Your concerns are very valid. The quality of commercially available omega-3 preparations can vary greatly. In our clinical trials we use preparations made by reputable manufacturers with high standards. We also have the preparations analyzed by 2 independent labs to confirm omega-3 content, impurities, and degree of oxidation, prior to initiating the study. While omega-3 fatty acids–like most nutrients–are ideally obtained through dietary practice, because many people may not enjoy omega-3 containing foods, supplements may be a good option for these individuals. Anyone who is interested in using an omega-3 preparation for treating a psychiatric condition should do so preferably under the supervision of a psychiatrist.
Ozaydin, M., Erdogan, D., Tayyar, S., Uysal, B. A., Dogan, A., Icli, A., Ozkan, E., Varol, E., Turker, Y., and Arslan, A. N-3 polyunsaturated fatty acids administration does not reduce the recurrence rates of atrial fibrillation and inflammation after electrical cardioversion: a prospective randomized study. Anadolu.Kardiyol.Derg. 2011;11(4):305-309. View abstract.
The human body does not produce significant amounts of EPA or DHA on its own, so you must get these important nutrients from the foods you eat and the supplements you consume. If you’re looking to get the heart health benefits of omega-3s, go straight to the source of EPA and DHA. EPA and DHA are naturally found in marine sources, including fatty fish – salmon, tuna, mackerel, herring – shellfish, and marine algae.
What's more, ALA is just a precursor to EPA and DHA. You need certain enzymes to elongate and desaturate ALA so it can become long-chained omega-3s. Unfortunately, this does not work in some people, particularly those who are deficient in certain vitamins and minerals, leading to very low conversion rates – only 1 percent of ALA is converted to EPA/DHA. In some, the conversion can even dip as low as 0.1 to 0.5 percent!
The omega-3 index may also be helpful for assessing health risks beyond cardiovascular disease. Studies are currently investigating the relationship between omega-3 index levels and mental health issues, like depression (15, 16, 17), cognitive functioning (18, 19), body weight (20), as well as eye health issues, like macular degeneration (21), to name just a few.
An 18-month study was published in 2014 that evaluated how borage seed oil — rich in GLA — and fish oil rich fared against each other in treating patients with rheumatoid arthritis. It was discovered that all three groups (one taking fish oil, one taking borage oil and one taking a combination of the two) “exhibited significant reductions” in disease activity, and no therapy outperformed the others. For all three, “meaningful clinical responses” were the same after nine months. (11)
Hamazaki, K., Syafruddin, D., Tunru, I. S., Azwir, M. F., Asih, P. B., Sawazaki, S., and Hamazaki, T. The effects of docosahexaenoic acid-rich fish oil on behavior, school attendance rate and malaria infection in school children--a double-blind, randomized, placebo-controlled trial in Lampung, Indonesia. Asia Pac.J Clin Nutr 2008;17(2):258-263. View abstract.
There are numerous omega-3 sources with varying proportions of EPA and DHA, and the balance of EPA and DHA in a supplement influences the actions of these fats in the body. For more information about the different types of omega-3 sources and which are most suited for your individual needs, read our page on the different types of omega-3 supplements
While fish oil has plenty of beneficial qualities, there is a lot of hype around its possible applications, and not all of them are accurate, so be wary when reading literature on this useful oil. Fish oil manufacturers have attempted to market it as a remedy for almost anything. We suggest that readers educate themselves fully before making an informed decision, rather than getting affected by both negative and positive propaganda about the beneficial applications of fish oil.
“This idea has since been pretty discredited; we really don’t know if the Eskimos got heart disease or not,” said Malden C. Nesheim, emeritus professor of nutrition at Cornell University, who chaired an Institute of Medicine committee assessing the risks and benefits of seafood in the early 2000s. “I’ve been an omega-3 skeptic since doing this study.”
A healthy balance of dietary omega 6 and omega 3 fatty acids is a prerequisite for normal immune function, cognitive health, and cardiovascular health. Among other factors, sufficient dietary levels of EPA, DHA or other omega 3 fatty acids are also important in the regulation of normal blood lipoprotein and healthy cholesterol metabolism. Fish oil supplements can also lower elevated triglyceride levels, improving cardiovascular health and reducing the risk of heart disease.†

Fish oil supplements came under scrutiny in 2006, when the Food Standards Agency in the UK and the Food Safety Authority of Ireland reported PCB levels that exceeded the European maximum limits in several fish oil brands,[60][61] which required temporary withdrawal of these brands. To address the concern over contaminated fish oil supplements, the International Fish Oil Standards (IFOS) Program, a third-party testing and accreditation program for fish oil products, was created by Nutrasource Diagnostics Inc. in Guelph, Ontario, Canada.[62]
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.
Krauss-Etschmann et al. (26) Double-blind, placebo-controlled, randomized 311 DHA+EPA daily with either fish oil with DHA (0.5 g) and EPA (0.15 g) or with methyltetrahydrofolic acid (400 μg), both, or placebo, from gestation week 22 Fish-oil supplementation was associated with decreased levels of maternal inflammatory/TH1 cytokines and a decrease of fetal Th2-related cytokines
Henriksen, C., Haugholt, K., Lindgren, M., Aurvag, A. K., Ronnestad, A., Gronn, M., Solberg, R., Moen, A., Nakstad, B., Berge, R. K., Smith, L., Iversen, P. O., and Drevon, C. A. Improved cognitive development among preterm infants attributable to early supplementation of human milk with docosahexaenoic acid and arachidonic acid. Pediatrics 2008;121(6):1137-1145. View abstract.
In 1964 it was discovered that enzymes found in sheep tissues convert omega−6 arachidonic acid into the inflammatory agent called prostaglandin E2[71] which both causes the sensation of pain and expedites healing and immune response in traumatized and infected tissues.[72] By 1979 more of what are now known as eicosanoids were discovered: thromboxanes, prostacyclins, and the leukotrienes.[72] The eicosanoids, which have important biological functions, typically have a short active lifetime in the body, starting with synthesis from fatty acids and ending with metabolism by enzymes. If the rate of synthesis exceeds the rate of metabolism, the excess eicosanoids may, however, have deleterious effects.[72] Researchers found that certain omega−3 fatty acids are also converted into eicosanoids, but at a much slower rate. Eicosanoids made from omega−3 fatty acids are often referred to as anti-inflammatory, but in fact they are just less inflammatory than those made from omega−6 fats. If both omega−3 and omega−6 fatty acids are present, they will "compete" to be transformed,[72] so the ratio of long-chain omega−3:omega−6 fatty acids directly affects the type of eicosanoids that are produced.[72]
If we want to deliver the benefits associated with EPA therapeutically, it is essential to optimise digestion and uptake. If we take EPA and DHA in their natural 1.5:1 ratio, it’s an uphill struggle for EPA because we know that DHA is more effectively absorbed and assimilated into cells. Delivering the benefits of EPA (for example, for cognitive function, mood and depression, inflammation regulation, heart health, skin health and so on), requires doses of EPA in excess of DHA, which determines the type of benefits obtained and the degree of the beneficial outcomes. The higher the ratio of EPA to DHA (meaning higher doses of EPA in relation to DHA), the more likely that EPA will be digested and absorbed, ready to meet the body’s high demands for this important nutrient.
Belalcazar, L. M., Reboussin, D. M., Haffner, S. M., Reeves, R. S., Schwenke, D. C., Hoogeveen, R. C., Pi-Sunyer, F. X., and Ballantyne, C. M. Marine omega-3 fatty acid intake: associations with cardiometabolic risk and response to weight loss intervention in the Look AHEAD (Action for Health in Diabetes) study. Diabetes Care 2010;33(1):197-199. View abstract.
To exclude the possible confounding effects of clinical variables on the Hedges g, metaregression analysis was conducted with an unrestricted maximum likelihood random-effects model of single variables when there were more than 10 data sets available. Specifically, the clinical variables of interest included mean age, female proportion, sample size, mean body mass index, daily omega-3 PUFA dosage, EPA to DHA ratio, treatment duration, dropout rate, and others. In addition, a subgroup meta-analysis was conducted to investigate potential sources of heterogeneity, specifically, a further subgroup meta-analysis focused on those trials that were placebo controlled or non–placebo controlled. To more clearly uncover the differences in the meta-analysis results among the recruited studies, a further subgroup meta-analysis was performed according to the presence of a specific clinical diagnosis or no specific clinical condition, mean omega-3 PUFA daily dosage, and mean age. In addition, in a previous study, the EPA percentage (ie, ≥60%) in the PUFA regimens had different effects on depression treatment.9 Therefore, we also arranged the subgroup meta-analysis based on the EPA percentage. Furthermore, we arranged subgroup meta-analysis procedures only when there were at least 3 data sets included.45 To investigate the potentially different estimated effect sizes between subgroups, we performed an interaction test and calculated the corresponding P values.46

^ Jump up to: a b MacLean CH, Newberry SJ, Mojica WA, Khanna P, Issa AM, Suttorp MJ, Lim YW, Traina SB, Hilton L, Garland R, Morton SC (2006-01-25). "Effects of omega−3 fatty acids on cancer risk: a systematic review". JAMA: The Journal of the American Medical Association. 295 (4): 403–15. doi:10.1001/jama.295.4.403. PMID 16434631. Retrieved 2006-07-07.
Nielsen, G. L., Faarvang, K. L., Thomsen, B. S., Teglbjaerg, K. L., Jensen, L. T., Hansen, T. M., Lervang, H. H., Schmidt, E. B., Dyerberg, J., and Ernst, E. The effects of dietary supplementation with n-3 polyunsaturated fatty acids in patients with rheumatoid arthritis: a randomized, double blind trial. Eur J Clin Invest 1992;22(10):687-691. View abstract.
Like I mentioned earlier, there are no official guidelines for the proper amount of omega-3s you should consume each day. However, most organization agree that at least 2 servings of a 3.5 ounce serving of fish (preferably oily) each week is a good start. That equals about 500 milligrams of EPA/DHA each day. For treating disease, up to 4,000 milligrams per day is recommended by various studies, although values do vary. (96) It’s why a pescatarian diet can have such health protective effects.
Nine studies with 10 data sets used omega-3 PUFA dosages of less than 2000 mg/d.35,47,48,51,53,55,56,60,61 The main results revealed that there was no significant difference in the association of treatment with reduced anxiety symptoms between patients receiving omega-3 PUFA treatment and those not receiving it (k, 9; Hedges g, 0.457; 95% CI, –0.077 to 0.991; P = .09) (Figure 3B). Ten studies with 10 data sets used omega-3 PUFA dosages of at least 2000 mg/d.33,34,36,49,50,52,54,55,57-59 The main results revealed a significantly greater association of treatment with reduced anxiety symptoms in patients receiving omega-3 PUFA treatment than in those not receiving it (k, 11; Hedges g, 0.213; 95% CI, 0.031-0.395; P = .02) (Figure 3B). Furthermore, there was no significantly different estimated effect sizes between these 2 subgroups by the interaction test (P = .40).
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.
There have been numerous clinical trials looking mainly at death, stroke, and cardiac outcomes related to omega 3 consumption, either in food or in supplements. Now the Cochrane Library has published the largest systematic review of these studies to date. Unfortunately, the review shows little benefit from consuming omega 3 fatty acid. This is a fairly extensive review with good statistical power:
Is krill oil better than fish oil for omega-3? Krill oil and fish oil are popular dietary supplements containing omega-3. Krill oil comes from a small crustacean while fish oil comes from oily fish, such as salmon. Both are shown to increase blood levels of omega-3 and have benefits for health. Learn more about the differences between krill oil and fish oil here. Read now
Preventing re-blockage of blood vessels after angioplasty, a procedure to open a closed blood vessel. Research suggests that fish oil decreases the rate of blood vessel re-blockage by up to 45% when given for at least 3 weeks before an angioplasty and continued for one month thereafter. But, when given for 2 weeks or less before angioplasty, it doesn't seem to have any effect.