The Cochrane researchers found that increasing long-chain omega 3 provides little if any benefit on most outcomes that they looked at. They found high certainty evidence that long-chain omega 3 fats had little or no meaningful effect on the risk of death from any cause. The risk of death from any cause was 8.8% in people who had increased their intake of omega 3 fats, compared with 9% in people in the control groups.
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).
Meta-analyses (research that combines and analyzes results of multiple studies) generally suggest that the omega-3s are effective, but the findings are not unanimous because of variability between doses, ratios of EPA to DHA, and other study design issues. The most effective preparations appear to have at least 60% EPA relative to DHA. While DHA is thought to be less effective as an antidepressant, it may have protective effects against suicide. Recent work at Massachusetts General Hospital and Emory University suggests that depressed individuals who are overweight and have elevated inflammatory activity may be particularly good candidates for EPA treatment.
Many people focus on the dosage of fish oil to take, like 1000 mg or 1200 mg, but it is the omega-3s that matter. This is where the benefits of fish oil are found. The two types of omega-3 fatty acids to focus on are EPA and DHA. These omega-3s are naturally found in oily fish like salmon, halibut, sardines and anchovies, and are the very reason why fish oil supplements have received such high praise.
In many cases, people are recommended to consume fish oil because it is an easy way to get additional omega-3 fatty acids into their diet. Omega-3 fats can be used to reduce swelling or to prevent blood clots which could cause major cardiovascular damage. There are many other conditions which can be decreased or improved with the use of fish oil. In most cases fish oil is used to help reduce high triglycerides which can cause serious conditions like diabetes or heart disease.
Despite this one study, you should still consider eating fish and other seafood as a healthy strategy. If we could absolutely, positively say that the benefits of eating seafood comes entirely from omega-3 fats, then downing fish oil pills would be an alternative to eating fish. But it’s more than likely that you need the entire orchestra of fish fats, vitamins, minerals, and supporting molecules, rather than the lone notes of EPA and DHA.
Fish oil is also extremely beneficial for pregnant women and their children. Throughout pregnancy and also while breastfeeding, a woman’s omega-3 needs are even higher than usual. According to the American Pregnancy Association, most U.S. women are deficient in EPA and especially DHA going into pregnancy and get even more depleted during pregnancy, as the placenta supplies the fetus with DHA from the mother’s tissue. Omega-3 DHA is a critical building block of the fetal brain, eyes and nervous system. Once the baby is born, omega-3s continue to be vital to healthy brain development and immune function. (30)
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.
Among the 16 studies comparing the effect of omega-3 PUFA treatment with that of the placebo,33,34,36,47-49,51-53,55-61 the main results revealed a significantly greater association of treatment with reduced anxiety symptoms in patients receiving omega-3 PUFA treatment than in those not receiving it (k, 16; Hedges g, 0.372; 95% CI, 0.032-0.712; P = .03; eFigure 3 in the Supplement). The meta-analysis of the subgroup focusing on non–placebo-controlled trials also showed a significantly greater association of treatment with reduced anxiety symptoms in patients receiving omega-3 PUFA treatment than in those not receiving it (k, 3; Hedges g, 0.399; 95% CI, 0.154-0.643; P = .001).35,50,54
Damage to the kidneys caused the drug cyclosporine. Cyclosporine is a medication that reduces the chance of organ rejection after an organ transplant. Taking fish oil seems to prevent kidney damage in people taking this drug. Fish oil also seems to improve kidney function during the recovery phase following the rejection of a transplanted organ in people taking cyclosporine.