Given the wide-ranging importance and benefits of marine omega-3 fatty acids, it is important to eat fish or other seafood one to two times per week, particularly fatty (dark meat) fish that are richer in EPA and DHA. This is especially important for women who are pregnant or hoping to become pregnant and nursing mothers. From the third trimester until the second year of life, a developing child needs a steady supply of DHA to form the brain and other parts of the nervous system. Many women shy away from eating fish because of concerns that mercury and other possible contaminants might harm their babies, (9) yet the evidence for harm from lack of omega-3 fats is far more consistent, and a balance of benefit vs. risk is easily obtained. (To learn more about the controversy over contaminants in fatty fish, read Fish: Friend or Foe.)
This systematic review and meta-analysis of clinical trials conducted on participants with clinical anxiety symptoms provides the first meta-analytic evidence, to our knowledge, that omega-3 PUFA treatment may be associated with anxiety reduction, which might not only be due to a potential placebo effect, but also from some associations of treatment with reduced anxiety symptoms. The beneficial anxiolytic effects of omega-3 PUFAs might be stronger in participants with specific clinical diagnoses than in those without specific clinical conditions. Larger and well-designed clinical trials should be performed with high-dose omega-3 PUFAs, provided as monotherapy and as adjunctive treatment to standard therapy.
My estimate is that close to 90 percent of fish oils on the market today may contain mercury and pesticide residues plus hydrogenated oils. Of course, this is my opinion based on my own research from visiting different manufacturing plants, interviewing companies, and studying the research and the listed ingredients of typical fish oils. I would stay away from ALL fish oils that do not have antioxidants like astaxanthin, which help stabilize the oil from going rancid. I always look for astaxanthin as part of any high-quality fish oil supplement.
Interestingly, the results are also consistent with our recent findings that somatic anxiety is associated with omega-3 PUFA deficits and the genetic risks of PUFA metabolic enzyme cytosolic phospholipase A2 in major depressive disorder62,63 and interferon α–induced neuropsychiatric syndrome.63,64 Brain membranes contain a high proportion of omega-3 PUFAs and their derivatives and most animal and human studies suggest that a lack of omega-3 PUFAs in the brain might induce various behavioral and neuropsychiatric disorders,16,65-70 including anxiety-related behaviors.12,18,19,32,49,71 Emerging evidence suggests that omega-3 PUFAs interfere with and possibly control several neurobiological processes, such as neurotransmitter systems, neuroplasticity, and inflammation,12,72 which is postulated to be the mechanism underlying anxiety and depression.

Several large studies have linked higher blood levels of long-chain omega-3s with higher risks of prostate cancer. However, other research has shown that men who frequently eat seafood have lower prostate cancer death rates and that dietary intakes of long-chain omega-3s aren’t associated with prostate cancer risk. The reason for these apparently conflicting findings is unclear. 
Studies have also shown that omega-3 fats are anti-arrhythmic (preventing or counteracting cardiac arrhythmia), anti-thrombotic (prevents thrombosis or a blood clot within a blood vessel), anti-atherosclerotic (preventing fatty deposits and fibrosis of the inner layer of your arteries), and anti-inflammatory (counteracting inflammation – the heat, pain, swelling, etc).
A 2012 study involved children from 6 to 12 years of age with ADHD who were being treated with methylphenidate and standard behavior therapy for more than six months. The parents of these children reported no improvement in behavior and academic learning using these standard treatments. The researchers randomly gave some of the children an omega-3 and omega-6 acid supplementation or a placebo. They found “statistically significant improvement” for the omega group in the following categories: restlessness, aggressiveness, completing work and academic performance. (5)
Hanwell, H. E., Kay, C. D., Lampe, J. W., Holub, B. J., and Duncan, A. M. Acute fish oil and soy isoflavone supplementation increase postprandial serum (n-3) polyunsaturated fatty acids and isoflavones but do not affect triacylglycerols or biomarkers of oxidative stress in overweight and obese hypertriglyceridemic men. J Nutr 2009;139(6):1128-1134. View abstract.
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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.

In my opinion, the key benefit of DHA lies in its unique spatial characteristics. As mentioned earlier, the extra double bond (six in DHA vs. five in EPA) and increased carbon length (22 carbons in DHA vs. 20 in EPA) means that DHA takes up takes up a lot more space than does EPA in the membrane. Although this increase in spatial volume makes DHA a poor substrate for phospholipase A2 as well as the COX and LOX enzymes, it does a great job of making membranes (especially those in the brain) a lot more fluid as the DHA sweeps out a much greater volume in the membrane than does EPA. This increase in membrane fluidity is critical for synaptic vesicles and the retina of the eye as it allows receptors to rotate more effectively thus increasing the transmission of signals from the surface of the membrane to the interior of the nerve cells. This is why DHA is a critical component of these highly fluid portions of the nerves (7). On the other hand, the myelin membrane is essentially an insulator so that relatively little DHA is found in that part of the membrane.
Protects Vision: Our eyes' retinas are a membranous structures and the whole eye is covered in a soft double layer of membranes, making your eyes' health dependent on the liver (who knew?). The liver helps metabolize fat-soluble vitamins that feed and maintain those membranes. If you're deficient in DHA, it affects how we see by delaying the system that converts light into neural energy in the retina.
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 fatty acids have been found to play a role in atherosclerosis and peripheral arterial disease (PAD). It is thought that both EPA and DHA improve plaque stability, decrease endothelial activation, and improve vascular permeability, thereby decreasing the chance of experiencing a cardiovascular event (41). It was found that EPA supplementation is associated with significantly higher amounts of EPA in the carotid plaque than placebo (P < 0.0001), which may lead to decreased plaque inflammation and increased stability (42). PAD, a manifestation of atherosclerosis, is characterized by buildup of plaque in the arteries of the leg and can eventually lead to complete blockage of the arteries. EPA+DHA supplementation has been shown to improve endothelial function in patients with PAD by decreasing plasma levels of soluble thrombomodulin from a median value of 33.0 μg/L to 17.0 μg/L (P = 0.04) and improve brachial artery flow–mediated dilation from 6.7% to 10.0% (P = 0.02) (43). Patients who had PAD and were supplemented with EPA experienced a significantly lower major coronary event HR than those who did not take EPA (HR: 0.44; 95% CI: 0.19–0.97; P = 0.041) (44).
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
If you’ve been paying attention to health headlines over the last few decades, you’ve likely heard about essential fatty acids (EFAs) — specifically omega-3s and omega-6s. These nutrients play many vital roles in supporting our overall health, including increasing nutrient absorption, ensuring proper growth and development of the brain and nervous system, and reducing the risk of chronic illnesses, such as heart disease.  Click here for a guide to understanding omega-3 and omega-6 fatty acids and how they influence your health.

The evidence that fish oil consumption should be used for primary prevention of CAD is based on observational studies. The only randomized trial for primary prevention, the JELIS trial, showed a moderate relative risk reduction and was conducted in a very specific group. Nevertheless, to date, there has been no strong signal suggesting any serious adverse effects of having high DHA and EPA oils in the diet. We agree with the national guidelines that one should consume moderate amounts of fish oil— either in supplement or through the dietary intake of fatty fish with low mercury levels.


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.
Researchers are taking a hard look at a different sort of balance, this one between possible effects of marine and plant omega-3 fats on prostate cancer. Results from the Health Professionals Follow-up Study and others show that men whose diets are rich in EPA and DHA (mainly from fish and seafood) are less likely to develop advanced prostate cancer than those with low intake of EPA and DHA. (6) At the same time, some-but not all-studies show an increase in prostate cancer and advanced prostate cancer among men with high intakes of ALA (mainly from supplements). However, this effect is inconsistent. In the very large Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, for example, there was no link between ALA intake and early, late, or advanced prostate cancer. (7)
It seems that infancy and childhood are some of the most important periods of time in a person’s life to get plenty omega-3s in their diet, probably because of the amount of long-chain fatty acids found in the brain and retina. It’s crucial for developing babies and children to get a good amount of DHA and EPA so their brains and eyes develop fully and properly. (78)
Warfarin (Coumadin) is used to slow blood clotting. Fish oil also might slow blood clotting. Taking fish oil with warfarin might slow blood clotting too much and increase the risk of bleeding. However, conflicting results suggests that fish oil does not increase the effects of warfarin. Until more is known, use cautiously in combination with warfarin. Have your blood checked regularly, as your dose of warfarin (Coumadin) might need to be changed.
People who eat seafood rich in EPA and DHA at least once a week are less likely to die of heart disease, according to the National Center for Complementary and Alternative Medicine. The fatty acids may also be helpful in relieving symptoms of rheumatoid arthritis. Fish oil has been rated as "Effective" by MedlinePlus for lowering high triglycerides, which can be a major risk factor for heart disease. Fish oil has been rated as "Likely Effective" for keeping healthy hearts free of disease. Although eating baked or broiled fish can reduce the risk of heart disease, fried fish or fish sandwiches not only cancel out any heart-healthy benefits, but may also contribute to heart disease, MedlinePlus notes.
LCn3s are long chain fatty acids from fish, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is plant-based omega 3-alpha‐linolenic acid. Fatty acids are essentially chains of carbon atoms with an OOH group at one end. The available binding sites on the carbon atoms are filled with hydrogen atoms. If every binding site is occupied with a hydrogen, that is a saturated fatty acid. If instead of hydrogen atoms there is a double bond between two adjacent carbon atoms, that is an unsaturated fatty acid. If there are multiple double bonds, that is polyunsaturated. Omega 3 fatty acids are unsaturated, with a double bond between the third and fourth carbon atoms from the end opposite the OOH group.
6. Krauss-Etschmann S, Shadid R, Campoy C, Hoster E, Demmelmair H, Jimenez M, Gil A, Rivero M, Veszpremi B, Decsi T, et al. Effects of fish-oil and folate supplementation of pregnant women on maternal and fetal plasma concentrations of docosahexaenoic acid and eicosapentaenoic acid: a European randomized multicenter trial. Am J Clin Nutr. 2007;85:1392–400. [PubMed]

ODS seeks to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, supporting research, sharing research results, and educating the public. Its resources include publications (such as Dietary Supplements: What You Need to Know), fact sheets on a variety of specific supplement ingredients and products (such as vitamin D and multivitamin/mineral supplements), and the PubMed Dietary Supplement Subset
Carrero, J. J., Fonolla, J., Marti, J. L., Jimenez, J., Boza, J. J., and Lopez-Huertas, E. Intake of fish oil, oleic acid, folic acid, and vitamins B-6 and E for 1 year decreases plasma C-reactive protein and reduces coronary heart disease risk factors in male patients in a cardiac rehabilitation program. J.Nutr. 2007;137(2):384-390. View abstract.
To our knowledge, this is the first systematic review and meta-analysis to examine the anxiolytic effects of omega-3 PUFAs in individuals with anxiety symptoms. The overall findings revealed modest anxiolytic effects of omega-3 PUFAs in individuals with various neuropsychiatric or major physical illnesses. Although participants and diagnoses were heterogeneous, the main finding of this meta-analysis was that omega-3 PUFAs were associated with significant reduction in anxiety symptoms compared with controls; this effect persisted vs placebo controls. Furthermore, the association of treatment with reduced anxiety symptoms of omega-3 PUFA were significantly higher in subgroups with specific clinical diagnoses than in subgroups without clinical conditions.
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
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.
Scaly, itchy skin (eczema). Research shows that fish oil does not improve eczema. Most research also shows that taking fish oil during pregnancy doesn't PREVENT eczema in the child. Giving fish oil to an infant also doesn't seem to prevent eczema in children. But children who eat fish at least once weekly from the age of 1-2 years seem to have a lower risk of developing eczema.
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