Omega-3 fatty acids, and heart disease: Do fish oil supplements prevent heart attacks or death from heart disease

In recent years, a steady stream of experts, including the ubiquitous Dr. Oz, Screen shot 2013-01-26 at 9.47.51 AMhave advised every one to take fish oil supplements to protect their heart health

In fact, there is little to no evidence that fish oil supplements or fish oil enhanced foods should be consumed for any health purpose.
Omega-3 fatty acids (also known as  ω−3 or n−3) are polyunsaturated fatty acids (PUFA) that can be derived from marine or plant oils. They are considered essential fatty acids in humans, vital for normal metabolism but not synthesized by the human body.

The long chain omega-3 fatty acids eicosapentanoic acid (EPA) and docosahexanoic acid (DHA)  are felt to be the most beneficial. The best food source of DHA and EPA is cold water fatty fish and shellfish. The fish highest in these fatty acids are salmon, sardines, mackerel, herring and tuna.

Alpha-linolenic acid (ALA) is an omega-3 fatty acid which is predominantly found in plant oils (flaxseed, canola, and soybean oils) and walnuts. It can, to a limited extent, be converted in human bodies  to EPA and DHA, thus can be considered a precursor.

There is some evidence that consuming fish on a regular basis is associated with lower risk of coronary heart disease and stroke. Therefore, I can agree with current AHA and USDA guidelines which recommend consumption of fatty fish at least twice a week and I advise this for my patients.

Predominantly on the basis of one very positive study performed in Italy in 1999 (the GISSI study, which gave EPA/DHA to heart attack survivors), most cardiologists, the AHA, and the supplement industry had concluded by 2005 that fish oil reduced mortality and cardiac morbidity. The best evidence then was that the fish oil supplement was helpful after a heart attack (so-called secondary prevention). However, there was a very powerful urge to extrapolate this recommendation to patients without heart disease (so-called primary prevention).

Such expanded recommendations were reflected in the media. For example, Forbes proclaimed

“One Supplement That Works:

A lot of nutritional supplements are quack medicines. Not fish oil”

By 2009 sales of OTC fish oil supplements had risen 18% in one year to 739 million and Americans were buying 1.8 billion worth of foods (such as margarine and peanut butter) fortified with extra omega-3s. By  2011, Americans were spending 1.1 billion on supplements.

GlaxoSmithKline developed and patented a high-concentration fish oil (Lovaza) that gained an indication for treating high triglycerides which had global sales of 1 billion dollars in 2008. Supported by heavy advertising and promotion to physicians (through dinner lectures, lunches and other promotions), this expensive version of fish oil is widely prescribed by physicians for reasons other than the very high triglyceride elevations it has an indication for.

Forbes wrote

“In the history of nutritional supplements there’s something striking about omega-3: the fact that it works. Much of the $25 billion a year that Americans spend on supplements is money down the drain”

While the second part of that sentence is true (the vast majority of supplements/nutraceuticals/minerals that Americans take in a search for longevity or arthritis relief are worthless) the first part is not true.

The subsequent  hype for the benefits of fish oil supplements, especially in the world of nutritional supplement has been outrageous and inaccurate.

A typical product description reads as follows.

“We believe this is the highest quality Omega-3 available.
This highly concentrated Pharmaceutical Grade Omega-3 Fish Oil delivers 800mg of EPA and 600mg of DHA.
The important benefits of Omega-3 have been proven in thousands of independent studies by universities, governments, and health organizations. Because of such research, people around the world are now taking fish oil for reasons ranging from brain development, mild depression and heart function to arthritis and our immune systems.
It causes NO fishy or un-pleasant after taste.
This Omega 3 has been verified by a 3rd party to be Mercury Free.”

If one reads further down the page, however, the most important sentence is the following (and this is true for all supplements_






These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure or prevent any disease

So , the fish oil pushers  make a series of totally unsubstantiated claims about the benefits followed by the statement that it is not intended to benefit any one in any way.

The most recent systematic review and meta-analysis of omega-3 fatty acid supplementation and the risk of major cardiovascular events (published Sept. 2012,) concluded:

“overall, omega-3 PUFA supplementation was not associated with a lower risk of all-cause mortality, cardiac death, sudden death, myocardial infarction,  or stroke based on relative and abolute measures of association”

Studies performed in the last 5 years of omega-3 PUFA supplementation do not support a role for them in reducing heart disease, either in high risk individuals without documented heart disease or those who have already had heart attacks.

Most of my patients continue to take fish oil supplements because they think that there may be a benefit without any down side. However, there are a number of potential down sides that should be considered.
1. There is no government regulation or measurement of the contaminants in fish oil supplements.
According to Consumer Reports

“Most tested pills are claimed to be “purified” or “free” of PCBs, mercury, or other contaminants, claims that have no specific regulatory definition, the Food and Drug Administration says. The agency has taken no enforcement action against any omega-3 maker over PCBs or other contaminants, an FDA spokeswoman said, because it has seen no public-health risk”

2. A major source of the fish oil in fish oil supplements, menhaden, is being over fished. Menhaden are a sardine-like forage fish that range in huge schools from Canada to Florida and into the Gulf. As filter feeders, they form an important base of the marine food chain. They have historically been harvested for food and later, for use as fertilizer and more recently for use in aquaculture and in omega-3 supplements. This fish, which has been called “the most important fish in the sea,” feeds on phytoplankton and is essential for a healthy marine ecosystem. The Atlantic States Marine Fisheries Commission (ASMFC) recently approved a 20% decrease in fish catch for the Atlantic Coast menhaden bait and reduction fisheries, The numbers of these fish have declined by 90% in the last 4 decades. Without doing extensive research on your particular fish oil supplement you can’t be sure you aren’t contributing to  this problem.

So, the bottom line on fish oil supplements is that  the most recent scientific evidence does not support any role for them  in preventing heart attack, stroke, or death. There are potential down sides to taking them, including contaminants and the impact on the marine ecosystem. I don’t take them and I advise my patients to avoid them (unless they have triglyceride levels over 500.)

Americans want a “magic-bullet” type pill to take to ward off aging and the diseases associated with it. There isn’t one. Instead of buying pills and foods manipulated and processed by the food industry which promise better health, I advise following Michael Pollan’s simple advice

“Eat food. Mostly plants. Not too much”

13 thoughts on “Omega-3 fatty acids, and heart disease: Do fish oil supplements prevent heart attacks or death from heart disease”

  1. Very good read! looking forward to more posts! Have a question about recommended diet: How does one reconcile low-carb and alcohol, or low-carb and oatmeal as being conflicting recommendations for heart healthy diet?

    1. Leeza,
      Thank you. If you want to follow a really, really low carb diet , as some recommend, then you probably need to avoid alcohol . However, I’m not an advocate of extremely low carb (ketosis inducing) diets and I it’s clear that 1 or 2 alcoholic beverages per day improve HDL and are associated with lower heart disease risk. I haven’t studied oatmeal enough to make any worthwhile comments. I think oatmeal’s heart health benefits have been overstated. You can make it a very poor breakfast choice by loading on sugar. Good topic for a later blog, though.

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    1. Jeff, the article you referenced is from 2002. In 2002 the best evidence did suggest a slight benefit for fish oil supplementation in patients with heart attacks. Since then, the scientific evidence , which I reference in my post,has almost completely refuted any benefits of routinely taking fish oil supplementation. Interestingly, the New York Times published an article a few days ago which highlighted the inconsistent quality of fish oil supplements and quoted authorities who confirmed my position that there is no good evidence that fish oil supplements reduce your risk of cardiovascular disease.
      Unfortunately, early in the article, the author invokes the AHA as supporting fish oil supplements based on that same 2002 review paper. Then, a horribly biased source is quoted to add legitimacy to the practice:

      “I think it’s one of the most important supplements people can take,” said Dr. Maroon, who is also chair of the medical advisory board for GNC, the nation’s largest specialty retailer of dietary supplements. “The omega-3 fatty acids are essential for so many functions in the body.”

      This logic or lack thereof is what is driving the 1.2 billion dollar annual fish oil supplement business which continues to thrive despite a lack of evidence supporting efficacy and safety. It iss disappointing that the New York Times piece which should have been focusing on the problems with fish oil and the lack of evidence supporting its widespread usage, included such an outdated reference and quoted a clearly financially biased source.

  3. Are you familiar with Dr William Davis and his program to reverse arterial plaque? Among other things he uses is fish oli – your thoughts?

    1. I am familiar with “wheat belly” William Davis. He writing and recommendations are not based on good scientific studies. He has no studies published in the scientific literature on the effects of his nutritional recommendations. Nothing he has written convinces me that fish oil reverses arterial plaque. I would place him in the category of fad diet promoter, bordering on snake-oil salesman (except he is not selling products, just very misleading books).

      1. Charles
        Thanks for you comments.
        I’m not impressed with this study at all.
        It is uncontrolled with multiple interventions including statin therapy.
        Doesn’t support omega-3 or Vit D supplmentation at all.
        Dr Anthony Pearson

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