Do omega-3 fatty acids effectively treat hypertriglyceridemia (high triglyceride levels) and reduce the risk of coronary heart disease?

Updated: Jul 23, 2021
  • Author: Mary Ellen T Sweeney, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Omega-3 fatty acids are attractive because of their low risk of major adverse effects or interaction with other medications. At high doses (≥4 g/d), triglycerides are reduced. The triglyceride-lowering impact of fish oils is entirely dependent on the omega-3 content, and, therefore, the number of capsules required for a total dose of 4 g/d requires determining the content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) per capsule. A recent study of nonprescription fish and krill oil capsules available in the United States as dietary supplements showed that the content of DHA ranges from 0.05 to 0.22 mg/g and of EPA from 0.08 to 0.45 mg/g. The labels of the most common fish oil supplement capsules in the United States claim to provide 180 mg of EPA and 120 mg of DHA per capsule. Therefore, a minimum dose of 4 g of omega-3 fatty acids per day may require at least 8-12 capsules. [71]

Low doses of EPA and DHA (750-1000 mg/d) that do not affect lipid levels have been demonstrated to lower the incidence of fatal coronary events, probably due primarily to its antiarrhythmic properties. [72]

However, the role of omega-3 fatty acid supplements in coronary heart disease (CHD) prevention is controversial, with conflicting results derived from large trials of the fatty acids. For example, a meta-analysis by Aung et al indicated that in high-risk patients, daily supplements of marine-derived omega-3 fatty acids produce no significant reduction in the rate of fatal or nonfatal CHD or other major vascular events. However, a 2017 scientific statement update from the American Heart Association declared it reasonable for omega-3 fatty acid supplementation to be used in patients with prior CHD or heart failure with reduced ejection fraction, while European guidelines state that more evidence is required before use of these supplements can be justified. [73, 74]

A retrospective study by Kim et al found that, using a baseline triglyceride level of 200-500 mg/dL, patients with hypertriglyceridemia who took omega-3 fatty acid experienced a greater reduction in triglyceride levels after 3 months than did those receiving statin monotherapy. However, the investigators found no significant difference in triglyceride decrease between those patients on omega-3 fatty acid monotherapy and those being administered a combination of omega-3 fatty acid and a statin. The study also found that at a baseline triglyceride level of 500 mg/dL or above, triglyceride reduction did not differ significantly between all the three groups. The study included 2071 patients. [75]

A retrospective, observational cohort study by Tatachar et al found that even a suboptimal dose of over-the-counter (OTC) fish oil supplement can significantly lower triglyceride levels. The investigators found that in patients who were prescribed 2 g/day of fish oil supplements, triglycerides were reduced by 29%. However, patients in the study who were prescribed fenofibrate or gemfibrozil achieved greater triglyceride reduction, 48.5% and 49.8%, respectively. [76]

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