Not surprising, there are some areas in which both EPA and DHA appear to be equally beneficial. As an example, both are equally effective in reducing triglyceride levels (10). This is probably due to the relatively equivalent activation of the gene transcription factor (PPAR alpha) that causes the enhanced synthesis of the enzymes that oxidize fats in lipoprotein particles. There is also apparently equal activation of the anti-inflammatory gene transcription factor PPAR-gamma (11). Both seem to be equally effective in making powerful anti-inflammatory eicosanoids known as resolvins (12). Finally, although both have no effect on total cholesterol levels, DHA can increase the size of LDL particle to a greater extent than can EPA (10).
Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.
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]
Findings  In this systematic review and meta-analysis of 19 clinical trials including 2240 participants from 11 countries, improvement in anxiety symptoms was associated with omega-3 polyunsaturated fatty acid treatment compared with controls in both placebo-controlled and non–placebo-controlled trials. The anxiolytic effects of omega-3 polyunsaturated fatty acids were also stronger in participants with clinical conditions than in subclinical populations.
Keep in mind that APA found in plant-based foods takes a lot of energy for your body to convert to EPA and DHA. I understand that many people following a vegan diet struggle with the concept of fish oil or eating fish, but animal products contain the necessary omega-3 fatty acids to allow your body to absorb and synthesize what you take in. However, there are plant-based options — you’ll just need more APA because of the way your body processes the medium-chain fatty acid.
The number, location, and orientation of the double bonds determine the health effects of fatty acids on the body. One aspect of this is their effect on triglycerides and LDL and HDL types of cholesterol, which in turn affect how much cholesterol gets deposited on the inside of blood vessels. There are also subtypes of LDL and HDL which are also likely important to their health effects.
It is believed that regular consumption of fish oil aids in boosting your immune system, thereby enabling you to resist the occurrence of common diseases like colds, cough, and the flu. Omega-3 fatty acids present in fish oil bolster the immune system by affecting the activity and amount of cytokines and eicosanoids present in our body. Researchers have also studied the effect of a fish meal and fish oil on the immune system of pigs and found that fish oil aided in the growth of the animals. Similar research conducted on mice at Taichung Veterans General Hospital, Taiwan, also gave positive results.
The most widely available dietary source of EPA and DHA is oily fish, such as salmon, herring, mackerel, anchovies, menhaden, and sardines. Oils from these fish have a profile of around seven times as much omega−3 as omega−6. Other oily fish, such as tuna, also contain n-3 in somewhat lesser amounts. 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) [110] reported that the benefits of fish intake generally far outweigh the potential risks. Although fish are a dietary source of omega−3 fatty acids, fish do not synthesize them; they obtain them from the algae (microalgae in particular) or plankton in their diets.[111] In the case of farmed fish, omega-3 fatty acids is provided by fish oil; In 2009, 81% of the global fish oil production is used by aquaculture.[112]
Arsenault, L. N., Matthan, N., Scott, T. M., Dallal, G., Lichtenstein, A. H., Folstein, M. F., Rosenberg, I., and Tucker, K. L. Validity of estimated dietary eicosapentaenoic acid and docosahexaenoic acid intakes determined by interviewer-administered food frequency questionnaire among older adults with mild-to-moderate cognitive impairment or dementia. Am J Epidemiol 7-1-2009;170(1):95-103. View abstract.
Sorgi, P. J., Hallowell, E. M., Hutchins, H. L. & Sears, B. (2007, January 17). Effects of an open-label pilot study with high-dose EPA/DHA concentrates on plasma phospholipids and behavior in children with attention deficit hyperactivity disorder. Nutrition Journal 6(16). Retrieved from http://nutritionj.biomedcentral.com/articles/10.1186/1475-2891-6-16
EPA, which is eicosapentaenoic acid, and DHA, which is docosahexaenoic acid, are two types of omega-3 fatty acids that are most commonly found in seafood. These polyunsaturated fats are known to have preventative health benefits and have been studied for their role in treating certain chronic conditions. In addition to dietary sources, certain supplements such as fish oil, are also rich in EPA and DHA.

Dornstauder, B., Suh, M., Kuny, S., Gaillard, F., MacDonald, I., Michael T. Clandinin, M. T., & Sauvé, Y. (2012, June). Dietary docosahexaenoic acid supplementation prevents age-related functional losses and A2E accumulation in the retina. Investigative Ophthalmology and Visual Science. Retrieved from http://iovs.arvojournals.org/article.aspx?articleid=2188773
Fish oil is very beneficial for pregnant women because the DHA present in it helps in the development of the eyes and brain of the baby. It also helps to avoid premature births, low birth weight, and miscarriages. Research conducted in Denmark, which involved 8,729 pregnant women, concluded that a diet with low amounts of fish resulted in a higher risk of premature or preterm babies.
Thanks to fatdog11 for that informative post about PCB’s in fish-oil supplements. Are these same toxicity levels found in fish themselves, or possibly are these levels so high only in highly concentrated fish-oil products? Also, can fatdog11 please inform us more about algae-derived omega-3. What are the DHA and EPA levels in these capsules? What is the cost, and where can they be purchased?
Under these conditions, it may make sense to try fish oil even at higher doses than what I recommended. There is some evidence that krill oil will get the omega-3 fatty acids better into the brain in the psychiatric conditions that I listed. And there is some evidence that EPA-rich fish oils are better than DHA-rich fish oils for some of those psychiatric conditions as well. So there’s room to play around with the different possibilities if those things apply to you. But for the average case, limit the fish oil to 250 milligrams of EPA and DHA combined when you take it, but in all cases, go for food first, and go for fish oil only after you have exhausted those possibilities.
Sekikawa, A., Curb, D., Ueshima, H., El-Saed, A., Kadowaki, T., Abbott, R. D., ... Kuller, L. H. (2008 August 5). Marine-derived n-3 fatty acids and atherosclerosis in Japanese, Japanese Americans, and Whites: a cross-sectional study. Journal of the American College of Cardiology 52(6), 417–424. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2736602/
People with metabolic syndrome (the combination of central obesity, high blood pressure, disturbed lipid profile, and impaired glucose tolerance) are at increased risk of death from cardiovascular disease, diabetes, cancer, and other apparently “age-related” disorders. Because metabolic syndrome is closely associated with chronic low-grade inflammation, the powerful anti-inflammatory effects of omega-3 fats are especially important as a means of slowing or stopping the progression of this deadly disorder.
In total, 19 articles with 19 data sets revealed the main results of the meta-analysis, namely that there was a significantly better association of treatment with reduced anxiety symptoms in patients receiving omega-3 PUFA treatment than in those not receiving it (k, 19; Hedges g, 0.374; 95% CI, 0.081-0.666; P = .01; Figure 2), with significant heterogeneity (Cochran Q, 178.820; df, 18; I2, 89.934%; P < .001) but no significant publication bias via Egger regression (t, 1.736; df, 17; P = .10) or inspection of the funnel plot (eFigure 2 in the Supplement). According to the trim-and-fill test, there was no need for adjustment for publication bias. The meta-analysis results remained significant after removal of any one of the included studies, which indicated that the significant results are not owing to any single study.
In general, most health organizations agree 250–500 milligrams of EPA and DHA combined each day is a reasonable amount to support healthy individuals. However, people with heart problems (or those with a high risk of heart disease), depression, anxiety and cancer (and possibly more conditions) may benefit from higher doses — up to 4,000 milligrams per day for some heart-related conditions. (5)
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.

Stiefel, P., Ruiz-Gutierrez, V., Gajon, E., Acosta, D., Garcia-Donas, M. A., Madrazo, J., Villar, J., and Carneado, J. Sodium transport kinetics, cell membrane lipid composition, neural conduction and metabolic control in type 1 diabetic patients. Changes after a low-dose n-3 fatty acid dietary intervention. Ann Nutr Metab 1999;43(2):113-120. View abstract.
Under these conditions, it may make sense to try fish oil even at higher doses than what I recommended. There is some evidence that krill oil will get the omega-3 fatty acids better into the brain in the psychiatric conditions that I listed. And there is some evidence that EPA-rich fish oils are better than DHA-rich fish oils for some of those psychiatric conditions as well. So there’s room to play around with the different possibilities if those things apply to you. But for the average case, limit the fish oil to 250 milligrams of EPA and DHA combined when you take it, but in all cases, go for food first, and go for fish oil only after you have exhausted those possibilities.
People with metabolic syndrome (the combination of central obesity, high blood pressure, disturbed lipid profile, and impaired glucose tolerance) are at increased risk of death from cardiovascular disease, diabetes, cancer, and other apparently “age-related” disorders. Because metabolic syndrome is closely associated with chronic low-grade inflammation, the powerful anti-inflammatory effects of omega-3 fats are especially important as a means of slowing or stopping the progression of this deadly disorder.
Animal studies show potent reduction of liver fat stores, glucose levels, and cholesterol levels in mice supplemented with krill oil while being fed a high fat diet.64,65 While many of these effects are seen with fish oil as well, studies show that krill oil, with its unique phospholipid structure, had the added benefit of increasing fat-burning in mitochondria while reducing new glucose production in the liver.66,67 As with so many other complex disease processes, utilizing multiple pathways to reduce disease is a highly effective strategy.67
Fish oil is FDA approved to lower triglycerides levels, but it is also used for many other conditions. It is most often used for conditions related to the heart and blood system. Some people use fish oil to lower blood pressure, triglycerides and cholesterol levels. Fish oil has also been used for preventing heart disease or stroke, as well as for clogged arteries, chest pain, irregular heartbeat, bypass surgery, heart failure, rapid heartbeat, preventing blood clots, and high blood pressure after a heart transplant.
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