Doses for depression range from less than 1 g/day to 10 g/day, but most studies use doses between 1 and 2 g/day. In my practice, I recommend 1 to 2 g/day of an EPA+DHA combination, with at least 60% EPA, for major depression. I am more cautious in patients with bipolar depression, because the omega-3s may bring on mania, as can most antidepressants. In these individuals, I recommend using omega-3 cautiously, and preferably in combination with a prescription mood stabilizer.

van der Meij, B. S., Langius, J. A., Smit, E. F., Spreeuwenberg, M. D., von Blomberg, B. M., Heijboer, A. C., Paul, M. A., and van Leeuwen, P. A. Oral nutritional supplements containing (n-3) polyunsaturated fatty acids affect the nutritional status of patients with stage III non-small cell lung cancer during multimodality treatment. J.Nutr. 2010;140(10):1774-1780. View abstract.
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These conversions occur competitively with omega−6 fatty acids, which are essential closely related chemical analogues that are derived from linoleic acid. They both utilize the same desaturase and elongase proteins in order to synthesize inflammatory regulatory proteins.[50] The products of both pathways are vital for growth making a balanced diet of omega−3 and omega−6 important to an individual's health.[77] A balanced intake ratio of 1:1 was believed to be ideal in order for proteins to be able to synthesize both pathways sufficiently, but this has been controversial as of recent research.[78]

Anxiety, the most commonly experienced psychiatric symptom, is a psychological state derived from inappropriate or exaggerated fear leading to distress or impairment. The lifetime prevalence of any anxiety disorder is reported to be approximately 1 in 3.1 Anxiety is often comorbid with depressive disorders2 and is associated with lower health-related quality of life3 and increased risk of all-cause mortality.4 Treatment options include psychological treatments, such as cognitive-behavioral therapy and pharmacological treatments, mainly with selective serotonin reuptake inhibitors.5 Individuals with anxiety and related disorders tend to be more concerned about the potential adverse effects of pharmacological treatments (eg, sedation or drug dependence) and may be reluctant to engage in psychological treatments that can be time-consuming and costly, as well as sometimes limited in availability.6 Thus, evidence-based and safer treatments are required, especially for anxious patients with comorbid medical conditions.
Kabir, M., Skurnik, G., Naour, N., Pechtner, V., Meugnier, E., Rome, S., Quignard-Boulange, A., Vidal, H., Slama, G., Clement, K., Guerre-Millo, M., and Rizkalla, S. W. Treatment for 2 mo with n 3 polyunsaturated fatty acids reduces adiposity and some atherogenic factors but does not improve insulin sensitivity in women with type 2 diabetes: a randomized controlled study. Am.J.Clin.Nutr. 2007;86(6):1670-1679. View abstract.
The hypotriglyceridemic effect of fish oil is well established and is related to both dose and baseline triglyceride level. Patients with triglycerides <90 mg/dL will be negligibly affected unless very high doses of omega-3 FA are used.67,68 However, in patients with triglycerides >200 mg/dL, who are treated with 4 g/d of fish oil, a 30% reduction in triglycerides is expected.17,69 For patients with triglycerides >500 mg/dL who are at risk for pancreatitis, the National Cholesterol Education Program Adult Treatment Panel III guidelines recommend using fish oil supplements as an adjunctive therapy to fibrates and nicotinic acid.70 Lovaza capsules have been shown to be effective, safe, and comparable to gemfibrozil in treating triglycerides at this range.71,72 The official label recommendation for Lovaza is for patients with triglycerides >500 mg/dL.73
Omega 3 fatty acids are monounsaturated fats that come from food sources—primarily cold water fish (eg, salmon, trout, tuna, mackerel, and herring)—that contain EPA (eicosapentaenoic acid) and docosahexaenoic acid (DHA). Other fatty acids are derived from plant-derived sources of food—including nuts (especially walnuts) and seeds (eg, flax, chia, sunflower)—that have primarily ALA (alpha-linolenic acid).
Due to the anticipated heterogeneity, a random-effects meta-analysis was chosen rather than a fixed-effects meta-analysis because random-effects modeling is more stringent and incorporates an among-study variance in the calculations. The entire meta-analysis procedure was performed on the platform of Comprehensive Meta-analysis statistical software, version 3 (Biostat). Under the preliminary assumption that the scales for anxiety symptoms are heterogeneous among the recruited studies, we chose Hedges g and 95% confidence intervals to combine the effect sizes, in accordance with the manual of the Comprehensive Meta-analysis statistical software, version 3. Regarding the interpretation of effect sizes, we defined Hedges g values 0 or higher as a better association of treatment with reduced anxiety symptoms of omega-3 PUFAs than in controls. For each analysis, a 2-tailed P value less than .05 was considered to indicate statistical significance. When more than 1 anxiety scale was used in a study, we chose the one with the most informative data (ie, mean and standard deviation [SD] before and after treatment). We entered the primary outcome provided in the included articles or obtained from the original authors. As for the variance imputation, we mainly chose the mean and SD before and after treatment. Later, we entered the mean and SD and calculated the effect sizes based on the software option, standardized by post score SD. In the case of studies with 2 active treatment arms, we merged the 2 active treatment arms into 1 group. If these 2 active treatment arms belonged to different subgroups (ie, different PUFA dosage subgroups), we kept them separate. Regarding the numbers of participants counted, we chose intention-to-treat as our priority. If there were insufficient data in the intention to treat group (ie, some studies only provided the changes in anxiety severity in those participants completing trials), we chose instead the per-protocol numbers of participants.
Between the ages of five and 65, the majority of the body’s needs can be met by using EPA-rich oils and eating fish, marine products, organic greens and pastured animal products. EPA levels are under constant demand and low EPA levels in adolescents and adults correlates strongly with development of mental health issues, including depression, dyslexia and dyspraxia, heart problems, joint and bone conditions, as well as neurodegenerative diseases such as MS and Parkinson’s. EPA also protects our genes and cell cycle, as well as helping to keep our stress response regulated, so an adequate supply of EPA throughout adult life can help prevent a range of chronic illness.

Omega AD study, Irving et al. (54) Double-blind, placebo-controlled, randomized 1741 DHA (1.7 g/d) and EPA (0.6 g/d) for 6 mo, then for all subjects (supplementation group and placebo group) Supplementation was associated with positive weight gain and appetite in supplementation group at 6 mo, but not in the placebo group, and for both groups at 12 mo
Since 2004, scientists have been suggesting that the omega-3 index be used as a way to measure a person’s risk of cardiovascular disease, in a similar way to how cholesterol levels are used today (1). A recent study funded by the National Institutes for Health even indicated that the omega-3 index could be a better predictor of death risk than serum cholesterol levels (2).
Jump up ^ Siscovick DS, Barringer TA, Fretts AM, Wu JH, Lichtenstein AH, Costello RB, Kris-Etherton PM, Jacobson TA, Engler MB, Alger HM, Appel LJ, Mozaffarian D (2017). "Omega−3 Polyunsaturated Fatty Acid (Fish Oil) Supplementation and the Prevention of Clinical Cardiovascular Disease: A Science Advisory From the American Heart Association". Circulation. 135 (15): e867–84. doi:10.1161/CIR.0000000000000482. PMID 28289069.
DHA is one of the most prevalent fatty acids in the brain. This could partly explain why our brains do better with a greater supply. A Rush Institute for Healthy Aging study analyzed fish-eating patterns of more than 800 men and women, ages 65 to 94. Those eating fish at least once a week were much less likely to develop Alzheimer's disease than those who turned up their nose at it.
Chemical structure of alpha-linolenic acid (ALA), an essential omega−3 fatty acid, (18:3Δ9c,12c,15c, which means a chain of 18 carbons with 3 double bonds on carbons numbered 9, 12, and 15). Although chemists count from the carbonyl carbon (blue numbering), biologists count from the n (ω) carbon (red numbering). Note that, from the n end (diagram right), the first double bond appears as the third carbon-carbon bond (line segment), hence the name "n-3". This is explained by the fact that the n end is almost never changed during physiological transformations in the human body, as it is more energy-stable, and other compounds can be synthesized from the other carbonyl end, for example in glycerides, or from double bonds in the middle of the chain.
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.
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]
Agency for Healthcare Research and Quality. Effects of Omega-3 Fatty Acids on Lipids and Glycemic Control in Type II Diabetes and the Metabolic Syndrome and on Inflammatory Bowel Disease, Rheumatoid Arthritis, Renal Disease, Systemic Lupus Erythematosus, and Osteoporosis. AHRQ Publication No. 04-E012-1; 2004. Available at: (Accessed February 7, 2017).
The Department of Ecology of the State of Washington has ranked various seafood based on its EPA and DHA concentrations. The highest-ranking seafood is mackerel, excluding King mackerel, that has a concentration of 1,790 milligrams of combined EPA and DHA per 100 grams, followed by salmon at 1,590; bluefin tuna has between 1173 and 1504 milligrams; sardines contain 980 milligrams; albacore tuna has 862 milligrams; bass has 640 milligrams; tuna has 630 milligrams; trout and swordfish have 580 milligrams; and walleye has 530 milligrams. Other seafood, which includes sea bass, clams, lobster, scallops, catfish, cod, pollock, crayfish and scallops contains between 200 and 500 milligrams of EPA and DHA per 100 grams. Breaded fish products rank lowest on the list with only 0.26 milligram per 100 grams.

Studies have also found that omega-3 fatty acids from fish oil are associated with improved survival rates for heart attack victims. A study published in the medical journal Circulation found that people who took a high dose of fish oil each for six months following the occurrence of a heart attack actually improved their hearts’ overall functioning and also reduced biomarkers of systemic inflammation. (20)
Augood, C., Chakravarthy, U., Young, I., Vioque, J., de Jong, P. T., Bentham, G., Rahu, M., Seland, J., Soubrane, G., Tomazzoli, L., Topouzis, F., Vingerling, J. R., and Fletcher, A. E. Oily fish consumption, dietary docosahexaenoic acid and eicosapentaenoic acid intakes, and associations with neovascular age-related macular degeneration. Am J Clin Nutr 2008;88(2):398-406. View abstract.
Omega-3s have been studied for other conditions, with either inconclusive or negative results. These conditions include allergies, atopic eczema (an allergic skin condition), cystic fibrosis, diabetes, inflammatory bowel diseases (Crohn’s disease or ulcerative colitis), intermittent claudication (a circulatory problem), nonalcoholic fatty liver disease, and osteoporosis. 

Bergmann, R. L., Haschke-Becher, E., Klassen-Wigger, P., Bergmann, K. E., Richter, R., Dudenhausen, J. W., Grathwohl, D., and Haschke, F. Supplementation with 200 mg/day docosahexaenoic acid from mid-pregnancy through lactation improves the docosahexaenoic acid status of mothers with a habitually low fish intake and of their infants. Ann Nutr Metab 2008;52(2):157-166. View abstract.
High blood pressure. Fish oil seems to slightly lower blood pressure in people with moderate to very high blood pressure. Some types of fish oil might also reduce blood pressure in people with slightly high blood pressure, but results are inconsistent. Fish oil seems to add to the effects of some, but not all, blood pressure-lowering medications. However, it doesn't seem to reduce blood pressure in people with uncontrolled blood pressure who are already taking blood pressure-lowering medications.