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Fish & Fish Oil: Separating the Facts and the Myths

shutterstock_190288550By Ben Kligler, MD
The focus on the potential of fish and fish oil to reduce our chance of heart attack and other cardiovascular disease dates back to two Danish scientists in the 1970s, who published an article making the claim that Alaska and Inuit Natives had a lower rate of heart attacks which they attributed to the high intake of fish and seal blubber in the native diet. As it turns out, these indigenous groups actually have a similar rate of heart disease as do non-native residents of Alaska and Greenland. But the cascade of research that followed from the now-disproven claim of the Danish researchers has as it turns out shown that high intake of fish may in fact reduce our chances of heart disease and stroke. A meta-analysis which summarized this research—including seventeen different studies with a total of over 315,000 patients—found that eating fish between one and four times per week decreased the risk of dying from heart
disease by 10-15%.1
So, if fish is good for us—and if the hypothesis as to why is that the omega-three essential fatty acids in fish have an anti-inflammatory effect which leads to reduced rates of heart disease—then what about the idea that we could get the same benefit without eating fish, by just taking fish oil supplements, which contain those same omega-threes. Over the last four decades, billions and billions of dollars have been spent on fish oil products based on the theory that the extracted oils would have the same effects as eating fish. But sometimes our love for pills just doesn’t pan out—as we have found with many other vitamins and supplements which, when taken in pill or liquid form, do not seem to have the same health benefits as they do when eaten in their natural state as part of the foods in our diet. As it turned out, this was the case with fish oil. A 2018 meta-analysis summarizing the results of 79 studies with a total of 112,059 participants clearly showed that for adults with varying levels of cardiovascular risk, taking fish oil supplements had no impact on the rate of heart attack or stroke, or on the overall mortality from cardiovascular disease. 2 Fish oil supplements, as it turns out, are not as good for us as actually eating fish!
To be fair, other studies have shown that fish oil supplements can be beneficial in a number of other conditions as part of the treatment approach, probably because of their anti- inflammatory effect. They help lower high triglycerides and can help reduce pain and other symptoms in patients with rheumatoid arthritis. It also turns out that DHA (docsahexaenoicacid)—one of the two essential fatty acids in fish oil—is critical in the early development of children’s brains, and infant formula in the U.S. is now routinely fortified with DHA. Other possible uses of fish oil are still worth exploring, especially in conditions driven by inflammation: in fact, The Deirdre Imus Environmental Health CenterⓇ is currently running a clinical trial of fish oil to see if it might be helpful in reducing symptoms in healthcare workers experiencing Long COVID. So, fish oil extracts and supplements certainly do have their place in promoting health.
The current state of the science tells us we should follow the American Heart Association recommendation and eat fish at least two times a week, particularly fish high in omega-threes like salmon, sardines, and lake trout.3 There’s a bit more to know about choosing healthy fish though, as some fish can contain high levels of mercury and should be avoided, especially by women of childbearing age. Those fish include shark, swordfish, king mackerel and tilefish, among others; the FDA has a more complete set of guidelines for which fish to choose to avoid mercury.4 Another issue we really need to pay attention to is trying to avoid fish species that have been heavily overfished and which in some cases are at risk for the future of the species. Examples here include Atlantic Halibut, Bluefin Tuna, and Chilean Sea Bass, and lots more information can be found through the Monterrey Bay Aquarium Seafood Watch.5
The last question to look at is which is better: farm-raised or wild caught fish? The answer to this one is “it depends.” Farm-raised fish get a bad rap in some circles—supposedly more likely to be contaminated with PCBs and other chemicals, less nutritious, bad for the environment. But the fact is that fish farmed in sound and environmentally sustainable ways can sometimes be actually a better choice, because the water they are raised in can be more closely monitored for contaminants than can the big wide ocean where wild fish are grown. The best answer to this “it depends” is to look for sources of fish, whether farmed or wild, that can be trusted to transparently share information about where the fish is sourced, and what the standards and conditions of the suppliers are for quality and safety.
Dr._KliglerDr. Kligler is the Medical Advisor for The Deirdre Imus Environmental Health Center®. He is also the National Director of the Integrative Health Coordinating Center for the Veterans Health Administration and Research Director for the Office of Patient Centered Care & Cultural Transformation. He was the founding  Director  of the Beth Israel Fellowship Program in Integrative Medicine, and teaches in the Beth Israel Residency Program in Urban Family Practice. Dr. Kligler is the author of Curriculum in Complementary Therapies: A Guide for the Medical Educator, and co-editor of Integrative Medicine: Principles for Practice, a textbook published by McGraw-Hill. He is also Co-Editor-in-Chief of the peer-reviewed journal Explore: The Journal of Science and Healing.
1 Zheng J, Huang T, Yu Y, Hu X, Yang B, Li D. Fish consumption and CHD mortality: an updated meta-analysis of seventeen cohort studies. Public Health Nutr. 2012 Apr;15(4):725-37
2 Abdelhamid AS, et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database of Systematic Reviews 2018, Issue 7. Art. No.: CD003177. DOI: 10.1002/14651858.CD003177.pub3.
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