Fish Oil in Health and Disease

LOUISVILLE, KENTUCKY. Harold Bays, MD at the Louisville Metabolic and Atherosclerosis Research Center has addressed the question, “Does therapy with fish oils rich in omega-3 fatty acids increase the risk of bleeding, and are they contraindicated in patients treated with antiplatelet and anticoagulant therapies?” Dr. Bays concludes that clinical trial evidence does not support the idea that fish oils (EPA [eicosapentaenoic acid] and DHA [docosahexaenoic acid]) increase bleeding, even when given in combination with aspirin or warfarin. He also makes two other interesting observations:

  • Fish oils inhibit thrombosis and may thus decrease the risk of ischemic stroke. However, one needs to take at least 1000 mg of EPA + DHA (not just 1000 mg of fish oil) a day to achieve significant cardiovascular benefits.
  • It may be wise to stop supplementation 4-7 days prior to major surgery, except in the case of coronary artery bypass surgery where continued supplementation may help prevent post-procedure atrial fibrillation.

Dr. Bays also addressed the question, “Do prescription and/or supplement omega-3 fatty acid products contain excessive vitamin or toxins, such as mercury, polychlorinated biphenyls, dioxin, or other contaminants, in sufficient concentrations to pose a potential health risk?” Again, his answer is negative. This conclusion is largely based on a 2006 ConsumerLab evaluation of 42 commercially available fish oil supplements. All but two were found to contain the amount of EPA and DHA stated on the label, were free of mercury, PCBs and dioxins, and were not oxidized (rancid). Among the brands that passed the ConsumerLab evaluation were Carlson, Coromega, Metagenics, Nordic Naturals, Kirkland and Puritan Pride.

Dr. Bays cautions that a high intake through the consumption of large amounts of fish may present a risk for environmental toxin exposure, especially methylmercury, PCBs, organochlorine pesticides and dioxins. He points out that oxidized mercury is insoluble in oil, so would not be expected to represent a significant toxicity risk in fish oil supplements.

In an accompanying editorial Dr. William Harris of the University of South Dakota emphatically endorses Dr. Bays’ conclusion that fish oils do not increase bleeding risk even if taken in combination with aspirin or warfarin.
Bays, HE. Safety considerations with omega-3 fatty acid therapy. American Journal of Cardiology, Vol. 99, No. 6A, March 19, 2007, pp. 35C-43C
Harris, WS. Omega-3 fatty acids and bleeding – Cause for concern? American Journal of Cardiology, Vol. 99, No. 6A, March 19, 2007, pp. 44C-46C

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