It’s Fishy

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More people than ever take fish oil dietary supplements – around eight percent in 2012 compared to five percent five years earlier, according to the National Center for Health Statistics. Advice from the American Heart Association (AHA), including a 2017 science advisory recommendation, is to consider fish oil supplementation for patients with a recent myocardial infarction, or heart attack. Unfortunately, a recent analysis of 10 large clinical trials came to the disappointing conclusion that the popular capsules do little to protect people with heart disease. This new analysis, which was published in January of this year, looked at randomized trials of marine-derived omega-3 fatty acid supplements involving almost 78,000 study participants with a history of coronary artery disease, stroke, or diabetes. The trials lasted over four years and compared fish oil to placebo or no treatment. All told, the fish oil supplements did not reduce the risk of coronary heart disease deaths, fatal or non-fatal strokes, revascularization procedures (coronary artery bypass surgery and stents), and all-cause mortality. The supplements also didn’t protect against major vascular events in any subgroups, including people with a history of heart disease, diabetes, high cholesterol, or statin (i.e. Lipitor) use.

These findings are just the latest evidence to cast doubt on the use of fish oil supplements to prevent major cardiovascular disease. While early trials showed promise, more recent trials have revealed disappointing results. This includes two 2012 studies plus a 2016 systematic review from the Agency for Healthcare Research and Quality. Many experts have expressed little surprise at the lack of effectiveness of fish oil supplements. They agree that fish oil supplements had become sort of the “supplement du jour.” The explanation for these poor results may be found in the aggressive way heart disease is treated today. The use of statins, beta-blockers, ACE inhibitors, aspirin, and procedures to restore blood flow may largely explain why the early appearance of benefits  from fish oil has largely disappeared. In addition, healthier diets, which include increased fish consumption, may have reduced the benefit of supplements over time. The AHA has yet to change its advice to include fish oil supplements in those with or at risk to develop heart disease, most likely because the supplements do not have a down side. That is, they do no harm and are relatively cheap.

There are ongoing major trials that are looking at the ability of fish oils to prevent the development of heart disease in those who do not have it, otherwise known as primary prevention. The results of these large trials should be published in the next year or two. In the meantime, people without heart disease as well as those with it should focus on making healthy lifestyle and dietary decisions, as well as monitoring their blood pressure and lipid levels. That being said, most people in the U.S. don’t eat that much fish. While the consumption of seafood is rising, it presently accounts for only five percent of protein consumption, far less than the 20 percent recommended by the Dietary Guidelines for Americans. It is possible that fish oil supplements will have a greater effect in those who consume little to no fish.

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