In the never-ending pursuit to becoming the healthiest version of themselves, many people will try just about any supplement. They'll take one supplement to improve exercise performance, another to boost brain power, and something else to support a healthy heart.
Fish oil is a versatile supplement that may offer many tantalizing benefits at once, across a broad spectrum of areas: brain function, help with fat loss, and workout recovery, to name a few. It's embraced by a wide demographic, too: Everyone from hardcore bodybuilders to the elderly see fit to pop these capsules daily.
Which of these benefits are proven, and which are open to speculation? We poured through the research to identify the top five evidence-based reasons you should be supplementing with fish oil.
Reason 1: Your heart is the most important muscle in your body
Cardiovascular disease has been the leading cause of death in the United States since 1921. A healthy diet and exercise can help you avoid becoming part of that statistic, and so can fish oil.
Fish oil is an excellent source of omega-3 fatty acids, which have been shown to benefit people with healthy hearts as well as those at high risk for cardiovascular disease. Fish oil helps prevent heart disease by decreasing triglyceride levels, slowing the development of plaque in arteries, and lowering blood pressure.[2-4]
Reason 2: Shaping up doesn't end when your workout does
If you suffer from sore muscles or achy joints after you exercise…well, you're just like 95 percent of the rest of us mortals. Even highly trained athletes can feel sore and tender after a major workout. Sure, you could wait 48-72 hours for the discomfort to pass on its own—or you could hasten the recovery process by taking fish oil.
In studies of omega-3-rich fish oil supplementation, individuals reported less pain, reduced inflammation, and a greater range of motion when taking fish oil versus a placebo. This is most likely due to fish oil's ability to strengthen cell membranes, reduce oxidative stress that occurs with strenuous exercise, and lessen the body's inflammatory response to exercise.[5,6] Improved recovery means you can train more often and at a higher intensity for greater progress.
Reason 3: Your brain needs all the help it can get
Research suggests that fish oil may also help enhance cognitive performance because of the way omega-3s, specifically EPA and DHA, support nervous system development and repair. Further research among healthy participants suggests that taking omega-3s can also improve reaction time, higher-level brain function, and decision-making.
Among healthy older adults, fish oil supplementation has been shown to improve brain function, lending support to the theory that it might help older adults maintain their cognitive abilities.
Reason 4: Many of us could stand to lose a little weight
Research studies have shown that supplementing with fish oil can help you feel more full after meals, so you're less likely to reach for seconds or thirds. If you're already on a reduced-calorie diet and exercise regularly, supplementing with fish oil can help you lose more body fat than if you dieted and exercised without it.[9,10]
Researchers suspect that this greater weight loss is due to fish oil's ability to increase fat oxidation, which refers to your body's ability to break down fat to use for fuel. Better fat breakdown means that instead of storing fat, your body uses it to fuel your daily activities.
Reason 5: You'll have more glycogen saved for intense activities
By improving your body's ability to use fat for fuel, fish oil can help your body store more muscle glycogen. This news should be music to any endurance athlete's ears. Supplementing a healthy diet with fish oil for three weeks has been shown to increase fat metabolism during endurance exercise. Similar studies on exercise and metabolic response to omega-3 supplementation suggest that people are more able to use fat stores for energy, sparing their stored glycogen for the most intense exercise.
Research has also shown that supplementation can help hearts work more efficiently during rest and exercise. A more efficient heart could likely improve blood flow to working muscle, thereby having a direct positive effect on exercise performance.
How to Optimize Your Health and Performance
For optimum heart health and exercise performance, supplement with 1-2 grams of EPA/DHA per day. If you eat fatty fish 2-3 times per week, you're probably getting enough omega-3s already. But if your diet lacks fish, consider investing in a quality supplement that contains twice as much EPA as DHA and is free of heavy metals. Companies will often put it on their label, website, or both if they have third-party testing to remove heavy metals and any other possible contaminants.
Because consuming fish oil supplements can cause digestive symptoms and potential "fishy taste," you may want to consume your supplements with another food item or with a meal.
Although not extremely common, consuming too much omega-3 fatty acid can lead to decreased blood clotting ability and platelet aggregation. Most people should consume no more than 4 grams per day. 
- Achievements in Public Health, 1900-1999: Decline in Deaths from Heart Disease and Stroke—United States, 1900-1999. (1999). Retrieved from https://www.cdc.gov/mmwr/preview/mmwrhtml/mm4830a1.htm
- Morris, M. C., Sacks, F., & Rosner, B. (1993). Does fish oil lower blood pressure? A meta-analysis of controlled trials. Circulation, 88(2), 523-533.
- Balk, E. M., Lichtenstein, A. H., Chung, M., Kupelnick, B., Chew, P., & Lau, J. (2006). Effects of omega-3 fatty acids on serum markers of cardiovascular disease risk: a systematic review. Atherosclerosis, 189(1), 19-30.
- Goodfellow, J., Bellamy, M. F., Ramsey, M. W., Jones, C. J., & Lewis, M. J. (2000). Dietary supplementation with marine omega-3 fatty acids improve systemic large artery endothelial function in subjects with hypercholesterolemia. Journal of the American College of Cardiology, 35(2), 265-270.
- Kelly B. Jouris, Jennifer L. McDaniel, Edward P. Weiss, (2011) The Effect of Omega-3 Fatty Acid Supplementation on the Inflammatory Response to eccentric strength exercise. Journal of Sports Science and Medicine, (10), 432 - 438.
- Tartibian, B., Maleki, B. H., & Abbasi, A. (2009). The effects of ingestion of omega-3 fatty acids on perceived pain and external symptoms of delayed onset muscle soreness in untrained men. Clinical Journal of Sport Medicine, 19(2), 115-119.
- Fontani, G., et al. Cognitive and physiological effects of Omega‐3 polyunsaturated fatty acid supplementation in healthy subjects. European Journal of Clinical Investigation, 35.11 (2005): 691-699.
- Witte, A. V., Kerti, L., Hermannstädter, H. M., Fiebach, J. B., Schreiber, S. J., Schuchardt, J. P., ... & Flöel, A. (2013). Long-chain omega-3 fatty acids improve brain function and structure in older adults. Cerebral Cortex, bht163.
- Parra, D., Ramel, A., Bandarra, N., Kiely, M., Martínez, J. A., & Thorsdottir, I. (2008). A diet rich in long chain omega-3 fatty acids modulates satiety in overweight and obese volunteers during weight loss. Appetite, 51(3), 676-680.
- Hill, A. M., Buckley, J. D., Murphy, K. J., & Howe, P. R. (2007). Combining fish-oil supplements with regular aerobic exercise improves body composition and cardiovascular disease risk factors. The American Journal of Clinical Nutrition, 85(5), 1267-1274.
- Mickleborough, T. D. (2013). Omega-3 polyunsaturated fatty acids in physical performance optimization. International Journal of Sport Nutrition and Exercise Metabolism, 23(1), 83-96.
- Delarue, J., Labarthe, F., & Cohen, R. (2003). Fish-oil supplementation reduces stimulation of plasma glucose fluxes during exercise in untrained males. British Journal of Nutrition, 90(04), 777-786.
- Walser, B., & Stebbins, C. L. (2008). Omega-3 fatty acid supplementation enhances stroke volume and cardiac output during dynamic exercise. European Journal of Applied Physiology, 104(3), 455-461.