FISH OIL SUPPLEMENTATION: CURRENT STATUS


The American Heart Association has issued a science advisory1 on the effects of omega-3 polyunsaturated fatty acid (fish oil) supplementation and its possible role in prevention of cardiovascular disease. They reviewed many randomized controlled trials and focused on the common indications for these supplements related to whether or not fish oil can prevent any diseases. Prior recommendations for patients with existent coronary heart disease were updated and new recommendations made for patients with other problems that included patients with diabetes and prediabetes and those with high risk for heart disease, stroke, heart failure, and atrial fibrillation (heart rhythm disorder). Their recommendations are presented below:

  • Treatment with fish oil supplementation is reasonable for retarding advancement of disease in patients who have already suffered from problems such as a prior heart attack (myocardial infarction) or from established reduced heart function.
  • Treatment with these supplements is, however, not recommended to prevent strokes in those suffering from atrial fibrillation, or in patients with diabetes, unless their risk of developing heart disease is excessively high.
  • Finally, the available evidence does not support the use of fish oil supplements in the general population who are not at high cardiovascular disease risk, including those with diabetes.

COMMENT

As I have stated previously, prior data have demonstrated a prevention of cardiovascular problems in individuals who consume fish (which contain omega–3 fatty acids), at least twice a week. This has led to randomized trials that evaluate the effect of fish oil supplements alone on cardiovascular outcomes. A potential mechanism by which they may decrease serious outcomes is through their ability to decrease the likelihood of serious or fatal heart rhythm disorders (ventricular fibrillation), in those who are already afflicted with such disorders. I also emphasize that this AHA statement refers to evidence-based recommendations about supplementing diet with fish oil, and this does not apply to eating fish or replacing meat with fish as a part of a healthy lifestyle.

The bottom line in the AHA statement is that fish oil may be beneficial for those already afflicted with heart disease. However, there is no evidence to support its use for prevention of cardiovascular disease in either low or medium-risk individuals from the general population. Furthermore, most of the evidence suggested no effect even in high-risk individuals such as those with a strong family tendency to develop these maladies, though there was a lack of consensus for these particular individuals. Therefore, use of these products is not helpful in most people who have shown no tendency to develop such problems. But, for all of us, the lifestyle dietary patterns that should be followed are still clearly in force!

1 Siscovick DS, Barringer TA, Fretts AM, et al. Omega-3 polyunsaturated fatty acid (fish oil) supplementation and the prevention of clinical cardiovascular disease: A science advisory from the American Heart Association. [Published online ahead of print March 13, 2017]. Circulation. doi:10.1161

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POLYUNSATURATED FATS: MORE SUPPORT FOR THEIR USE

For many years, we have recommended decreasing dietary saturated fats (primarily from animal sources) and substituting unsaturated (vegetable or fish sources) as a probable means for warding off cardiovascular diseases. Now the supporting evidence is even more compelling, for a new long-term study from Sweden has shown that unsaturated fats likely confer greater longevity from not only cardiovascular diseases, but other maladies as well. From over 4,400 study subjects (age 60 or more), researchers found that higher blood levels of EPA and DHA—the primary omega-3 fats found in fish and fish oil—were associated with lower risk of death from cardiovascular diseases in both men and women. Inexplicably, however, men also showed a 41% reduction in mortality from all causes when those with the highest levels of linoleic acid—the main component of most liquid vegetable oils such as soybean and corn oil—were compared with those possessing the lowest levels.

HEALTHY FATS: These are the fats found in fish, many vegetable oils, and nuts. The heart-healthy benefits of the omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) were first observed in the 1970s among the native Inuit populations of Greenland, who consumed lots of fatty fish and had low rates of heart disease. Many subsequent studies have confirmed these results. Linoleic acid has been in the spotlight more recently, showing reductions of cardiovascular disease in men, but, as results accumulate, women will likely also share in these benefits.

CONCLUSION: Regardless of these apparent minor discrepancies, it is clear that substituting the polyunsaturated fats constitutes a more effective approach to nutrition, exceeding any benefits that might result from merely reducing saturated fats alone.

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