Fish oil is a commonly consumed supplement which is derived from fatty fish, such as mackerel, herring, lake trout and sardines. Fish oil can be taken in prescription and non-prescription forms and is often used to lower your risk of having a heart attack. Fish oil can cause an increase in the levels of some of your forms of cholesterol, but this does not usually outweigh the benefits of fish oil.
Omega-3 Fatty Acids
Fish oil's beneficial effects are a result of its omega-3 fatty acid content. Omega-3 fatty acids are a kind of unsaturated fat which is important for the function of the nervous system and also for regulating growth and development, the University of Maryland Medical Center notes. Your body does not have the enzymes to make these fats, so they must come from your diet or from supplements. As a result, omega-3 fatty acids are sometimes called "essential" fats.
Effects on Lipids
Omega-3 fatty acids, such as those found in fish oil, affect the way your body synthesizes and regulates lipid levels in your blood. The main blood lipids are triglycerides and cholesterol. Fish oil increases the levels of HDL cholesterol or "good" cholesterol, though some people also develop an increase in LDL or "bad" cholesterol as well. Fish oil also lowers your triglyceride levels, which helps reduce your risk of having a heart attack or stroke.
Cholesterol Changes Explained
Fish oil can cause your total cholesterol measurement to increase, but some of that comes from an increase in your HDL cholesterol, which is actually beneficial. The concern with fish oil is the increase in LDL cholesterol. However, this increase in the amount of LDL measured may not represent a true increase in LDL cholesterol. As health central explains, your LDL levels are calculated from measurements of your other kinds of lipids. A decrease in triglyceride levels coupled with increased amounts of HDL can cause your calculated LDL levels to rise, even if your LDL levels stay the same.
Net Effects
Even if taking fish oil does raise your cholesterol slightly, consuming fish oil has other cardiovascular benefits which outweigh this potential risk. According to the University of Maryland Medical Center, fish oil protects you against atherosclerosis and reduces your risk of having a heart attack or stroke. Consumption of high doses of fish oil can increase your risk of bleeding or bruising easily, so be sure to talk to a doctor before taking fish oil supplements.
