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”

Taking a Multivitamin Does Not Protect Against Heart Disease

Many of my patients take a multivitamin supplement and a lot take individual vitamins or supplements. When they ask me if I think they are worthwhile I invariably say no, not from a cardiovascular standpoint. If they ask me if they should take the vitamin/supplement I usually respond that there is no evidence of harm and they should take it if some other reputable  (not a chiropractor or naturopath) physician has advised it for a particular reason.

Data from the Center for Disease Control  has shown that use of dietary supplements has increased progressively over the last decade . The graph below shows that despite evidence of no benefit , about a third of Americans continue to take a multivitamin/multimineral (defined as having 3 or more components)

MVI use
It bears emphasizing-there is no evidence  any multivitamin or vitamin improves your heart health or lowers your risk of heart disease or stroke!

This has been proven over and over again in multiple trials in which a  vitamin with proposed healthy antioxidant properties (say Vitamine E or C) or anti-inflammatory properties (say homocysteine) has gone up against placebo. The vitamin is no better than placebo.

Apparently, the message  that these chemicals are beneficial from the vitamin/nutraceutical/supplement industry is so persuasive and pervasive that my patients will continue to pay for and take their chosen vitamin or multivitamin despite my advice. The patients most likely to persist in taking the useless pills have a suspicion of doctors, the pharmaceutical industry and are convinced that “natural” methods (totally unproven by any scientific techniques) are superior to medically approved methods for disease prevention.

Nail In The Coffin for Multivitamins

The latest nail in the coffin for vitamins in the prevention of cardiovascular disease was published by Sesso et al in JAMA late last year .
This study reported data from the large, long term Physicians’ Health Study II which was  started in 1997 and ended in 2011. Over 14 thousand male physicians over the age of fifty were entered into the study. On a random basis half of them took a multivitamin and half took a placebo (thus the study was randomized and placebo-controlled). Neither the patients nor their doctors knew who was taking what (thus double blind).
The study investigators measured who had what is termed in cardiology research a major adverse cardiovascular event, known as MACE. A MACE would in this case would be a stroke, a heart attack or death from cardiovascular disease.

The results of this really well done, large, controlled trial show absolutely no benefit of multivitamins in reducing any cardiovascular outcome. Those taking multivitamins were just as likely as those taking a placebo to have heart attacks, strokes or to die from any cause.

In the interest of full disclosure an earlier publication from this same study  also in JAMA showed a very slight , barely significant lowering of risk of cancer by multivitamin use. However, the significance of these findings, given multiple other negative studies , lack of any mortality benefit, and any specific cancer effect has been widely questioned. An accompanying editorial , I think, best summarizes the weakness of the study and  the authors, very clearly do not recommend multivitamin usage for preventing cancer.

Milk Drinking and Your Risk For Heart Disease

In my previous post, I referenced USDA guidelines which recommend consuming dairy but only in a low-fat form. How did the mainstream nutritional community decide the American public should shift from full fat dairy to low or no fat dairy? Prior to the 1950s there was little concern in nutritional research about fat in the American diet. Beginning in the 1950s, it became apparent that heart disease, coronary artery disease (the cause of heart attacks) in particular, had become the major cause of mortality in western countries.

The American epidemiologist, Ancel Keys, became convinced in the mid 1950s that dietary fat and cholesterol were related to heart disease. In 1970 published his “Seven Countries Study” which found a correlation between per capita fat consumption and the prevalence of heart disease in seven cherry-picked countries. These kinds of studies can be useful for developing theories about which factors might cause disease, however, they cannot prove that a dietary factor causes the disease.

Messerli recently published a tongue-in-cheek analysis of the relationship between per capita chocolate consumption in a particular country and the number of Nobel Laureates produced by that same country that illuminates the weakness of this type of study.
This is the main figure from that study: Chocolate Consumption and Nobel Laureates

There is a very nice relationship demonstrated which suggests that the more chocolate consumed in a particular country, the more Nobel Laureates produced. However, no one would seriously believe that chocolate consumption causes the kind of brilliance needed to do achieve a Nobel prize. Clearly, there are confounding variables or factors. Sometimes, confounding factors are clear and can be accounted for, but often they are not clear and cannot be accounted for.

Early studies of this type demonstrated that there was a relatively strong association between the per capital supply of milk or some component of milk and heart disease mortality. In other studies, changes in gross milk production over time and changes in heart disease deaths were shown to correlate.

Despite the weakness of such studies in proving causation, as Gary Taubes pointed out ,

“the National institute of Health (NIH) had begun (by 1988) advising every American old enough to walk to restrict fat intake, and the president of the American Heart Association (AHA) had told Time magazine that if everyone went along, “we will have (atherosclerosis) conquered” by the year 2000. The Surgeon General’s Office itself had just published its 700-page landmark “Report on Nutrition and Health,” declaring fat the single most unwholesome component of the American diet.”

Such recommendations have resulted in a whole industry devoted to developing low-fat food-like substances which the public has perceived as healthier than the natural high fat original foods. Arguably, adoption of highly processed low-fat foods, which usually increase palatability by adding refined carbohydrates , sugar, or high-fructose corn syrup have contributed to America’s obesity epidemic. This, in turn through increasing obesity-associated diabetes, hypertension, and abnormal lipid profiles could have the unintended consequence of increasing heart disease.

The major focus of low-fat dietary recommendations has been to lower red meat consumption due to the high levels of saturated fat found in pork and beef. However, despite having a significantly different saturated fat composition, dairy products have been tarred with the same brush, so to speak. This has progressed to the point where, if one enters a frozen yogurt establishment (these businesses have proliferated at an alarming rate in the last few years) it is virtually impossible to find a full fat formulation of yogurt. Prominently featured are the words “no-fat” or “low-fat” with the implication that this is healthy for you. Instead of the natural fat of dairy , you have now been convinced to eat a form of dairy that has been highly processed, depleted of most nutrients and full of sugar and unrefined carbohydrates. To make up for the fat calories which might have left you more satiated without sharp peaks in blood glucose, you can substitute a whole panoply of sugary materials, chocolate, candies, or fruit.

It turns out that when the best epidemiological studies are examined in this area, the evidence suggests a protective effect of dairy on heart disease risk. Dr. Peter Elwood, a highly respected epidemiologist at the University of Wales, has consistently pointed this out based on his and other researchers’ studies.
To quote Elwood, the best epidemiological studies are “prospective cohort studies, based on data for individual subjects within a single community, with detailed attention given to confounding” variables. Such studies “give a much better basis for the examination of independent associations between food items and disease incidence than studies based on either ecological data or relationships with risk factors.”

In 2004, Elwood published a review of such studies which was published in the European Journal of Clinical nutrition. He found 10 studies worthy of inclusion. All but one study suggested that milk protects against heart disease. Those subjects consuming the most milk were less likely to have a heart attack or stroke than those consuming no milk. The relative risk for high volume milk drinkers versus those drinking no milk for “ischaemic heart disease” (this refers to coronary artery disease , the major cause of heart attacks) was 0.87. In other words, if you drank a lot of milk you were 13% less likely to have heart disease than if you drank none.

Elwood’s original research on this was called the Caerphilly Prospective Study. Between 1979 and 1983, 2500 men completed a food frequency questionnaire. During the following 21 years, the relative risk in men who drank more than a pint of milk per day, compared with the risk in men who drank no milk was 0.66 for ischemic heart disease and 0.84 for ischaemic stroke. In other words, high milk drinkers were 34% less likely to develop coronary heart disease, the major cause heart attacks.

All the studies reviewed were set up at times when reduced-fat milk was unavailable or scarce therefore the conclusion from the best available evidence in 2004 should have been that full fat dairy lowers your risk of heart attack and stroke.

For both the general public and for my cardiac patients I, therefore, differ strongly in my advice regarding dairy consumption from most published dietary guidelines. Keeping in mind that “all things in moderation” applies just as much in this area as any other, I advise full fat dairy consumption. This means that they can consume butter, milk, full-fat cheese and yogurt. I strongly advise utilizing dairy that comes from grass-fed , pasture-raised cows for reasons I will examine in subsequent posts. Each of these dairy products has a different fatty acid profile and therefore, likely a different effect on cholesterol profiles. Butter, in particular, may warrant separating out from the other dairy products because it is a very highly concentrated fat. However, since reviewing the published data on butter consumption and cardiovascular disease, I have personally gone back to fairly liberally applying butter (again, hopefully from grass-fed, pasture-raised cows) to a lot of my foods because there are few data suggesting that butter raises my risk of cardiovascular disease and the stuff tastes awesome.

Does Eating High-Fat Dairy Cause Heart Disease or Obesity

Dietary guidelines recommend the consumption of milk and dairy products as an important part of a healthy, well-balanced diet The 2010 USDA Guidelines state:
“Milk and milk products contribute many nutrients, such as calcium, vitamin D (for products fortified with vita- min D), and potassium, to the diet. Moderate evidence shows that intake of milk and milk products is linked to improved bone health, especially in children and adolescents. Moderate evidence also indicates that intake of milk and milk products is associated with a reduced risk of cardiovascular disease and type 2 diabetes and with lower blood pressure in adults.”

However, dairy fat has been portrayed as the unhealthy component of milk and dairy products, largely because it is energy dense and a rich source of saturated fatty acids . Therefore, typical dietary advice recommends fat-reduced milk and dairy products.

Shockingly, and despite expert and government-backed recommendations, the advice to change to fat-reduced or skim milk and dairy products is not supported by any prospective scientific studies.

The main reason cited for the recommendations is that the consumption of saturated fatty acids is related to an increase in total cholesterol which in turn has been related to increased coronary heart disease-the major cause of heart attacks. As we discuss this topic more, we will discover that this logic is flawed because 1) saturated fats are a diverse family of compounds with varying effects on the cholesterol profile and 2) the cholesterol profile itself is incredibly complex and simple measurements of “bad” (HDL) and “good” (LDL) cholesterol alone probably don’t tell us enough about the risk of heart disease .

Partially as a result of these guidelines, the pattern of dairy fat intake has changed considerably in the last 40 years, a time frame during which the modern obesity epidemic has developed in the United States Butter consumption has dropped considerably and low fat milk has supplanted full fat milk as the preferred product. In parallel, dairy fat consumption from other, possibly less healthy sources such as prepared foods, pizza, industrially produced margarine.

When epidemiologists have scientifically reviewed the relationship between high fat dairy consumption and heart disease or obesity, almost invariably they have found an inverse relationship. That is, the more dairy consumed, the lower the risk of heart disease and the less obesity.

In subsequent posts we’ll look in more detail at the evidence supporting dairy consumption in reducing heart disease and obesity.

Unbiased, evidence-based discussion of the effects of diet, drugs, and procedures on heart disease

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