. RE: Plasma phospholipid fatty acids and prostate cancer risk in the SELECT trial. J Natl Cancer Inst 2014;106:dju019. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Fritsche KL. Too much linoleic acid promotes inflammation-doesn't it? Prostaglandins Leukot Essent Fatty Acids 2008;79:173-5. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Brasky TM, Till C, White E, Neuhouser ML, Song X, Goodman P, et al. Serum phospholipid fatty acids and prostate cancer risk: results from the prostate cancer prevention trial. Am J Epidemiol 2011;173:1429-39. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Brasky TM, Darke AK, Song X, Tangen CM, Goodman PJ, Thompson IM, et al. Plasma phospholipid fatty acids and prostate cancer risk in the SELECT trial. J Natl Cancer Inst 2013;105:1132-41. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Harris WS, Sands SA, Windsor SL, Ali HA, Stevens TL, Magalski A, et al. Omega-3 fatty acids in cardiac biopsies from heart transplantation patients: correlation with erythrocytes and response to supplementation. Circulation 2004;110:1645-9. [PubMed abstract]
Study type could not be determined · Population basis: human · Directness: not assessed
Harris WS. Are n-3 fatty acids still cardioprotective? Curr Opin Clin Nutr Metab Care 2013;16:141-9. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Sun Q, Ma J, Campos H, Hankinson SE, Hu FB. Comparison between plasma and erythrocyte fatty acid content as biomarkers of fatty acid intake in US women. Am J Clin Nutr 2007;86:74-81. [PubMed abstract]
Study type could not be determined · Population basis: human · Directness: not assessed
Agency for Healthcare Research and Quality. Omega-3 fatty acids and cardiovascular disease - update. 2015.
Study type could not be determined · Population basis: unknown · Directness: not assessed
Harris WS, Von Schacky C. The Omega-3 Index: a new risk factor for death from coronary heart disease? Prev Med 2004;39:212-20. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Harris WS. The omega-3 index as a risk factor for coronary heart disease. Am J Clin Nutr 2008;87:1997S-2002S. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Metcalf RG, Cleland LG, Gibson RA, Roberts-Thomson KC, Edwards JR, Sanders P, et al. Relation between blood and atrial fatty acids in patients undergoing cardiac bypass surgery. Am J Clin Nutr 2010;91:528-34. [PubMed abstract]
Study type could not be determined · Population basis: human · Directness: not assessed
von Schacky C. Use of red blood cell fatty-acid profiles as biomarkers in cardiac disease. Biomark Med 2009;3:25-32. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed

Read imported source wording

The two major classes of polyunsaturated fatty acids (PUFAs) are the omega-3 and omega-6 fatty acids. Like all fatty acids, PUFAs consist of long chains of carbon atoms with a carboxyl group at one end of the chain and a methyl group at the other. PUFAs are distinguished from saturated and monounsaturated fatty acids by the presence of two or more double bonds between carbons within the fatty acid chain.

Omega-3 fatty acids (omega-3s) have a carbon–carbon double bond located three carbons from the methyl end of the chain. Omega-3s, sometimes referred to as n-3s, are present in certain foods such as flaxseed and fish as well as dietary supplements such as fish oil. Several different omega-3s exist, but the majority of scientific research focuses on three: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA contains 18 carbon atoms, whereas EPA and DHA are considered long-chain (LC) omega-3s because EPA contains 20 carbons and DHA contains 22.

PUFAs are frequently designated by their number of carbon atoms and double bonds. ALA, for example, is known as C18:3n-3 because it has 18 carbons and 3 double bonds and is an n-3, or omega-3, fatty acid. Similarly, EPA is known as C20:5n-3 and DHA as C22:6n-3. Omega-6 fatty acids (omega-6s) have a carbon–carbon double bond that is six carbons away from the methyl end of the fatty acid chain. Linoleic acid (C18:2n-6) and arachidonic acid (C20:4n-6) are two of the major omega-6s.

The human body can only form carbon–carbon double bonds after the ninth carbon from the methyl end of a fatty acid [1]. Therefore, ALA and linoleic acid are considered essential fatty acids, meaning that they must be obtained from the diet [2]. ALA can be converted into EPA and then to DHA, but the conversion (which occurs primarily in the liver) is very limited, with reported rates of less than 15% [3]. Therefore, consuming EPA and DHA directly from foods and/or dietary supplements is the only practical way to increase levels of these fatty acids in the body.

ALA is present in plant oils, such as flaxseed, soybean, and canola oils [3]. DHA and EPA are present in fish, fish oils, and krill oils, but they are originally synthesized by microalgae at the base of the marine food chain, not by the fish. As microalgae move up the food chain, fish acquire the omega-3s and accumulate them in their tissues [3].

After ingestion, dietary lipids are hydrolyzed in the intestinal lumen [1]. The hydrolysis products—monoglycerides and free fatty acids—are then incorporated into bile-salt– containing micelles and absorbed into enterocytes, largely by passive diffusion. The process is efficient, with an absorption rate of about 95%, which is similar to that of other ingested fats [1]. Within intestinal cells, free fatty acids are primarily incorporated into chylomicrons and enter the circulation via the lymphatic system [1,4]. Once in the bloodstream, lipoprotein particles circulate within the body, delivering lipids to various organs for subsequent oxidation, metabolism, or storage in adipose tissue [4,5].

Omega-3s play important roles in the body as components of the phospholipids that form the structures of cell membranes [5]. DHA, in particular, is especially high in the retina, brain, and sperm [3,5,6]. In addition to their structural role in cell membranes, omega-3s (along with omega-6s) provide energy for the body and are used to form eicosanoids. Eicosanoids are signaling molecules that have similar chemical structures to the fatty acids from which they are derived; they have wide-ranging functions in the body's cardiovascular, pulmonary, immune, and endocrine systems [1,2].

The eicosanoids made from omega-6s are generally more potent mediators of inflammation, vasoconstriction, and platelet aggregation than those made from omega-3s, although there are some exceptions [3,7]. Because both classes of fatty acids compete for the same desaturation enzymes, ALA is a competitive inhibitor of linoleic acid metabolism and vice versa [8]. Similarly, EPA and DHA can compete with arachidonic acid for the synthesis of eicosanoids. Thus, higher concentrations of EPA and DHA than arachidonic acid tip the eicosanoid balance toward less inflammatory activity [9].

Some researchers propose that the relative intakes of omega-6s and omega-3s—the omega-6/omega-3 ratio—may have important implications for the pathogenesis of many chronic diseases, such as cardiovascular disease (CVD) and cancer [8], but the optimal ratio—if any—has not been defined [10]. Others have concluded that such ratios are too nonspecific and are insensitive to individual fatty acid levels [11-13]. Most agree that raising EPA and DHA blood levels is far more important than lowering linoleic acid or arachidonic acid levels.

Currently, most clinicians do not assess omega-3 status, but it can be done by measuring individual omega-3s in plasma or serum phospholipids and expressing them as the percentage of total phospholipid fatty acids by weight [14-16]. Experts have not established normal ranges, but mean values for serum or plasma phospholipid EPA plus DHA among U.S. adults not taking omega-3 supplements are about 3%–4% [14-16]. Plasma and serum fatty acid values, however, can vary substantially based on an individual's most recent meal, so they do not reflect long-term dietary consumption [3,17].

It is also possible to assess omega-3 status via analysis of erythrocyte fatty acids, a measurement that reflects longer term intakes over approximately the previous 120 days [18,19]. The omega-3 index proposed by Harris and von Schacky reflects the content of EPA plus DHA in erythrocyte membranes expressed as a percentage of total erythrocyte fatty acids [20,21]. This index can be used as a surrogate for assessing tissue levels of EPA plus DHA [16,22,23]. EPA and DHA typically comprise about 3%–5% of erythrocyte fatty acids in Western populations with low fish intakes. In Japan, where fish consumption is high, erythrocyte EPA and DHA levels are about twice those of Western populations [3].

Where did MEDucated get this?

Omega-3 Fatty Acids — Fact Sheet for Health Professionals

NIH Office of Dietary Supplements. Government health-professional reference material imported without MEDucated medical review.

Source section: Introduction
ODS revision: August 22, 2025
Retrieved: 2026-08-10T22:07:06.488Z
Source fingerprint: 80b4434afaf71303420a09ab193258a2d656c3bdec58a108fe3d14961d1bb750
Cited reference numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23

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Known risks and safety considerations

Imported NIH ODS source content is available for this topic. MEDucated has preserved the source wording and has not converted it into personalized guidance.

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Evidence profile

No overall rating assigned

Evidence source: NIH ODS evidence synthesis
Linked references: 7 identified
Human evidence: Human evidence identified
Randomized trials: Randomized trial identified
Reviews and meta-analyses: Systematic review or meta-analysis identified
Evidence recency: 2005–2020
Source-described consistency: Not characterized in these source blocks
MEDucated evidence rating: Not assigned

Reference counts describe frozen source associations; a larger count does not establish stronger evidence.

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Evidence types identified

Government reference1
Study type could not be determined3
Randomized controlled trial1
Meta-analysis1
Regulatory source1

Source-described limitations

No explicit limitation phrase was identified in these imported source blocks.

Classified references

Institute of Medicine, Food and Nutrition Board. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). Washington, DC: National Academy Press; 2005.
Government reference · Population basis: unknown · Directness: not assessed
Bhatt DL, Steg PG, Miller M, Brinton EA, Jacobson TA, et al; REDUCE-IT Investigators. Cardiovascular risk reduction with icosapent ethyl for hypertriglyceridemia. N Engl J Med 2019;380:11-22. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Nicholls SJ, Lincoff M, Garcia M, Dash D, Ballantyne CM, Barter PJ, et al. Effect of high-dose omega-3 fatty acids vs corn oil on major adverse cardiovascular events in patients at high cardiovascular risk. The STRENGTH randomized clinical trial. JAMA 2020;324:2268-80. [PubMed abstract]
Randomized controlled trial · Population basis: human · Directness: not assessed
Mazereeuw G, Lanctot KL, Chau SA, Swardfager W, Herrmann N. Effects of omega-3 fatty acids on cognitive performance: a meta-analysis. Neurobiol Aging 2012;33:1482 e17-29. [PubMed abstract]
Meta-analysis · Population basis: unknown · Directness: not assessed
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;2:CD006320. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
EFSA Panel on Dietetic Products NaA. Scientific opinion on the tolerable upper intake level of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA). EFSA Journal 2012;10:2815.
Study type could not be determined · Population basis: unknown · Directness: not assessed
U.S. Food and Drug Administration. Qualified health claims: letters of enforcement discretion. 2019.
Regulatory source · Population basis: unknown · Directness: not assessed

For most macronutrients, the IOM has established an acceptable macronutrient distribution range (AMDR) that suggests an acceptable range of intake. The AMDR for total fat intake, for example, is based on adverse effects from either very low fat or very high fat diets. The IOM established an AMDR for omega-3s (as ALA) of 0.6% to 1.2% of energy for children and adults age 1 year and older [5]. The IOM also noted that about 10% of the AMDR can be consumed as EPA and/or DHA.

The IOM did not establish a UL for any omega-3s, although it noted that high doses of DHA and/or EPA (900 mg/day of EPA plus 600 mg/day DHA or more for several weeks) might reduce immune function due to suppression of inflammatory responses. Doses of 2–15 g/day EPA and/or DHA might also increase bleeding time by reducing platelet aggregation [5]. However, according to the European Food Safety Authority, long-term consumption of EPA and DHA supplements at combined doses of up to about 5 g/day appears to be safe [195]. It noted that these doses have not been shown to cause bleeding problems or affect immune function, glucose homeostasis, or lipid peroxidation. Similarly, FDA has concluded that dietary supplements providing no more than 5 g/day EPA and DHA are safe when used as recommended [196]. Two large clinical trials completed after these assessments found that taking 4 g/day of omega-3 supplements for several years slightly increased the risk of atrial fibrillation in people with CVD or at high risk of CVD [63,64].

UL reference intakeSource intake rangeSource-described amount

Commonly reported side effects of omega-3 supplements are usually mild. These include unpleasant taste, bad breath, heartburn, nausea, gastrointestinal discomfort, diarrhea, headache, and odoriferous sweat [161,190].

Where did MEDucated get this?

Omega-3 Fatty Acids — Fact Sheet for Health Professionals

NIH Office of Dietary Supplements. Government health-professional reference material imported without MEDucated medical review.

Source section: Safety of Omega-3s
ODS revision: August 22, 2025
Retrieved: 2026-08-10T22:07:06.488Z
Source fingerprint: 80b4434afaf71303420a09ab193258a2d656c3bdec58a108fe3d14961d1bb750
Cited reference numbers: 5, 63, 64, 195, 196, 161, 190

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Imported NIH ODS source content is available for this topic. MEDucated has preserved the source wording and has not converted it into personalized guidance.

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Structural characterization

Evidence profile

No overall rating assigned

Evidence source: NIH ODS evidence synthesis
Linked references: 6 identified
Human evidence: Human evidence identified
Randomized trials: Randomized trials not identified in the frozen metadata
Reviews and meta-analyses: Systematic reviews or meta-analyses not identified in the frozen metadata
Evidence recency: 1998–2015
Source-described consistency: Not characterized in these source blocks
MEDucated evidence rating: Not assigned

Reference counts describe frozen source associations; a larger count does not establish stronger evidence.

Inspect technical evidence details

Evidence types identified

Study type could not be determined6

Source-described limitations

No explicit limitation phrase was identified in these imported source blocks.

Classified references

Natural Medicines Comprehensive Database. Fish Oil. 2015.
Study type could not be determined · Population basis: unknown · Directness: not assessed
Svaneborg N, Kristensen SD, Hansen LM, Bullow I, Husted SE, Schmidt EB. The acute and short-time effect of supplementation with the combination of n-3 fatty acids and acetylsalicylic acid on platelet function and plasma lipids. Thromb Res 2002;105:311-6. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Buckley MS, Goff AD, Knapp WE. Fish oil interaction with warfarin. Ann Pharmacother 2004;38:50-2 [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Bender NK, Kraynak MA, Chiquette E, Linn WD, Clark GM, Bussey HI. Effects of marine fsh oils on the anticoagulation status of patients receiving chronic warfarin therapy. J Thromb Thrombolysis 1998;5:257-61. [PubMed abstract]
Study type could not be determined · Population basis: human · Directness: not assessed
Wachira JK, Larson MK, Harris WS. n-3 fatty acids affect haemostasis but do not increase the risk of bleeding: clinical observations and mechanistic insights. Br J Nutr 2014;111:1652-62. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
GlaxoSmithKline. LOVAZA® (omega-3 acid ethyl esters) capsules, prescribing information. 2008.
Study type could not be determined · Population basis: unknown · Directness: not assessed

Omega-3 dietary supplements, such as fish oil, have the potential to interact with medications. One example is provided below. People taking these and other medications on a regular basis should discuss possible interactions with their health care providers.

Fish oil can have antiplatelet effects at high doses, although it appears to be less potent than aspirin [197,198]. Fish oil might prolong clotting times, as indicated by an elevated international normalized ratio (INR), when it is taken with warfarin [199], but most research indicates that doses of 3–6 g/day fish oil do not significantly affect the anticoagulant status of patients taking warfarin [200]. The authors of a 2014 review concluded that omega-3s do not affect the risk of clinically significant bleeding [201], and the FDA-approved package inserts for omega-3 pharmaceuticals state that studies with omega-3s have not produced "clinically significant bleeding episodes" [202]. However, these package inserts also state that patients taking these products with anticoagulants should be monitored periodically for changes in INR.

Source intake rangeSource-described amount

Where did MEDucated get this?

Omega-3 Fatty Acids — Fact Sheet for Health Professionals

NIH Office of Dietary Supplements. Government health-professional reference material imported without MEDucated medical review.

Source section: Interactions with Medications
ODS revision: August 22, 2025
Retrieved: 2026-08-10T22:07:06.488Z
Source fingerprint: 80b4434afaf71303420a09ab193258a2d656c3bdec58a108fe3d14961d1bb750
Cited reference numbers: 197, 198, 199, 200, 201, 202

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Imported NIH ODS source content is available for this topic. MEDucated has preserved the source wording and has not converted it into personalized guidance.

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Evidence profile

No overall rating assigned

Evidence source: NIH ODS evidence synthesis
Linked references: 14 identified
Human evidence: Human evidence identified
Randomized trials: Randomized trial identified
Reviews and meta-analyses: Systematic reviews or meta-analyses not identified in the frozen metadata
Evidence recency: 2008–2016
Source-described consistency: Not characterized in these source blocks
MEDucated evidence rating: Not assigned

Reference counts describe frozen source associations; a larger count does not establish stronger evidence.

Inspect technical evidence details

Evidence types identified

Study type could not be determined11
Regulatory source1
Randomized controlled trial2

Source-described limitations

No explicit limitation phrase was identified in these imported source blocks.

Classified references

National Institutes of Health. Dietary Supplement Label Database. 2015.
Study type could not be determined · Population basis: unknown · Directness: not assessed
U.S. Food and Drug Administration. Fish: what pregnant women and parents should know. 2014.
Regulatory source · Population basis: human · Directness: not assessed
ConsumerLab.com. Product review: fish oil and omega-3 fatty acid supplements review (including krill, algae, calamari, green-lipped mussel oil). 2016.
Study type could not be determined · Population basis: unknown · Directness: not assessed
Dyerberg J, Madsen P, Moller JM, Aardestrup I, Schmidt EB. Bioavailability of marine n-3 fatty acid formulations. Prostaglandins Leukot Essent Fatty Acids 2010;83:137-41. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Cunningham E. Are krill oil supplements a better source of n-3 fatty acids than fish oil supplements? J Acad Nutr Diet 2012;112:344. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Davidson MH, Kling D, Maki KC. Novel developments in omega-3 fatty acid-based strategies. Curr Opin Lipidol 2011;22:437-44. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Schuchardt JP, Schneider I, Meyer H, Neubronner J, von Schacky C, Hahn A. Incorporation of EPA and DHA into plasma phospholipids in response to different omega-3 fatty acid formulations--a comparative bioavailability study of fish oil vs. krill oil. Lipids Health Dis 2011;10:145. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Ulven SM, Holven KB. Comparison of bioavailability of krill oil versus fish oil and health effect. Vasc Health Risk Manag 2015;11:511-24. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Ramprasath VR, Eyal I, Zchut S, Jones PJ. Enhanced increase of omega-3 index in healthy individuals with response to 4-week n-3 fatty acid supplementation from krill oil versus fish oil. Lipids Health Dis 2013;12:178. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Ulven SM, Kirkhus B, Lamglait A, Basu S, Elind E, et al. Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteers. Lipids 2011;46(1):37-46. [PubMed abstract]
Study type could not be determined · Population basis: human · Directness: not assessed
Salem N Jr, Kuratko CN. A reexamination of krill oil bioavailability studies. Lipids Health Dis 2014;13:137. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Yurko-Mauro K, Kralovec J, Bailey-Hall E, Smeberg V, Stark JG, et al. Similar eicosapentaenoic acid and docosahexaenoic acid plasma levels achieved with fish oil or krill oil in a randomized double-blind four-week bioavailability study. Lipids Health Dis 2015;14:99. [PubMed abstract]
Randomized controlled trial · Population basis: unknown · Directness: not assessed
Köhler A, Sarkkinen E, Tapola N, Niskanen T, Bruheim I. Bioavailability of fatty acids from krill oil, krill meal and fish oil in healthy subjects--a randomized, single-dose, cross-over trial. Lipids Health Dis 2015;14:19. [PubMed abstract]
Randomized controlled trial · Population basis: unknown · Directness: not assessed
Arterburn LM, Oken HA, Bailey Hall E, Hamersley J, Kuratko CN, Hoffman JP. Algal-oil capsules and cooked salmon: nutritionally equivalent sources of docosahexaenoic acid. J Am Diet Assoc 2008;108:1204-9. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed

Read imported source wording

LC omega-3s are present in several dietary supplement formulations, including fish oil, krill oil, cod liver oil, and vegetarian products that contain algal oil. A typical fish oil supplement provides about 1,000 mg fish oil, containing 180 mg EPA and 120 mg DHA, but doses vary widely [30]. Cod liver oil supplements provide vitamin A and vitamin D in addition to LC omega-3s. Although seafood contains varying levels of methyl mercury (a toxic heavy metal) [31], omega-3 supplements have not been found to contain this contaminant because it is removed during processing and purification [32].

Source-described amount

Dietary supplements can contain several different forms of omega-3s, including natural triglycerides, free fatty acids, ethyl esters, re-esterified triglycerides, and phospholipids [32-34]. Natural triglycerides are the form that occur naturally in fish oil, whereas ethyl esters are synthesized from natural triglycerides by replacement of the glycerol molecule of the triglyceride with ethanol. Re-esterified triglycerides are formed by the conversion of ethyl esters back to triglycerides. Omega-3s as re-esterified triglycerides, natural triglycerides, and free fatty acids have somewhat higher bioavailability than ethyl esters, but consumption of all forms significantly increases plasma EPA and DHA levels [33,35].

Krill oil contains omega-3s primarily as phospholipids. Some studies suggest that these phospholipids have somewhat higher bioavailability than the omega-3s in fish oil, whereas other studies do not [34,36,37,38,39,40,41,42].

Plant-based sources of omega-3s from algal oil usually provide around 100–300 mg DHA; some contain EPA as well. These supplements typically contain omega-3s in the triglyceride form [32]. According to a small study, the bioavailability of DHA from algal oil is equivalent to that from cooked salmon [43].

Source intake rangeSource-described amount

Formulations of omega-3 dietary supplements vary widely, so it is important to check product labels to determine the types and amounts of omega-3s in these products. The Dietary Supplement Label Database from the National Institutes of Health contains label information from many dietary supplements on the market that contain omega-3s.

Where did MEDucated get this?

Omega-3 Fatty Acids — Fact Sheet for Health Professionals

NIH Office of Dietary Supplements. Government health-professional reference material imported without MEDucated medical review.

Source section: Dietary Supplements
ODS revision: August 22, 2025
Retrieved: 2026-08-10T22:07:06.488Z
Source fingerprint: 80b4434afaf71303420a09ab193258a2d656c3bdec58a108fe3d14961d1bb750
Cited reference numbers: 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43

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Evidence recency: 2005–2005
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When the IOM last reviewed omega-3s, insufficient data were available to establish an EAR, so the IOM established AIs for all ages based on omega-3 intakes in healthy populations [5].

Classified references

Institute of Medicine, Food and Nutrition Board. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). Washington, DC: National Academy Press; 2005.
Government reference · Population basis: unknown · Directness: not assessed

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Intake recommendations for fatty acids and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board of the Institute of Medicine (IOM) (now called the National Academy of Medicine) [5]. DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. These values, which vary by age and sex, include the following:

Recommended Dietary Allowance (RDA): Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals; often used to plan nutritionally adequate diets for individuals
Adequate Intake (AI): Intake at this level is assumed to ensure nutritional adequacy; established when evidence is insufficient to develop an RDA
Estimated Average Requirement (EAR): Average daily level of intake estimated to meet the requirements of 50% of healthy individuals; usually used to assess the nutrient intakes of groups of people and to plan nutritionally adequate diets for them; can also be used to assess the nutrient intakes of individuals
Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse health effects

RDA reference intakeAI reference intakeUL reference intake

When the IOM last reviewed omega-3s, insufficient data were available to establish an EAR, so the IOM established AIs for all ages based on omega-3 intakes in healthy populations [5].

Table 1 lists the current AIs for omega-3s in grams per day. Human milk contains omega-3s as ALA, EPA, and DHA, so the IOM established an AI for infants from birth to 12 months that is equivalent to the mean intake of omega-3s in healthy, breastfed infants.

AI reference intake

For infants, the AIs apply to total omega-3s. For age 1 and older, the AIs apply only to ALA because ALA is the only omega-3 that is essential. The IOM did not establish specific intake recommendations for EPA, DHA, or other LC omega-3s.

Table 1: Adequate Intakes (AIs) for Omega-3s [5]
Age	Male	Female	Pregnancy	Lactation
Birth to 6 months*	0.5 g	0.5 g
7–12 months*	0.5 g	0.5 g
1–3 years**	0.7 g	0.7 g
4–8 years**	0.9 g	0.9 g
9–13 years**	1.2 g	1.0 g
14–18 years**	1.6 g	1.1 g	1.4 g	1.3 g
19–50 years**	1.6 g	1.1 g	1.4 g	1.3 g
51+ years**	1.6 g	1.1 g

AI reference intakeSource-described amount

*As total omega-3s **As ALA

Where did MEDucated get this?

Omega-3 Fatty Acids — Fact Sheet for Health Professionals

NIH Office of Dietary Supplements. Government health-professional reference material imported without MEDucated medical review.

Source section: Recommended Intakes
ODS revision: August 22, 2025
Retrieved: 2026-08-10T22:07:06.488Z
Source fingerprint: 80b4434afaf71303420a09ab193258a2d656c3bdec58a108fe3d14961d1bb750
Cited reference numbers: 5

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Evidence source: NIH ODS evidence synthesis
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Classified references

Institute of Medicine, Food and Nutrition Board. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). Washington, DC: National Academy Press; 2005.
Government reference · Population basis: unknown · Directness: not assessed

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Evidence that higher LC omega-3 levels are associated with a reduced risk of several chronic diseases, including coronary heart disease, suggests that many Americans could benefit from slightly higher intakes. However, classical essential fatty acid deficiency in healthy individuals in the United States is virtually nonexistent [5]. During periods of dietary-fat restriction or malabsorption accompanied by an energy deficit, the body releases essential fatty acids from adipose-tissue reserves. For this reason, clinical signs of essential fatty-acid deficiency are usually only found in patients receiving parenteral nutrition that lacks PUFAs. This was documented in case reports during the 1970s and 1980s [5], but all current enteral and parenteral feeding solutions contain adequate levels of PUFAs.

Where did MEDucated get this?

Omega-3 Fatty Acids — Fact Sheet for Health Professionals

NIH Office of Dietary Supplements. Government health-professional reference material imported without MEDucated medical review.

Source section: Groups at Risk of Omega-3 Inadequacy
ODS revision: August 22, 2025
Retrieved: 2026-08-10T22:07:06.488Z
Source fingerprint: 80b4434afaf71303420a09ab193258a2d656c3bdec58a108fe3d14961d1bb750
Cited reference numbers: 5

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Fixture ID: fixture:supplement:omega-3:ods-evidence-preview
Fixture revision: source-revision:nih-ods:omega-3-fatty-acids-health-professional:2026-08-10.80b4434afaf7
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Omega-3 Fatty Acids — Fact Sheet for Health Professionals

NIH Office of Dietary Supplements

Fixture ID: fixture:supplement:omega-3:ods-evidence-preview
Fixture revision: source-revision:nih-ods:omega-3-fatty-acids-health-professional:2026-08-10.80b4434afaf7
Content classification: source backed demonstration
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Evidence classification: government reference
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