Widenhorn-Müller  K, Schwanda  S, Scholz  E, Spitzer  M, Bode  H.  Effect of supplementation with long-chain ω-3 polyunsaturated fatty acids on behavior and cognition in children with attention deficit/hyperactivity disorder (ADHD): a randomized placebo-controlled intervention trial.  Prostaglandins Leukot Essent Fatty Acids. 2014;91(1-2):49-60. doi:10.1016/j.plefa.2014.04.004PubMedGoogle ScholarCrossref
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.
Maclean, C. H., Mojica, W. A., Morton, S. C., Pencharz, J., Hasenfeld, Garland R., Tu, W., Newberry, S. J., Jungvig, L. K., Grossman, J., Khanna, P., Rhodes, S., and Shekelle, P. 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. Evid.Rep.Technol.Assess.(Summ.) 2004;(89):1-4. View abstract.
Bianconi, L., Calo, L., Mennuni, M., Santini, L., Morosetti, P., Azzolini, P., Barbato, G., Biscione, F., Romano, P., and Santini, M. n-3 polyunsaturated fatty acids for the prevention of arrhythmia recurrence after electrical cardioversion of chronic persistent atrial fibrillation: a randomized, double-blind, multicentre study. Europace. 2011;13(2):174-181. View abstract.
The human body can make most of the types of fats it needs from other fats or raw materials. That isn’t the case for omega-3 fatty acids (also called omega-3 fats and n-3 fats). These are essential fats—the body can’t make them from scratch but must get them from food. Foods high in Omega-3 include fish, vegetable oils, nuts (especially walnuts), flax seeds, flaxseed oil, and leafy vegetables.

As always with such trials, you can never prove zero benefit (or zero risk), but an essentially negative trial or meta-analysis sets statistical limits on the size of any remaining plausible effect. What we can now say with a fairly high degree of confidence is that any health benefit from consuming omega-3 fatty acids is tiny, probably too small to warrant supplementing (or adding it to pasta).

Some research indicates that people who eat more seafood may have a reduced risk of cognitive decline. However, omega-3 supplements haven’t been shown to help prevent cognitive impairment or Alzheimer’s disease or to improve symptoms of these conditions. For example, a large NIH-sponsored study completed in 2015 indicated that taking EPA and DHA supplements did not slow cognitive decline in older adults. The people studied were participants in a larger eye disease study, and all of them had age-related macular degeneration (AMD). 
Depression. There is inconsistent evidence on the effect of taking fish oil for depression. Some research shows that taking fish oil along with an antidepressant might help improve symptoms in some people. Other research shows that taking fish oil does not improve depression symptoms. The conflicting results may be due to the amount of EPA and DHA in the supplement or the severity of depression before treatment.
The way that fish oil does that is to interfere with carbohydrate metabolism, and in insulin-resistant people or in people with specific genetic differences that might predispose them to having very high triglycerides, you do benefit from interfering that pathway with the fish oil, but I would actually try a low-carbohydrate diet in a lot of those situations to see if that helps with lowering triglycerides, or in the case of insulin resistance, I would try to address the insulin resistance at its root cause.

• Fish oil – Fish oil is among the primary ways that people enhance their intake of omega-3 fats. High-quality fish oils can certainly provide many health benefits. However, this oil is weak in antioxidants. This means that as you increase your omega-3 intake through fish oil consumption, you actually increase your need for added antioxidant protection.
FDA pregnancy category C. It is not known whether Fish Oil will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using Fish Oil. It is not known whether omega-3 polyunsaturated fatty acids pass into breast milk or if this could harm a nursing baby. Do not use Fish Oil without telling your doctor if you are breast-feeding a baby. Do not give this medication to anyone under 18 years old.
Gerber, J. G., Kitch, D. W., Fichtenbaum, C. J., Zackin, R. A., Charles, S., Hogg, E., Acosta, E. P., Connick, E., Wohl, D., Kojic, E. M., Benson, C. A., and Aberg, J. A. Fish oil and fenofibrate for the treatment of hypertriglyceridemia in HIV-infected subjects on antiretroviral therapy: results of ACTG A5186. J.Acquir.Immune.Defic.Syndr. 4-1-2008;47(4):459-466. View abstract.
ADD ADHD Ageing Allergies Alzheimer's Arthritis Autism baby Behaviour Brain function Cancer CFS Chronic Fatigue Concentration Dementia Depression Diabetes Digestion Dyslexia Dyspraxia Energy EPA Fertility Fibromyalgia General Health Good fats Healthy omega-3 Heart health Hormones IBS Immune System Inflammation Joints M.E. Mental health Mood Omega-3 Pregnancy Psoriasis Skin Sleep Stress Vegetarian nutrients Vegetarian Omega-3 Weight management

They also found that taking more long-chain omega 3 fats (including EPA and DHA), primarily through supplements probably makes little or no difference to risk of cardiovascular events, coronary heart deaths, coronary heart disease events, stroke or heart irregularities. Long-chain omega 3 fats probably did reduce some blood fats, triglycerides and HDL cholesterol. Reducing triglycerides is likely to be protective of heart diseases, but reducing HDL has the opposite effect. The researchers collected information on harms from the studies, but information on bleeding and blood clots was very limited. 

The chemical structure of eicosapentaenoic acid and docosahexaenoic acid. Eicosapentaenoic acid consists of 20 carbons (C20) with 5 double bonds, and the last unsaturated carbon is located third from the methyl end (n-3). Do-cosahexaenoic acid consists of 22 carbons (C22) with 6 double bonds, and also with the3 last unsaturated carbon located third from the methyl end (n-3). Adapted with permission from Frishman et al, eds. Cardiovascular Pharmacotherapeutics. New York, NY: McGraw Hill; 2003.3

Why would someone foul a perfectly good box of rotini with omega 3 oils? This is based on the belief that omega 3 fatty acids reduce heart disease and vascular risk, probably through reducing blood pressure and cholesterol. This is a plausible claim, but as we see over and over again in medicine, plausibility (while nice) is insufficient as a basis for clinical claims.
"Fish is still the mainstay of the diet in many parts of the world where there is very little heart disease," he says. "I think when you replace higher fat foods and highly processed foods with fish there is going to be some benefit.'' So it may be that by substituting fish for red meats, bacon and luncheon meats, and similar high-fat foods, you are making a change that will lead to improving your health outcomes, he says.
Although results from studies regarding the disease processes of AD seem to be promising, there are conflicting data regarding the use of omega-3 fatty acids in terms of cognitive function. Neuropsychiatric symptoms accompany AD from early stages and tend to increase with the progression of the disease (55). An analysis of 174 patients randomized to a placebo group or to a group with mild to moderate AD (MMSE score ≥15) treated with daily DHA (1.7 g) and EPA (0.6 g) found that at 6 mo, the decline in cognitive function did not differ between the groups. Yet, in a subgroup with very mild cognitive dysfunction (n = 32, MMSE score >27), they observed a significant reduction in the MMSE decline rate in the DHA+EPA-supplemented group compared with the placebo group (47). Another study that looked at DHA supplementation in individuals with mild to moderate AD used the Alzheimer's Disease Assessment Scale–Cognitive subscale, which evaluates cognitive function on a 70-point scale in terms of memory, attention, language, orientation, and praxis. This study found that DHA supplementation had no beneficial effect on cognition during the 18-mo trial period for the DHA group vs. placebo (56).
Abnormal rapid heart rhythms (ventricular arrhythmias). Population research suggests that eating a lot of fish has no effect on the risk for abnormal rapid heart rhythms. Clinical research is inconsistent. Some research shows that taking fish oil daily does not affect the risk for abnormal heart rhythms. But other research shows that taking fish oil for 11 months delays the development of the condition. However, overall, taking fish oil does not seem to reduce the risk of death in people with abnormal rapid heart rhythms.