Something Fishy About Omega-3 Supplements

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Stephen PropatierBy Stephen Propatier via Skeptoid

The Huffington Post recently published an article by Dr. Neal Barnard, MD. It is titled “New Study explodes the Eskimo Myth” and it makes some very salient points about the development of the supplement fish oil, its historical roots, and subsequent evaluations of its benefits. This was a pleasure to read—a rare science-based examination by the Huffington Post. Dr. Barnard points out that the original conclusions from investigating fish oil appear to be tainted by researcher error. The seminal 1976 survey  had demonstrated abnormally low rates of heart disease among Inuit despite a high fat diet. But further research has shown that the original study was in fact poorly done and did not properly evaluate the true health history of the Inuit. A recent study in the Canadian Journal of Cardiology reviewed the original 1976 research and outlined its major flaws. In  2003 and 2009  follow-up studies demonstrated higher levels of cardiovascular disease among the Inuit peoples, essentially invalidating the hypotheses. If Inuit diets are not cardio-protective what does that say about diets high in Omega-3 fatty acids overall? What does this mean to fish oil supplementation?

SnakeOil-250pxFish oil was developed out of the so-called “Eskimo Anomaly”: the observation that Inuit consumed a relatively high-fat diet rich in blubber and fatty fish, yet also appeared to have low rates of heart disease. As with the “French Paradox,” scientists proposed a possible cardiovascular protective benefit from diets high in Omega-3 fatty acids, a proposition that has formed the basis of fish oil supplementation. The idea that fish oil can help prevent heart disease is has now become entrenched conventional wisdom. But if the original study has been invalidated, we must reconsider whether or not fish oil is actually beneficial. Is the discovery of fish oil a lucky accident or is it just snake oil?

It would seem highly improbable that an incorrect guess about the Inuit’s health would lead to an effective cardiovascular treatment, but it’s not impossible. Science is filled with happy accidents. The fact that fish oil was discovered due to an erroneous evaluation actually says nothing about the effectiveness of the treatment. Fish oil is one of the very few supplements in the United States to have been developed into a prescription drug, called Lovaza. Its active ingredient is Omega-3-acid ethyl esters, which are metabolized by the body into Omega-3 fatty acids. This drug is prescribed to lower serum triglycerides. Randomized, controlled research does show that it seems to be of moderate benefit for hypertriglyceridemia, a condition that predisposes people to cardiovascular disease and prancreatitis.

alternative-medicine-for-dummies_150pxUnfortunately, proponents of complementary and alternative medicine (CAM) often suggest that fish oil treats a variety of related and unrelated illness. In CAM, the uses for supplements seem to always exceed the evidence; fish oil is no different for them, and has been recommended to treat everything from cancer to headaches. Despite the large amount of research surrounding fish oil, CAM proponents always seem to find areas that haven’t been studied, using what I call the “drug of the gaps argument” and using what we don’t know about supplements to make wild speculation about benefits. In other words, if we haven’t done any studies for fish oil’s effect on stubbed toes, their assumption is that it will probably cure stubbed toes. Fish oil has tons of research, a lot is known about it and it is safe to say that we have a good grasp of what it can and cannot do. I think it is useful to review what is currently known about the supplement, highlighting what it is most commonly purported to treat as well as its problems.

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