Science is dynamic, not static, and as scientific understanding advances scientists sometimes have to modify their positions. Dr. Kidd’s position on EPA and DHA has now changed due to advances in the clinical and basic scientific research. Though the brain carries predominantly DHA and very little EPA, clinical trial results clearly indicate EPA has benefit for mood and probably other higher brain functions. At the basic science level, it has become clear that both EPA and DHA, not DHA alone, are required for the brain to make new nerve cells. Dr. Kidd very closely monitors the research on EPA and… Read more »

Secondly, when we consume EPA, it inhibits the production of AA from DGLA and also competes with AA for uptake into cell membranes and can therefore lower the amount of AA in membranes by literally saturating the cell – in essence, it takes up more of the available ‘space’ and displaces AA. When there is less AA present, there is a reduced capacity for it to produce inflammatory products.

Jatoi, A., Rowland, K., Loprinzi, C. L., Sloan, J. A., Dakhil, S. R., MacDonald, N., Gagnon, B., Novotny, P. J., Mailliard, J. A., Bushey, T. I., Nair, S., and Christensen, B. An eicosapentaenoic acid supplement versus megestrol acetate versus both for patients with cancer-associated wasting: a North Central Cancer Treatment Group and National Cancer Institute of Canada collaborative effort. J.Clin.Oncol. 6-15-2004;22(12):2469-2476. View abstract.
Added inactive ingredients also contribute to product safety. Eight supplements in this study contained ‘natural’ flavors such as citrus-derived additives. One product, Coromega Omega-3, also contained benzoic acid, a popular antibacterial agent linked to carcinogenic risks when combined with vitamin C. Other controversial excipients included the artificial coloring agents FD&C Blue 1 and FD&C Red 40 as well as the whitening agent titanium dioxide.
Pay attention to the quality of fish oil when purchasing it. It is obtained from almost all fishes – fresh water, farm, ocean, deep sea and shallow sea fish. All these fishes can be contaminated with toxic compounds such as mercury, arsenic, lead, forms of calcium, furans, dioxins, PCBs, and methylmercury, and can negatively affect the human body. Therefore, the fish oil used must be pure. Many companies sell ultra refined or distilled fish oil, but you should always check if the standards have been followed and research on the company or the product before adding it to your diet.
Nakamura, N., Hamazaki, T., Ohta, M., Okuda, K., Urakaze, M., Sawazaki, S., Yamazaki, K., Satoh, A., Temaru, R., Ishikura, Y., Takata, M., Kishida, M., and Kobayashi, M. Joint effects of HMG-CoA reductase inhibitors and eicosapentaenoic acids on serum lipid profile and plasma fatty acid concentrations in patients with hyperlipidemia. Int J Clin Lab Res 1999;29(1):22-25. View abstract.
Omega-3 [(n-3)] long-chain PUFA, including EPA and DHA, are dietary fats with an array of health benefits (1). They are incorporated in many parts of the body including cell membranes (2) and play a role in antiinflammatory processes and in the viscosity of cell membranes (3, 4). EPA and DHA are essential for proper fetal development and healthy aging (5). DHA is a key component of all cell membranes and is found in abundance in the brain and retina (6). EPA and DHA are also the precursors of several metabolites that are potent lipid mediators, considered by many investigators to be beneficial in the prevention or treatment of several diseases (7).
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.
Disclaimer: The entire contents of this website are based upon the opinions of Dr. Mercola, unless otherwise noted. Individual articles are based upon the opinions of the respective author, who retains copyright as marked. The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from the research and experience of Dr. Mercola and his community. Dr. Mercola encourages you to make your own health care decisions based upon your research and in partnership with a qualified health care professional. If you are pregnant, nursing, taking medication, or have a medical condition, consult your health care professional before using products based on this content.
First, always remember that it’s the omega-3s that count. When making your purchase, be sure to determine the amount of omega-3s per serving. Many doctors often recommend 1000 to 1200 mg of fish oil because that amount of fish oil contains the total amount of omega-3s the doctor wants you to consume. 1000 mg or 1200 mg of fish oil doesn’t equal 1000 or 1200 mg of omega-3s. A standard 1000 mg fish oil softgel provides around 300 mg of omega-3s (and even less of the important EPA and DHA), and to meet the 500 mg EPA and DHA recommendation, a minimum of two softgels would be necessary. Make sure to read the “Supplement Facts” label to determine the amount of EPA and DHA in a fish oil/omega-3 supplement.

Davidson, M. H., Stein, E. A., Bays, H. E., Maki, K. C., Doyle, R. T., Shalwitz, R. A., Ballantyne, C. M., and Ginsberg, H. N. Efficacy and tolerability of adding prescription omega-3 fatty acids 4 g/d to simvastatin 40 mg/d in hypertriglyceridemic patients: an 8-week, randomized, double-blind, placebo-controlled study. Clin Ther 2007;29(7):1354-1367. View abstract.
While fish for dinner is one way to get EPA and DHA, most people don’t eat the suggested two to three servings of oily fish per week to reap the benefits of omega-3s. What’s more, there are extremely few food sources, aside from fish, that naturally provide EPA and DHA. With all the benefits that can come from fish oil, it’s no surprise that these supplements are increasing in popularity.
Even healthy oils form trans fats when heated. Each oil has a different temperature at which it forms its own trans fats. Generally, when the oil begins to smoke is when trans fats are formed. Did this study consider how and at what temperatures the fish were cooked? Are some of the suppliments heated before being made into capsules? Did it also consider that many types of fish have dangerous levels of mercury?
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.
Consumers of oily fish should be aware of the potential presence of heavy metals and fat-soluble pollutants like PCBs and dioxins, which are known to accumulate up the food chain. After extensive review, researchers from Harvard's School of Public Health in the Journal of the American Medical Association (2006) reported that the benefits of fish intake generally far outweigh the potential risks.
Sala-Vila A, Díaz-López A, Valls-Pedret C, et al.; Prevención con Dieta Mediterránea (PREDIMED) Investigators. Dietary marine ?-3 fatty acids and incident sight-threatening retinopathy in middle-aged and older individuals with type 2 diabetes: Prospective investigation from the PREDIMED trial. JAMA Ophthalmol. 2016;134(10):1142-1149. View abstract.

Finally, in order for AA to be converted into inflammatory products it must be released from phospholipids (part of the cell membrane) using the enzyme phospholipase A2 and then converted by the enzyme cyclooxygenase. EPA utilises both of these enzymes, so if EPA levels are increased in the diet, it attracts enzyme away from AA to EPA – again giving rise to anti-inflammatory products instead of inflammatory ones.

Dyerberg, J., Eskesen, D. C., Andersen, P. W., Astrup, A., Buemann, B., Christensen, J. H., Clausen, P., Rasmussen, B. F., Schmidt, E. B., Tholstrup, T., Toft, E., Toubro, S., and Stender, S. Effects of trans- and n-3 unsaturated fatty acids on cardiovascular risk markers in healthy males. An 8 weeks dietary intervention study. Eur.J.Clin.Nutr. 2004;58(7):1062-1070. View abstract.


You “beat me to the punch.” despite labels, cured meats , aged fats, as well as those heated to a high enough temperature all have trans bonds. Fish that offer high amounts of Omega-3 also often are high in mercury. I was fortunate to have a very good teacher for experimental design. One should be careful to assume that a study actually measures what it claims to and without “confounders” Confounders are parts of the study that complicate the the “logic” of the design. Also, were other fat contents measured or controlled? It would be reasonable to suspect that those with higher levels of Omega-3 could have higher levels of Omega-6, fats in general , High levels of protein, higher levels of testosterone, or lower levels of certain hormones. In addition, statistical studies do not and have never indicated a causal relationship. I have a fear of how much we have begun to rely on statistical correlational studies which are at the end of the day”soft” science.
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.
Most U.S. adults fail to consume adequate amounts of foods rich in EPA and DHA on a regular basis (at least 8 ounces of fatty fish per week is recommended), and probably consume too many omega-6 fats in comparison (soybean oil, canola oil, cottonseed oil, etc.). This omega-3:omega-6 imbalance can have a negative effect on inflammation patterns and may also be implicated as a contributing factor to other processes related to cellular metabolism, hormone signaling, and even weight regulation.

In fact, dietary fat intake has been among the most widely studied dietary risk factors for breast and prostate cancers. Two studies from 2002 explain how omega-3 can protect against breast cancer. BRCA1 (breast cancer gene 1) and BRCA2 (breast cancer gene 2) are two tumor suppressor genes that, when functioning normally, help repair DNA damage, a process that also prevents tumor development.

46. Gajos G, Rostoff P, Undas A, Piwowarska W. Effects of polyunsaturated omega-3 fatty acids on responsiveness to dual antiplatelet therapy in patients undergoing percutaneous coronary intervention: the OMEGA-PCI (OMEGA-3 fatty acids after pci to modify responsiveness to dual antiplatelet therapy) study. J Am Coll Cardiol. 2010;55:1671–8. [PubMed]
Omega-3 fatty acids have been shown to increase platelet responsiveness to subtherapeutic anticoagulation therapies, including aspirin. Recently, it was noted that patient response to aspirin for anticoagulation therapy is widely variable (45), and, thus, the number of patients with a low response to aspirin or aspirin resistance is estimated to range from <1% to 45%, depending on many variables. However, in patients with stable coronary artery disease taking low-dose aspirin, EPA+DHA supplementation has been proven to be as effective as aspirin dose escalation to 325 mg/d for anticoagulation benefits (45). The antiplatelet drug clopidogrel has also been associated with hyporesponsiveness in some patients. This could be attributed to poor patient compliance, differences in genes and platelet reactivity, variability of drug metabolism, and drug interactions. More importantly, in 1 study, patients receiving standard dual antiplatelet therapy (aspirin 75 mg/d and clopidogrel 600-mg loading dose followed by 75 mg/d) were assigned to either EPA+DHA supplementation or placebo. After 1 mo of treatment, the P2Y12 receptor reactivity index (an indicator of clopidogrel resistance) was significantly lower, by 22%, for patients taking EPA+DHA compared with patients taking placebo (P = 0.020) (46).
A Pregnancy Prerequisite: Omega-3 fatty acids directly affect brain development, making it crucial for expectant mothers. Additionally, research indicates they decrease a mother's risk of depression. When the mother doesn't have enough of these essential fatty acids, the baby borrows from her. Some prenatal vitamins now include omega-3s, so be sure to check the label or grab a handful of walnuts each day.
Among the 16 studies comparing the effect of omega-3 PUFA treatment with that of the placebo,33,34,36,47-49,51-53,55-61 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, 16; Hedges g, 0.372; 95% CI, 0.032-0.712; P = .03; eFigure 3 in the Supplement). The meta-analysis of the subgroup focusing on non–placebo-controlled trials also showed a significantly greater association of treatment with reduced anxiety symptoms in patients receiving omega-3 PUFA treatment than in those not receiving it (k, 3; Hedges g, 0.399; 95% CI, 0.154-0.643; P = .001).35,50,54
One meta-analysis concluded that omega−3 fatty acid supplementation demonstrated a modest effect for improving ADHD symptoms.[39] A Cochrane review of PUFA (not necessarily omega−3) supplementation found "there is little evidence that PUFA supplementation provides any benefit for the symptoms of ADHD in children and adolescents",[40] while a different review found "insufficient evidence to draw any conclusion about the use of PUFAs for children with specific learning disorders".[41] Another review concluded that the evidence is inconclusive for the use of omega−3 fatty acids in behavior and non-neurodegenerative neuropsychiatric disorders such as ADHD and depression.[42]
Weimann, A., Bastian, L., Bischoff, W. E., Grotz, M., Hansel, M., Lotz, J., Trautwein, C., Tusch, G., Schlitt, H. J., and Regel, G. Influence of arginine, omega-3 fatty acids and nucleotide-supplemented enteral support on systemic inflammatory response syndrome and multiple organ failure in patients after severe trauma. Nutrition 1998;14(2):165-172. View abstract.
Dry eye. Some clinical research shows that eating more fish oil is linked to a lower risk of getting dry eye syndrome in women. Other research shows that taking a specific fish oil product (PRN Dry Eye Omega Benefits softgels) daily modestly improves symptoms of dry eye such as pain, blurred vision, and sensitivity. Other research using other forms of fish oil products suggests that taking these supplements for 4-12 weeks modest improves some dry eye symptoms. However, the sensation of eye dryness is not always improved. Other research also shows that taking a specific combination products containing fish oil and other ingredients might improve some dry eye symptoms; however, this research is conflicted and poor quality.
Your body also needs omega-6s, another type of fatty acid, to function properly and prevent disease. Unfortunately, these are found in much more abundance than omega-3s in the standard American diet, although your body craves a 1:1 ratio to keep inflammation low. Most modern diets contain a ratio closer to 20:1 or 30:1 omega-6 to omega-3 fatty acids.
The various enzymes (COX and LOX) that make inflammatory eicosanoids can accommodate both AA and EPA, but again due to the greater spatial size of DHA, these enzymes will have difficulty in converting DHA into eicosanoids. This makes DHA a poor substrate for these key inflammatory enzymes. Thus DHA again has little effect on cellular inflammation whereas EPA can have a powerful impact.
High triglycerides. Most research shows that fish oil from supplements and food sources can reduce triglyceride levels. The effects of fish oil appear to be the greatest in people who have very high triglyceride levels. Also the amount of fish oil consumed seems to directly affect how much triglyceride levels are reduced. Some fish oil supplements including Lovaza, Omtryg, and Epanova have been approved by the FDA to lower triglycerides.
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