Healthy cells require a delicate balance of EPA and DHA and the body employs clever mechanisms to support this natural equilibrium. DHA levels are self-regulated through inhibiting the activity of the enzyme delta-6 desaturase – the very enzyme that supports the conversion of EPA into DHA – to ensure levels of DHA do not become too high. It is therefore possible to have too much preformed DHA, if our supplement intake exceeds the body’s needs.
Today the only Food and Drug Administration (FDA)-approved form of dietary omega-3 FA supplement is Lovaza (omega-3-acid ethyl esters; GlaxoSmithKline), which contains 375 mg of DHA and 465 mg of EPA per 1 g capsule. The myriad of dietary supplements of fish oil, including Kosher capsules, vary from comparable content to insignificant amounts, and for the most part can include other fats and cholesterols. In comparison, to achieve approximately 1 g of EPA and DHA in a meal, 12 ounces of canned light tuna, 2 to 3 ounces of sardines, 1.5 to 2.5 ounces of farmed Atlantic salmon, or 20 ounces of farmed catfish must be consumed (Table 1).65 Unfortunately, potentially high levels of harmful pollutants offset this source of omega-3 FA. The FDA action level for unacceptably high mercury content in fish is 1.0 μg/g. The mercury level in most fish is at or below 0.1 μg/g, but tilefish, swordfish, and king mackerel have high levels of mercury. The majority of fish species also contain <100 ng/g of polychlorinated biphenyls, which is below the FDA action level of 2000 ng/g. Dioxins, which do not have FDA action levels, are present in the majority of marine life.66

Saito, Y., Yokoyama, M., Origasa, H., Matsuzaki, M., Matsuzawa, Y., Ishikawa, Y., Oikawa, S., Sasaki, J., Hishida, H., Itakura, H., Kita, T., Kitabatake, A., Nakaya, N., Sakata, T., Shimada, K., and Shirato, K. Effects of EPA on coronary artery disease in hypercholesterolemic patients with multiple risk factors: sub-analysis of primary prevention cases from the Japan EPA Lipid Intervention Study (JELIS). Atherosclerosis 2008;200(1):135-140. View abstract.
Fish oil supplements have been promoted as easy way to protect the heart, ease inflammation, improve mental health, and lengthen life. Such claims are one reason why Americans spend more than $1 billion a year on over-the-counter fish oil. And food companies are adding it to milk, yogurt, cereal, chocolate, cookies, juice, and hundreds of other foods.
Cancer. Research on the effects of fish oil in preventing cancer has produced conflicting results. Some population research suggests that eating fish or having higher blood levels of omega-3 fatty acids from fish oil is linked to a lower risk of different cancers, including oral cancer, pharyngeal cancer, esophageal cancer, colon cancer, rectal cancer, breast cancer, ovarian cancer, and prostate cancer. But other research suggests that eating fish does not reduce the risk of cancer.

Not all forms of fish oil may be equally digestible. Of four studies that compare bioavailability of the glyceryl ester form of fish oil vs. the ethyl ester form, two have concluded the natural glyceryl ester form is better, and the other two studies did not find a significant difference. No studies have shown the ethyl ester form to be superior, although it is cheaper to manufacture.[114][115]


The GISSI-Heart Failure trial was the first blinded, randomized trial to assess the efficacy of fish oil supplements in patients with heart failure.51 The trial enrolled 7046 subjects with heart failure; 60% with New York Heart Association class II symptoms and 40% with a history of MI. The majority of patients were on a standard heart failure regimen, including angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, beta-blockers, and spironolactone, but only 22% were on a statin. At an average of 3.9 years, the coprimary end points of death and death or hospital admission for cardiovascular reasons were reduced by approximately 9% with fish oil supplementation. Sudden cardiac death, a secondary end-point, showed a statistically nonsignificant relative risk reduction of 7% with fish oil. There was also a reduction in 2 other arrhythmia-related secondary end-points: first hospitalization for ventricular arrhythmia and presumed arrhythmic death.
Bianconi, L., Calo, L., Mennuni, M., Santini, L., Morosetti, P., Azzolini, P., Barbato, G., Biscione, F., Romano, P., and Santini, M. n-3 polyunsaturated fatty acids for the prevention of arrhythmia recurrence after electrical cardioversion of chronic persistent atrial fibrillation: a randomized, double-blind, multicentre study. Europace. 2011;13(2):174-181. View abstract.
When it comes to fat, there's one type you don’t want to cut back on: omega-3 fatty acids. Two crucial ones -- EPA and DHA -- are primarily found in certain fish. ALA (alpha-linolenic acid), another omega-3 fatty acid, is found in plant sources such as nuts and seeds. Not only does your body need these fatty acids to function, but also they deliver some big health benefits.
Omega−3 fatty acids, also called ω−3 fatty acids or n−3 fatty acids,[1] are polyunsaturated fatty acids (PUFAs).[2][3] The fatty acids have two ends, the carboxylic acid (-COOH) end, which is considered the beginning of the chain, thus "alpha", and the methyl (-CH3) end, which is considered the "tail" of the chain, thus "omega". One way in which a fatty acid is named is determined by the location of the first double bond, counted from the tail, that is, the omega (ω-) or the n- end. Thus, in omega-3 fatty acids the first double bond is between the third and fourth carbon atoms from the tail end. However, the standard (IUPAC) chemical nomenclature system starts from the carboxyl end.
Omega-3 fatty acids get a fair amount of time in the press and a great deal of respect at this point. But do you know what omega-3s are? What omega-3 benefits could convince you to add more oily fish (or maybe a supplement) to your diet? Are omega-3 foods really that big of a deal when it comes to eating a nutrient-dense diet? Could you be deficient in these fatty acids?

There have been conflicting results reported about EPA and DHA and their use with regard to major coronary events and their use after myocardial infarction. EPA+DHA has been associated with a reduced risk of recurrent coronary artery events and sudden cardiac death after an acute myocardial infarction (RR, 0.47; 95% CI: 0.219–0.995) and a reduction in heart failure events (adjusted HR: 0.92; 99% CI: 0.849–0.999) (34–36). A study using EPA supplementation in combination with a statin, compared with statin therapy alone, found that, after 5 y, the patients in the EPA group (n = 262) who had a history of coronary artery disease had a 19% relative reduction in major coronary events (P = 0.011). However, in patients with no history of coronary artery disease (n = 104), major coronary events were reduced by 18%, but this finding was not significant (37). This Japanese population already has a high relative intake of fish compared with other nations, and, thus, these data suggest that supplementation has cardiovascular benefits in those who already have sufficient baseline EPA+DHA levels. Another study compared patients with impaired glucose metabolism (n = 4565) with normoglycemic patients (n = 14,080). Impaired glucose metabolism patients had a significantly higher coronary artery disease HR (1.71 in the non-EPA group and 1.63 in the EPA group). The primary endpoint was any major coronary event including sudden cardiac death, myocardial infarction, and other nonfatal events. Treatment of impaired glucose metabolism patients with EPA showed a significantly lower major coronary event HR of 0.78 compared with the non–EPA-treated impaired glucose metabolism patients (95% CI: 0.60–0.998; P = 0.048), which demonstrates that EPA significantly suppresses major coronary events (38). When looking at the use of EPA+DHA and cardiovascular events after myocardial infarction, of 4837 patients, a major cardiovascular event occurred in 671 patients (13.9%) (39). A post hoc analysis of the data from these diabetic patients showed that rates of fatal coronary heart disease and arrhythmia-related events were lower among patients in the EPA+DHA group than among the placebo group (HR for fatal coronary heart disease: 0.51; 95% CI: 0.27–0.97; HR for arrhythmia-related events: 0.51; 95% CI: 0.24–1.11, not statistically significant) (39). Another study found that there was no significant difference in sudden cardiac death or total mortality between an EPA+DHA supplementation group and a control group in those patients treated after myocardial infarction (40). Although these last 2 studies appear to be negative in their results, it is possible that the more aggressive treatment with medications in these more recent studies could attribute to this.
Jump up ^ Burch, Ernest S. (2006). Social Life in Northwest Alaska: The Structure of Iñupiaq Eskimo Nations. University of Alaska Press. p. 278. ISBN 9781889963921. Retrieved 2014-10-23. Oil was also used externally as an ointment to heal cold sores, cuts, insect bites, frostbite, rashes - in short, skin problems of all kinds. Duck or goose body-cavity fat was apparently as useful as seal or fish oil in dealing with skin problems.
To evaluate the potential placebo effect, we made further subgrouping analyses. In the subgroups of studies using placebo controls, the omega-3 PUFAs still revealed a consistent positive anxiolytic association with anxiety symptoms. These phenomena meant that the anxiolytic effect of omega-3 PUFAs is probably not entirely owing to the placebo effect.
Omega-3s are important components of the membranes that surround each cell in your body. DHA levels are especially high in retina (eye), brain, and sperm cells. Omega-3s also provide calories to give your body energy and have many functions in your heart, blood vessels, lungs, immune system, and endocrine system (the network of hormone-producing glands).
Secondary prevention fish oil studies demonstrate a significant reduction in MI. But unfortunately, both the observational and randomized trials were conducted in an era before the widespread use of HMG-CoA reductase inhibitors, and therefore, the incremental benefit is still unknown. Nevertheless, in patients receiving antiplatelet and anticoagulant therapy in addition to fish oil supplementation (even at doses as high as 4 g per day), no serious adverse complications have been reported.
Although GOED has used diligent care to ensure that the information provided on this website is accurate and up to date, we make no representation or warranty of the accuracy, reliability or completeness of this information. The website is intended to educate and inform readers about omega-3 fatty acids and is not meant to constitute or provide medical advice, diagnosis or treatment and is distributed without warranty of any kind, either expressly or implied. In no event shall GOED be liable for any damages arising from the reader’s reliance upon, or use of, these materials. The reader shall be solely responsible for any interpretation or use of material contained herein. The content of this document is subject to change without further notice.

Fish or seafood allergy: Some people who are allergic to seafood such as fish might also be allergic to fish oil supplements. There is no reliable information showing how likely people with seafood allergy are to have an allergic reaction to fish oil. Until more is known, advise patients allergic to seafood to avoid or use fish oil supplements cautiously.


In comparison, the omega-3s found in krill appear to be more rapidly incorporated into red blood cell phospholipids.7 This is important, because not only do scientists view the uptake of essential fatty acids in red blood cells as a biomarker for uptake into the brain,8 but additional research suggests that when omega-3 fatty acids such as DHA are bound to phospholipids as they are with krill, it increases their uptake to the brain.9 This is further supported by human clinical research, which suggests ingestion of phospholipid-bound EPA and DHA increase cognitive function scores to a greater degree compared with scores obtained when the fatty acids in the ingested oil were provided in the triglycerides storage form.10
Dioxins and PCBs may be carcinogenic at low levels of exposure over time. These substances are identified and measured in one of two categories, dioxin-like PCBs and total PCBs. While the U.S. FDA has not set a limit for PCBs in supplements, the Global Organization for EPA and DHA (GOED) has established a guideline allowing for no more than 3 picograms of dioxin-like PCBs per gram of fish oil. In 2012, samples from 35 fish oil supplements were tested for PCBs. Trace amounts of PCBs were found in all samples, and two samples exceeded the GOED‘s limit.[52] Although trace amounts of PCBs contribute to overall PCB exposure, Consumerlab.com claims the amounts reported by tests it ordered on fish oil supplements are far below those found in a single typical serving of fish.[52]

The Japanese notably have the lowest levels of coronary heart disease mortality and atherosclerosis among developed nations — a phenomena that has been largely subscribed to diet. However, even within Japan, a 10-year study of over 41,000 people found that higher intakes of omega-3s were associated with lower risks of nonfatal coronary events (8). A more recent study also found that Japanese with higher omega-3 index levels (10%) had a lower risk of fatal coronary heart disease than those with a lower omega-3 index levels (8%) (9). The study begs the question of whether maybe even the Japanese have room to improve their omega-3 intake and whether 8% should be considered the lower limit of a desirable range.

The University of East Anglia (UEA) is a UK Top 15 university. Known for its world-leading research and outstanding student experience, it was awarded Gold in the Teaching Excellence Framework and  is a leading member of Norwich Research Park, one of Europe’s biggest concentrations of researchers in the fields of environment, health and plant science. www.uea.ac.uk.
36. Marchioli R, Barzi F, Bomba E, Chieffo C, Di Gregorio D, Di Mascio R, Franzosi MG, Geraci E, Levantesi G, Maggioni AP, et al. Early protection against sudden death by n-3 polyunsaturated fatty acids after myocardial infarction: time-course analysis of the results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-Prevenzione. Circulation. 2002;105:1897–903. [PubMed]
Fish oil’s most potent effect on atherosclerosis may be related to its potential to alter plaque inflammation, thereby stabilizing vulnerable plaques. In recent years there has been a growing body of evidence that is shifting the paradigm of how inflammation is contained and dissipated.4 In this new model, inflammation resolution is an active process mediated by lipid-derived compounds. Newly discovered families of chemical mediators, resolvins, and protectins5,6 are directly involved in blocking neutrophil migration, infiltration, and recruitment, as well as in blocking T-cell migration and promoting T-cell apoptosis.7–12 In addition, protectins can reduce tumor necrosis factor and interferon secretion.13 Interestingly, both protectins and resolvins are strictly derived from omega-3 FA. EPA is the substrate of the resolvins family and DHA can be converted to both resolvins and protectins.7 It may be that the effects of fish oil on inflammatory mediators underlie the positive findings demonstrated in several trials assessing fish oil and plaque stability.14–16
Secondary prevention fish oil studies demonstrate a significant reduction in MI. But unfortunately, both the observational and randomized trials were conducted in an era before the widespread use of HMG-CoA reductase inhibitors, and therefore, the incremental benefit is still unknown. Nevertheless, in patients receiving antiplatelet and anticoagulant therapy in addition to fish oil supplementation (even at doses as high as 4 g per day), no serious adverse complications have been reported.
Thank you for your kind comment. As pointed out above, the main limitation of our meta-analysis is the heterogeneity, which we address several times in our main manuscript. We included studies with several different situations and participants with different underlying diseases, which would also result in wide heterogeneity in our meta-analysis. Based upon our post-hoc analysis, there was some common characteristics among the six trials with nominally significant results, including specific clinical diagnoses (5/6) and, placebo-control (4/6), which had also previously been addressed in our subgroup meta-analysis. Therefore, we suggested future placebo-controlled trials investigating the treatment effect of omega-3 in participants with specific clinical diagnoses should be warranted. In addition, improving underlying specific clinical diagnoses (5/6), good quality (placebo-control (4/6), low drop-out rate (zero in Exp/control groups: 4/6)), and long treatment duration (>= 12 weeks: 4/6) are all good indicators of high quality.
It is great for improving the condition of the dry skin by making it look shiny and vibrant. It is useful in treating various skin problems such as eczema, psoriasis, itching, skin redness, skin lesions, and rashes. In terms of psoriasis, the EPA present in fish oil restricts the growth of pro-inflammatory agents by producing arachidonic acid. Therefore, fish oil can also be applied topically to get relief from psoriasis.
The question is whether the observed cardiovascular benefits often found among fish eaters is due solely to the oils in fish or to some other characteristics of seafood or to still other factors common to those who eat lots of fish, like eating less meat or pursuing a healthier lifestyle over all. Whatever the answer, it does not seem to be fish oil supplements.
It is also believed that women who do not have a sufficient intake of EPA and DHA in their diet suffer from depression after childbirth, as there is a transfer of some amount of brain mass from the mother to the child in the last stages of pregnancy. Thus, it is very beneficial to consume fish oil either by eating fish or taking fish oil supplements, tablets, capsules, or pills during pregnancy for the overall development of the child and the well-being of the mother. However, it should be noted that fish oil obtained from the liver of the fish, example – cod liver oil, should not be consumed during pregnancy as cod liver oil is high in retinol and vitamin A, which are usually known to cause birth defects.
The GISSI-Prevenzione trial40 showed similar findings. In this open-label trial, 11,324 post-MI patients were followed for 3.5 years after randomization to either 1 g/d of omega-3 FA, vitamin E, both, or none. In the 2836 patients assigned to only omega-3 FA, the primary end point of death, nonfatal MI or stroke, was reduced by 10%. This decreased risk occurred despite a minimal triglyceride-lowering effect because of the relatively low dose of omega-3 FA. Of note, the GISSI-Prevenzione trial was done prior to the pervasive use of lipid-lowering agents. Only about 40% of patients were on any form of lipid-lowering therapy.
“The review provides good evidence that taking long-chain omega 3 (fish oil, EPA or DHA) supplements does not benefit heart health or reduce our risk of stroke or death from any cause.  The most trustworthy studies consistently showed little or no effect of long-chain omega 3 fats on cardiovascular health. On the other hand, while oily fish is a healthy food, it is unclear from the small number of trials whether eating more oily fish is protective of our hearts. 

A 2008 meta-study by the Canadian Medical Association Journal found fish oil supplementation did not demonstrate any preventative benefit to cardiac patients with ventricular arrhythmias.[36] A 2012 meta-analysis published in the Journal of the American Medical Association, covering 20 studies and 68,680 patients, found that Omega-3 Fatty Acid supplementation did not reduce the chance of death, cardiac death, heart attack or stroke.[37]
The DART study, published in 1989, was the first randomized trial to show the efficacy of fish oil on CAD.37 In the trial, 2033 post-MI patients were randomized to receive 3 types of diets: a diet that was either high in cereal fiber, polyunsaturated fat, or fish oil. The fish oil group consumed 200 to 400 g/wk of fatty fish (2 portions of fish per week) or 0.5 g/d of Maxepa fish oil supplement. At 2 years, the primary end point of all-cause mortality was reduced by 29% in the fish oil group, whereas no improvement was seen in the other dietary advice groups.
After just seven days, those supplementing with krill had their CRP levels reduced by 19.3%, while in the placebo group, CRP levels rose by 15.7%. Even more impressive, the krill benefit was long-lasting. The krill group’s CRP levels continued to fall by 29.7% at 14 days, and 30.9% at 30 days. More importantly from the patients’ points of view, the krill oil supplement reduced pain scores by 28.9%, reduced stiffness by 20.3%, and reduced functional impairment by 22.8%.

Research conducted by Professor Peter Howe at the University of South Australia has shown that fish oil improves the efficacy of exercise in attempts to reduce weight. Volunteers who were given fish oil in their diet showed greater weight loss as compared to those who did not regularly consume it. Fish oil contains omega-3 fatty acids, which help to promote the weight loss, so a combination of physical workout and intake of this oil helps in reducing body fat significantly faster.
Omega-3 fatty acids are found primarily in fish oil and certain marine algae. Because depression appears less common in nations where people eat large amounts of fish, scientists have investigated whether fish oils may prevent and/or treat depression and other mood disorders. Two omega-3 fatty acids — eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) — are thought to have the most potential to benefit people with mood disorders.
We hypothesized that omega-3 PUFAs might have anxiolytic effects in patients with significant anxiety- and fear-related symptoms. However, there have been no systematic reviews of this topic to date. Thus, we examined the anxiolytic effects of omega-3 PUFAs in participants with elevated anxiety symptoms in the results of clinical trials to determine the overall efficacy of omega-3 PUFAs for anxiety symptoms irrespective of diagnosis.
As with other supplements, when it comes to quality, you get what you pay for. Life Time sources its omega-3 fish oil (both capsules and liquid) from sustainable fisheries off the coast of Chile. We only use oils from small, cold-water anchovy, sardine, and mackerel. It’s molecularly distilled to be sure it’s free of mercury, PCBs, and heavy metals. If your fish oil brand doesn’t name the species of fish it’s sourced from, or it lists larger, predatory species, the quality and purity of the oil could be less than optimal.
Luo, J Rizkalla SW Vidal H Oppert JM Colas C Boussairi A Guerre-Millo M Chapuis AS Chevalier A Durand G Slama G. Moderate intake of n-3 fatty acids for 2 months has no detrimental effect on glucose metabolism and could ameliorate the lipid profile in type 2 diabetic men. Results of a controlled study. Diabetes Care. 1998;21(5):717-724. View abstract.
Rondanelli, M., Giacosa, A., Opizzi, A., Pelucchi, C., La, Vecchia C., Montorfano, G., Negroni, M., Berra, B., Politi, P., and Rizzo, A. M. Effect of omega-3 fatty acids supplementation on depressive symptoms and on health-related quality of life in the treatment of elderly women with depression: a double-blind, placebo-controlled, randomized clinical trial. J.Am.Coll.Nutr. 2010;29(1):55-64. View abstract.
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