If a chicken eats a diet heavy in omega-3s — such as flaxseed and other nutrient-dense grains — its eggs will be fortified with higher levels of those healthy fatty acids. If you can afford a little extra expense, look for omega-3-enriched eggs from humanely raised chickens that roam free and forage for insects and plants, which give the eggs even further nutrients and health benefits.
Pregnancy and breast-feeding: Fish oil is LIKELY SAFE when taken by mouth appropriately. Taking fish oil during pregnancy does not seem to affect the fetus or baby while breast-feeding. Women who are pregnant or who may become pregnant, and nursing mothers should avoid shark, swordfish, king mackerel, and tilefish (also called golden bass or golden snapper), as these may contain high levels of mercury. Limit consumption of other fish to 12 ounces/week (about 3 to 4 servings/week). Fish oil is POSSIBLY UNSAFE when dietary sources are consumed in large amounts. Fatty fish contain toxins such as mercury.
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.
Irish AB, Viecelli AK, Hawley CM, et al; Omega-3 Fatty Acids (Fish Oils) and Aspirin in Vascular Access Outcomes in Renal Disease (FAVOURED) Study Collaborative Group. Effect of fish oil supplementation and aspirin use on arteriovenous fistula failure in patients requiring hemodialysis: A randomized clinical trial. JAMA Intern Med. 2017;177(2):184-193. View abstract.

The randomized trials assessing the efficacy of fish oil supplementation on secondary prevention of CAD lend further evidence to the findings that fish oil may protect from sudden cardiac death.36 The Diet and Reinfarction Trial (DART),37 one of the first randomized trials of fish oil in CAD, has been interpreted as potential support for fish oil’s role in sudden death reduction because the primary outcome of all-cause mortality occurred within 2 months of the trial’s onset.38 After such a short time span, it was believed that atherosclerosis would not be altered and therefore another mechanism was reducing mortality. This was further supported by the fact that nonfatal MIs were not reduced. Although the actual modes of death other than CAD-related deaths were not documented, it has been postulated to be secondary to a reduction in sudden death.39 The Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto Miocardico-Prevenzione40 (GISSI-Prevenzione) trial, a larger randomized trial of fish oil in CAD, has also been interpreted as evidence for fish oil’s protection against sudden death. Sudden death, however, was not a primary end point. Rather, the reduction in fatal events was driven by a reduction in cardiovascular death, which included coronary death, cardiac death, and sudden death.
Gajos, G., Zalewski, J., Rostoff, P., Nessler, J., Piwowarska, W., & Undas, A. (2011, May 26). Reduced thrombin formation and altered fibrin clot properties induced by polyunsaturated omega-3 fatty acids on top of dual antiplatelet therapy in patients undergoing percutaneous coronary intervention (OMEGA-PCI Clot). Arteriosclerosis, Thrombosis, and Vascular Biology 111.228593. Retrieved from http://atvb.ahajournals.org/content/early/2011/05/26/ATVBAHA.111.228593.abstract
The use of DHA by persons with epilepsy could decrease the frequency of their seizures. Studies have shown that children with epilepsy had a major improvement, i.e. decrease in the frequency of their seizures, but another study showed mixed results with 57 adults taking DHA supplementation. The 57 subjects demonstrated a decreased frequency of seizures for the first six weeks of the study, but for some, it was just a temporary improvement (R).
To evaluate the potential placebo effect, we made further subgrouping analyses. In the subgroups of studies using placebo controls, the omega-3 PUFAs still revealed a consistent positive anxiolytic association with anxiety symptoms. These phenomena meant that the anxiolytic effect of omega-3 PUFAs is probably not entirely owing to the placebo effect.
Subgroup meta-analysis of the anxiolytic effects of omega-3 polyunsaturated fatty acids (PUFAs) based on different EPA percentages. The anxiolytic effects of omega-3 PUFAs were significant in the subgroup with an EPA percentage less than 60% (k, 11; Hedges g = 0.485; 95% CI, 0.017 to 0.954; P = .04) but not significant in the subgroups with an EPA percentage of at least 60% (k, 9; Hedges g, 0.092; 95% CI, –0.102 to 0.285; P = .35).

Respected health care organizations proposed intake recommendations for oily fish of two servings per week for healthy adults, which equates to approximately a daily total of 500 milligrams (mg) EPA and DHA.‡ The recommendation encourages adults already with or at-risk of developing cardiovascular disease to talk to their primary healthcare professional about supplementing with amounts greater than 500 mg of EPA and DHA per day. Supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease.

56. Davidson MH, Stein EA, Bays HE, et al. COMBination of prescription Omega-3 with Simvastatin (COMBOS) Investigators. 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;29:1354–1367. [PubMed]
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.
Maximizing the benefits you get from omega-3s is highly dependent on how they are absorbed and transported throughout your body. Although these fatty acids are water soluble, they cannot be easily transported into your blood in their free form. Therefore, they need to be packaged in lipoprotein vehicles for them to be better absorbed into your bloodstream.
EPA and DHA are vital nutrients and may be taken to maintain healthy function of the following: brain and retina: DHA is a building block of tissue in the brain and retina of the eye. It helps with forming neural transmitters, such as phosphatidylserine, which is important for brain function. DHA is found in the retina of the eye and taking DHA may be necessary for maintaining healthy levels of DHA for normal eye function.

Your retina contains quite a bit of DHA, making it necessary for that fatty acid to function. (90) The National Eye Institute, part of the National Institutes of Health, concludes that there is “consistent evidence” suggesting long-chain polyunsaturated fatty acids DHA and EPA are necessary for retinal health and may help protect the eyes from disease. (91)
Dr. Holub has provided the questions and answers for several emails he has received over the years regarding omega-3 fatty acids for health.  If you have a question regarding omega-3, it is likely that Dr. Holub has answered it either here in this section, or elsewhere on the site (e.g. check the scientific overview section for general questions regarding omega-3).  To quickly find your answer, please use our search bar located in the top right section of this page.  After searching our site, and  you still cannot find the answer to your question, we invite you to ask Dr. Holub a question here.

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!

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.

A certain kidney disease called IgA nephropathy. Some research shows that long-term but not short-term use of fish oil can slow the loss of kidney function in high-risk patients with IgA nephropathy. Fish oil might have greater effects when taken at higher doses. Also, it might be most effective in people with IgA nephropathy who have higher levels of protein in the urine.