Wikipedia says the following about Omega 3.
N−3 fatty acids (popularly referred to as ω−3 fatty acids or omega-3 fatty acids) are essential unsaturated fatty acids with a double bond (C=C) starting after the third carbon atom from the end of the carbon chain.
Essential fatty acids are molecules that cannot be synthesized by the human body but are vital for normal metabolism. One of the two families of these essential fatty acids is the omega-3 fatty acids.
The carbon chain has two ends—the acid (COOH) end and the methyl (CH3) end. The location of the first double bond is counted from the methyl end, which is also known as the omega (ω) end or the n end.
Nutritionally important n−3 fatty acids include α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), all of which are polyunsaturated.
Common sources of n–3 fatty acids include fish oils and some plant oils such as flaxseed oil and algal oil.
That article has more information about the health benefits and risks of Omega 3.
Here are results from scientific studies of Omega 3 oils.
Men with prostate cancer who ate a low-fat diet and took fish oil supplements had lower levels of pro-inflammatory substances in their blood and a lower cell cycle progression score, a measure used to predict cancer recurrence, than men who ate a typical Western diet, UCLA researchers found.
A second large, prospective study by scientists at Fred Hutchinson Cancer Research Center has confirmed the link between high blood concentrations of omega-3 fatty acids and an increased risk of prostate cancer.
Procedures like angioplasty, stenting and bypass surgery may save lives, but they also cause excessive inflammation and scarring, which ultimately can lead to permanent disability and even death. A new research report appearing in The FASEB Journal, shows that naturally derived compounds from polyunsaturated fatty acids (omega-3s) may reduce the inflammation associated with these procedures to help arteries more fully and completely heal.
The omega 3 fatty acids in fish oil have long been thought to protect against cardiovascular disease -- so much so that the American Heart Association currently recommends eating at least two servings of fish a week, particularly fatty varieties rich in omega 3s. However, the mechanism behind this protective effect still remains a mystery. In a new study, scientists led by Jason R. Carter of Michigan Technological University shed light on this phenomenon by providing evidence that fish oil might specifically counteract the detrimental effects of mental stress on the heart. Their findings show that volunteers who took fish oil supplements for several weeks had a blunted response to mental stress in several measurements of cardiovascular health, including heart rate and muscle sympathetic nerve activity (MSNA), part of the "fight or flight" response, compared to volunteers who took olive oil instead. The results may explain why taking fish oil could be beneficial to the heart and might eventually help doctors prevent heart disease in select populations.
Fish oil supplements, also called omega 3 fatty acid capsules, raise levels of adiponectin in the bloodstream. Adiponectin is an important hormone that has beneficial effects on metabolic processes like glucose regulation and the modulation of inflammation. In long-term human studies, higher levels of adiponectin are associated with lower risks of type 2 diabetes and coronary heart disease.
Data from 185 research papers revealed, however, that fish oils do not have a direct impact on this process in these areas of the brain, but are likely to play a significant role in stalling refined sugars and saturated fats' ability to inhibit the brain's control on the body's intake of food.
Fish oil rich in DHA and EPA is widely believed to help prevent disease by reducing inflammation, but until now, scientists were not entirely sure about its immune enhancing effects. A new report appearing in the April 2013 issue of the Journal of Leukocyte Biology, helps provide clarity on this by showing that DHA-rich fish oil enhances B cell activity, a white blood cell, challenging the notion that fish oil is only immunosuppressive. This discovery is important as it shows that fish oil does not necessarily reduce the overall immune response to lower inflammation, possibly opening the doors for the use of fish oil among those with compromised immune systems.
In comparison, the team found that a dietary supplement, DHA ethyl ester, found in most fish oil pills fails to activate the same channels, and even antagonizes the positive effect of DHA from natural sources, on the cells. The DHA ethyl ester seems to compete with the natural form of DHA for binding sites on the ion channel.
Taking omega-3 fish oils could help to protect against skin cancer, according to researchers at The University of Manchester. The team has just carried out the first clinical trial to examine the impact of the fish oils on the skin immunity of volunteers. Led by Professor Lesley Rhodes, Professor of Experimental Dermatology from the Photobiology Unit Dermatology Centre at the University, the study analysed the effect of taking omega-3 on 79 healthy volunteers.
Triglyceride lipid emulsions rich in an omega-3 fatty acid injected within a few hours of an ischemic stroke can decrease the amount of damaged brain tissue by 50 percent or more in mice, reports a new study by researchers at Columbia University Medical Center.