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By Subrata Kar, D.O. and Richard Webel, MD

Omega-3 polyunsaturated fatty acids (PUFAs) found in fish oil have been reported to reduce the risk of heart disease (cardiovascular disease).  A number of studies have shown a reduction in fatal and non-fatal heart attacks, stroke, heart disease, and death.¹ Fish oil (PUFAs) also have beneficial effects in the reduction of death following a heart attack.²

Sources of Fish Oil

Daily consumption of fish oil from either fish or fish oil supplements may be beneficial in patients with heart disease.^3,4 Oily fish, such as salmon, tuna, sardines, herring, and mackerel provide natural source of fish oil.⁴ However, the consumption of oily fish may be preferred in comparison to the intake of fish oil supplements because oily fish provides Vitamin D, selenium, and naturally occurring antioxidants which are not found in fish oil supplements.³

Clinical trials have shown that fish oil may reduce total mortality by as much as 20-50 percent in doses of 0.85 to 4.0 grams/day after a duration of 12 to 42 months.² Larger doses of 3 to 4 grams per day of fish oil decreases triglycerides which provide an energy source and are components of cholesterol. The Food and Drug Administration has approved Lovaza (formerly Omacor), a highly purified form of PUFAs, for individuals with severely elevated cholesterol (hyperlipidemia) at a dose of 4 grams/daily.³ 

Effects on Cholesterol

PUFAs are essential fatty acids, hence, they cannot be synthesized by humans. Subsequently, these omega-3 fatty acids must be obtained through diet or fish oil supplements.⁵ PUFAs may lower triglycerides by 20 to 50 percent through reduction of triglyceride production and they may increase good cholesterol (HDL) by 9 percent.^6,7

PUFAs have been shown to reduce cholesterol buildup.⁸ PUFAs also display antioxidant properties which improve blood vessel function and may contribute to the beneficial effects against cholesterol buildup in the arteries of the heart.

PUFA Associated Side Effects

PUFAs are overall safe medications which are well tolerated by many individuals.  Common side effects include nausea, gastrointestinal distress, and belching.⁴ Other less frequent effects include bloating, worsening of blood sugar control, and bleeding.^9,10 These side effects may occur at doses greater than 2 grams/day.¹¹ PUFAs do not interact with statins (cholesterol lowering medications) to cause a very rare, but dangerous side effect known as rhabdomyolysis (muscle damage causing kidney failure). PUFAs used in combination with statins do not cause muscle weakness, muscle aches, or muscle cramping. The use of PUFAs with fibrates (triglyceride lowering medication) is not known to cause rhabdomyolysis. Therefore, PUFAs can be used as combination therapy with statins or fibrates to improve cholesterol levels. No known liver, muscle, or renal toxicity has been reported.  PUFAs may be safely used in combination with other cholesterol lowering medications such as statins to lower triglyceride levels.¹⁰ They may also provide beneficial effects after a heart attack.¹² However, some studies have not shown a benefit in heart disease. Thus, further clinical research is necessary before general recommendations can be advised for all individuals. 

Conclusions

PUFAs have cardiovascular benefits with a possible reduction in the incidence of death from heart disease.  Since PUFAs have with minimal side effects, it may be considered in combination with other medical therapy for heart disease as recommended by your physician.  Patients who are intolerant to statins because of muscle aches, muscle weakness, or other side effects may benefit from PUFA consumption for cholesterol reduction.  However, some studies have shown no beneficial effects of PUFAs for heart disease.  Consequently, the decision to start PUFAs for heart disease protection should be discussed with your heart doctor (Cardiologist) or Primary Care Physician so an informed and individualized decision can be made based upon your health. 

Editor's note: This article is part of a special series brought to you by Missouri Medicine, the Medical Journal of the Missouri State Medical Association (MSMA). MedHelp, Missouri Medicine, and MSMA are collaborating to educate and empower health consumers by making the latest scientific studies and medical research available to the public. Learn more about MSMA and see more from Missouri Medicine.

This is a summary of the article "Fish Oil Capsules and Supplementation for Heart Disease: The Benefits and Side Effects" by Subrata Kar, D.O. and Richard Webel, MD, which was originally published in the April/May 2012 issue of Missouri Medicine. The full article is available here.

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