Cholesterol is a wax-like substance that naturally occurs in your body and in some foods. Some forms of cholesterol, high-density lipoprotein or HDL, is good for you. For instance, it helps to lower bad cholesterol, which is low-density lipoprotein, or LDL. High levels of cholesterol increase your risk of cardiovascular disease. Fish oil contains fatty acids that help to improve factors that contribute to high cholesterol. However, it may also cause side effects, so consult your doctor before taking it.
Fatty Acids in Fish Oil
Fatty fish such as salmon, tuna, herring, sardines and mackerel contain oils rich in the omega-3 fatty acids eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA. These monounsaturated fats have proven benefits for treating heart disease. Also known as essential fatty acids, omega-3 fats have anti-inflammatory properties. However, they must come from your diet; your body cannot produce them.
Triglycerides and High Cholesterol
People with high cholesterol often have high blood levels of triglycerides that, like cholesterol, are blood fats or lipids. Triglycerides and cholesterol can combine with each other and with other substances to create a plaque buildup along the walls of your arteries. Fish oil can help to lower triglyceride levels, slow the formation of plaque and possibly prevent heart disease and stroke, according to the University of Maryland Medical Center. Also, people with omega-3-rich diets tend to have higher levels of HDL cholesterol.
Evidence
In a systematic review published in the November 2006 issue of the journal "Atherosclerosis," researchers from Tufts-New England Medical Center found that across 27 fish oil studies, higher fish oil dose was associated with greater reductions in blood triglyceride levels. Fish oil also caused modest increases in high-density lipoprotein, but had no effect on total cholesterol levels, which are the levels of both HDL and LDL cholesterol. Also, a Japanese study published in the "International Journal of Hypertension" in March 2011 found that taking 2 g. of DHA supplements daily for five weeks significantly increased high-density lipoprotein cholesterol and significantly reduced total cholesterol in Scottish men who rarely ate fish.
Dosage and Side Effects
For general health, you can get fish oil from food by consuming 3.5 oz. of fatty fish at least twice a week. Alternatively, take a fish oil capsule with 500 mg of DHA and EPA daily, recommends Leslie Beck, a registered dietitian and author of "The Complete Nutrition Guide for Women." However, if you're trying to lower triglycerides and cholesterol, you may need to take between 2 and 4 g. of fish oil daily under the care of a physician. Fish oil can cause side effects such as bleeding, gas, belching and diarrhea. It can also interact with blood-thinning medications.
Considerations
Some studies show no effect of fish oil on cholesterol, such as one conducted by a team of researchers from New Zealand and Australia and published in the journal "Stroke" in 2009. The researchers suggest that lack of effect of the fish oil may be due to dosage, oxidation of the fish oil --- that can occur with improper storage --- and how long you take the supplement. Your doctor can recommend an appropriate dose, as well as other methods to lower cholesterol, such as reducing your intake of saturated and trans fats, exercising regularly and losing weight.
References
- American Heart Association: About Cholesterol
- American Heart Association: Fish 101
- American Heart Association: What Are High Blood Cholesterol and Triglycerides
- University of Maryland Medical Center: Omega-3 Fatty Acids
- "Atherosclerosis"; Effects of Omega-3 Fatty Acids on Serum Markers of Cardiovascular Disease Risk: A Systematic Review; E.M. Balk; Nov 2006
- "International Journal of Hypertension"; Effects of Docosahexaenoic Acid Supplementation On Blood Pressure, Heart Rate, and Serum Lipids in Scottish Men with Hypertension and Hypercholesterolemia
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