Omega-3 Fatty Acids (oils), which include eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are found primarily in fish (such as mackerel, lake trout, herring, sardines, albacore tuna, and salmon) and some plants. While they are necessary for the proper functioning of our bodies, the levels necessary for health benefits are more than can readily be achieved through diet alone. These oils are used as supplemental treatments for an array of conditions including heart disease, diabetes, and arthritis. They also play a role in brain development and function.
There is strong evidence from epidemiological (population) studies that cultures which eat large amounts of fish containing these oils have a low incidence of depression. These population studies have been followed up with randomized double-blind experiments (highly controlled studies that use an active and non-active medicine; neither patients nor experimenters are aware of who receive the active medicines and who do not). While many of these later highly-controlled studies suggested a relationship between treatment with Omega-3 oils and lessening of depressive symptoms, other studies have produced contradictory results. In other words, not all studies suggest positive treatment effects. Some study subjects showed a 50% reduction in scores (lower scores indicate less depression) on the Hamilton Depression Rating Scale, while other subjects receiving fish oils were no different than people who received a placebo (a preparation which contains no active ingredients).
Because EPA and DHA play many essential roles in the body and brain, CAM practitioners and the American Heart Association suggest that most people should supplement their diets with these oils. Overall, the evidence suggests that EPA/DHA is also a good supplement for people with depression. However, additional studies are needed to fully understand what role these oils play in treating mood disorders.
Safety and Dosing
Normal dosing for the omega-3 fatty acids is between 1-4 grams a day. Results have been achieved with as little as 1 gram of a good-quality supplement. Most fish-oil supplements contain about 18% EPA/DHA, so to get a gram of the EPA/DHA one should take approximately five 1-gram supplements.
Fish oils have been shown to both lower cardiovascular (heart) disease risk and raise cholesterol in some people. Likewise, EPA and DHA lowers blood sugar in diabetics while raising it in other people. If you are taking medications for diabetes, your dosing may require adjustment. If you are considering taking more than 1 gram of EPA/DHA a day, and are on medications for diabetes or cardiovascular disease, you should consult with your health professional. Side effects of Omega-3 Oils include stomach upset, nosebleeds, and loose stools. Most side effects from taking fish oils are mild. Fish oils may act as an anticoagulant (e.g., as a blood thinner), so consult with your health provider if you are taking any other blood-thinning medications. It can be dangerous when blood becomes too thin.