The key component of fish oil supplements is omega-3, which is a fatty acid. Doctors tout omega-3 as a way to keep your heart healthy. It can also reduce the overall risk of sudden death in patients with coronary heart disease. Some studies also show that fish oil is beneficial in lowering high triglyceride levels, which are fats related to cholesterol [source: WebMD].
Some older people use fish oil to stem the effects of glaucoma and macular degeneration. According to scientists, the body does not produce its own omega-3 fatty acids, so eating a lot of fish or taking fish oil supplements is important. Omega-3 has proven useful in reducing pain and swelling, and for preventing blood from easily clotting [source: WebMD].
However, there are some side effects. Taking too much fish oil can cause the blood to run too thin, increasing the chance of bleeding. High doses might also harm the body's immune system, reducing a person's ability to fight disease. Fish oil can interact with birth control pills, too [source: WebMD].
Fish oil comes in soft gel capsules. Doctors recommend taking 1 to 4 grams of fish oil a day if you're fighting high triglyceride levels. Those suffering from high blood pressure should take 4 grams a day. Those with depression can also benefit from fish oil. Doctors recommend taking 9.6 grams a day in conjunction with anti-depressant medications [source: WebMD].