Do Omega-3s Reduce Heart Disease Risk

Written by Dr. Steve Chaney on . Posted in Omega-3s and Heart Disease

Omega-3 Confusion

Author: Dr. Stephen Chaney

 This article includes updates as of October 2, 2018.  First, here is the earlier information.

do omega 3s reduce heart disease risk confusionDo omega-3s reduce heart disease risk?

Perhaps there is nothing more controversial in nutrition today than omega-3 fatty acids and heart disease risk. It is so confusing. One day you are told they reduce heart disease risk. The next day you are told they are worthless.

The controversy around omega-3s and heart disease risk is part of the larger controversy around supplementation. It is omega-3 supplements that are controversial, not omega-3-rich fish. Of course, that completely ignores the fact that many omega-3-rich fish are contaminated with PCBs and/or heavy metals.

Why is omega-3 supplementation so controversial? The problem is that proponents of omega-3 supplementation often seize on a single study as “proof” that everyone should supplement with omega-3s.  Opponents of omega-3 supplementation take the opposite approach. They pick studies showing that not everyone benefits from omega-3 supplementation as “proof” that nobody benefits. As usual, the truth is in between.

I have a section in my book, “Slaying The Food Myths,”  called “None of Us Are Average.” In that section I point out that clinical studies report the average results of everyone in the study, but nobody in the study was average.

For example, let’s say the study reported that (on average) there was no heart health benefit from omega-3 supplementation. That is what makes the headlines. That is what opponents of omega-3 supplementation cite as “proof” omega-3 supplementation doesn’t work.

However, some of the people in the study may have benefited from omega-3 supplementation, while others did not. Thus, the important question is not “Does everyone benefit from omega-3 supplementation?” It is “Who benefits from omega-3 supplementation?” and “Why do the results vary so much from study to study?”

Omega-3 Confusion

do omega 3s reduce heart disease risk rolesI have a chapter in my book called “What Role Does Supplementation Play?” which helps put this omega-3 controversy into perspective. I created the graphic on the left to answer the question “Who needs supplementation?”

The concept is simple. Poor diet, increased need, genetic predisposition, and pre-existing disease all increase the likelihood that supplementation will be beneficial. However, the benefit will be most obvious in the center of the diagram where two or more of these factors overlap.

Let’s take this concept and apply it to studies of omega-3 fatty acids and heart disease risk.  In particular, let’s use this concept to understand what I call “omega-3 confusion” – why some studies give negative results and others give positive results:

Poor Diet: Again, the concept is simple. You are most likely to see a benefit of omega-3 supplementation when the dietary intake of omega-3 fatty acids is low. Put another way, if the subjects in a study are already getting plenty of omega-3s from their diet, supplementing with omega-3s is unlikely to provide any benefit.

Until recently, dietary surveys were the standard method for assessing dietary omega-3 intake. However, dietary surveys can be inaccurate. The best of recent studies, measure the omega-3 levels in cellular membranes. The omega-3 levels at the beginning of the study reflect your diet. The omega-3 levels at the end of the study reflect how effective supplementation was at improving your omega-3 status. In short, this is the gold standard for omega-3 clinical studies. Subjects can lie about how many omega-3-rich foods they eat and whether they take their supplements, but the omega-3 levels in their cell membranes reveal the truth.

When you read the methods section, it turns out that most negative studies did not ask how much omega-3s their subjects were getting from their diet. Almost none of the negative studies measured omega-3 levels in cell membranes.

Increased Need: In terms of heart disease, we can think increased need as the presence of risk factors for heart disease such as:

  • Age
  • Obesity
  • Inactivity
  • Elevated cholesterol or triglycerides
  • Dietary factors like saturated fats and/or sugar and refined carbohydrates
  • Smoking

What does this mean in terms of clinical studies?

  • Studies in which most of the subjects have a poor diet, are over 65, and have multiple risk factors for heart disease are more likely to show a beneficial effect of omega-3s on heart disease risk.
  • Studies in which most of the subjects are young and healthy are unlikely to show a measurable benefit of omega-3s on heart disease risk. You would need to follow this population group 20, 30, or 40 years to demonstrate a benefit.

Genetic Predisposition: There is a lot we don’t know about genetic predisposition for heart disease. The only exception is family history. If you do omega 3s reduce heart disease risk geneticshave a family history of early heart disease, you can be pretty certain you are at high risk for heart disease. As you might suspect:

  • Studies focused on populations with genetic predisposition to heart disease are more likely to show a benefit of omega-3 supplementation.
  • Studies that just look at the general population without consideration of genetic predisposition to heart disease are less likely to show a benefit of omega-3 supplementation.

Disease: Diseases like diabetes and high blood pressure increase heart disease risk. And, of course, pre-existing heart disease, especially a recent heart attack, dramatically increase the risk of a subsequent heart attack or stroke. Studies focusing on subjects with diabetes have been inconsistent. However, studies focusing on patients with pre-existing heart disease are more clear-cut:

  • Studies focused on populations with pre-existing heart disease and/or a recent heart attack are more likely to show a benefit of omega-3 supplementation.
  • Studies that just look at the general population without consideration of genetic predisposition to heart disease are less likely to show a benefit of omega-3 supplementation.

Interestingly, the situation is very similar with statin drugs. As I reported in a recent issue  of “Health Tips From the Professor” on cholesterol lowering drugs, studies done with patients who had recently had a heart attack show a clear benefit of statin drugs, while studies with the general population show little or no benefit of statin drugs.

One More Factor: There is one more confounding factor that is somewhat unique to the omega-3-heart disease studies and, therefore, not included in the figure at the beginning of this section. Ethical considerations dictate that the placebo group in a double-blind, placebo controlled clinical study receive the “standard of care” for that disease. In the case of heart disease, the standard of care is 4-5 drugs which provide most of the same benefits as omega-3 fatty acids (although with many more side effects).

Thus, these studies are no longer asking whether omega-3s reduce heart disease risk. They are asking whether omega-3s have any additional benefits for heart disease patients already on 4-5 drugs. I have discussed this in more detail in a previous issue of “Health Tips From the Professor” on omega-3 and heart disease.

do omega 3s reduce heart disease risk conflicting studiesWhy Are Omega-3 Studies Conflicting? In summary, the likelihood that clinical studies show a beneficial effect of omega-3 fatty acids on heart disease risk is highly dependent on study design and the population group included in the study. Many of the studies currently in the scientific literature are flawed in one way or another. Once you understand that, it is obvious why there are so many conflicting studies in the literature.

Unfortunately, meta-analyses that combine data from many studies are no better than the individual studies they include in the analysis. It is the old “Garbage in – garbage out” principle.

What Does An Ideal Study Look Like? In my opinion, an ideal study to evaluate the effect of omega-3s on heart disease risk should (at minimum):

  • Determine omega-3 levels in cellular membranes as a measure of omega-3 status (dietary intake of omega-3s plus their utilization by the body). The percentage of omega-3 fatty acids in cell membranes is referred to as Omega-3 Index. Based on previous studies (W.S. Harris et al, Atherosclerosis, 262: 51-54, 2017, most experts consider an Omega-3 Index of 4% to be low and an Omega-3 Index of 8% to be optimal.
  • Focus on a population group at high risk for heart disease or include enough subjects in the study so that you can determine the effect of omega-3s on high risk subgroups.
  • Measure cardiovascular outcomes (heart attack, stroke, cardiovascular deaths, etc.).
  • Perform the study long enough so that you can accumulate a significant number of cardiovascular events.
  • Include enough subjects for a statistically significant conclusion.

Do Omega-3s Reduce Heart Disease Risk?

do omega 3s reduce heart disease riskMost of you have probably heard of the Framingham Heart Study. It was started in 1941 with a large group of residents of Framingham Massachusetts and surrounding areas. The data from this study over the years has shaped much of what we know about cardiovascular risk factors. The original participants have passed on, but the study has continued with their offspring, now in their 60s.

A recent study (W. H. Harris et al, Journal of Clinical Lipidology, doi: 10.1016/j.jacl.2018.02.010 ) with 2500 subjects in the Offspring Cohort of the Framingham Heart Study incorporates many of characteristics of a good omega-3 clinical study.

  • The average age of the subjects was 66. While none of the subjects enrolled in the study had been diagnosed with heart disease at the time the study began, this is a high-risk population. At this age a significant percentage of them would be expected to develop heart disease over the next few years.
  • The subjects did have other risk factors for heart disease. 13% of them had diabetes, 44% had high blood pressure, and 40% of them were on cholesterol medication. However, those risk factors were corrected for in the data analysis, so they did not influence the results.
  • The Omega-3 Index was measured in their red blood cell membranes at the beginning of the study.
  • The study was long enough (7.3 years) for cardiovascular disease to develop.

When they compared subjects with the highest Omega-3 Index (>6.8%) with those with the those with the lowest Omega-3 Index (<4.2%):

  • Death from all causes was reduced by 34%
  • Incident cardiovascular disease was reduced by 39% (Remember that none of the subjects had been diagnosed with heart disease at the beginning of the study. This terminology simply means that they received a new diagnosis of heart disease during the study.)
  • Cardiovascular events (primarily heart attacks) were reduced by 42%
  • Strokes were reduced by 55%.

There were two other interesting observations from the study:

  • There was no correlation between serum cholesterol levels and heart disease in this study.
  • The authors estimated that it would require an extra 1300 mg of omega-3s/day, either from a serving of salmon or from fish oil supplements, to bring the membrane Omega-3 Index from the lowest level in this study to an optimal level.

The authors cited three other recent studies performed in a similar manner that have come to essentially the same conclusion. These studies are not perfect. They are all association studies, so they do not prove cause and effect.

However, the authors concluded that Omega-3 Index should be measured routinely as a risk factor for heart disease and should be corrected if it is low.

The Bottom Line:

Perhaps there is nothing more controversial in nutrition today than omega-3 fatty acids and heart disease risk. It is so confusing. One day you are told they reduce heart disease risk. The next day you are told they are worthless.  I have discussed the reasons for the conflicting results and the resulting omega-3 confusion in the article above.

I shared a recent study that escapes many of the pitfalls of previous studies because it measures the Omega-3 Index of red blood cells as an indication of omega-3 status.

When the study compared subjects with the highest Omega-3 Index (>6.8%) with those with the those with the lowest Omega-3 Index (<4.2%):

  • Death from all causes was reduced by 34%
  • Incident cardiovascular disease was reduced by 39% (Remember that none of the subjects had been diagnosed with heart disease at the beginning of the study. This terminology simply means that they received a new diagnosis of heart disease during the study.)
  • Cardiovascular events (primarily heart attacks) were reduced by 42%
  • Strokes were reduced by 55%.

There were two other interesting observations from the study:

  • There was no correlation between serum cholesterol levels and heart disease in this study.
  • The authors estimated that it would require an extra 1300 mg of omega-3s/day, either from a serving of salmon or from fish oil supplements, to bring the membrane Omega-3 Index from the lowest level in this study to an optimal level.

The authors concluded that Omega-3 Index should be measured routinely as a risk factor for heart disease and should be corrected if it is low.

 

Are Omega-3s Worthless?

omega 3 and heart disease supplementsRecommendations from the medical industry changes often.  The following updates are in response to some of those changes concerning omega-3 and heart disease.  These updates were added on October 2, 2018.

The internet is abuzz with headlines saying things such as “Omega-3 Supplements Don’t Protect Against Heart Disease” and “Forget Omega-3s”. Are those headlines true? Should we throw our omega-3 supplements in the trash?

If the recent headlines are true, it is confusing, to say the least. In the late 90s and early 2000s we were being told of clinical studies showing that omega-3s reduced the risk of heart attack and stroke. At that time the American Heart Association was recommending omega-3 supplements for patients at high risk of heart attack or stroke. What has changed?

It turns out that a lot has changed. The design of clinical studies has changed dramatically in the past 10-15 years. I have covered the changing omega-3 story in detail in my upcoming book “Slaying The Supplement Myths.” Let me just summarize a few key differences between the year 2000 and today.

  • The definition of “high risk of heart attack and stroke” has changed dramatically since 2000. Clinical studies today include subjects who have a much lower risk of heart attack and stroke. That makes it more difficult to see any benefits of omega-3s.
  • Most studies do not measure the omega-3 status of their subjects. That means they do not know whether their patients were omega-3 deficient at the beginning of the study. It also means they have no objective measure of how faithfully the subjects took their omega-3 capsules.
  • We are asking a totally different question today than we were in the year 2000. It is considered unethical to withhold “standard medical care” from the control group. In 2000 the standard of care was one or two heart medications and often did not include a statin. Back then we were asking “Do omega-3s reduce the risk of heart attack and stroke?” Today, the standard of care is 3-5 heart medications, each of which provides some of the same benefits as omega-3s. Today we are asking the question “Do omega-3s provide any additional benefit for people who are already taking 3-5 heart medications?”

Let me start by analyzing a recent study that illustrates these points perfectly.

How Was The Study Done?

omega 3 and heart disease studyOn the surface the study appeared to be a well-designed study. The study (The ASCEND Study Collaborative Group, New England Journal Of Medicine, DOI: 10.1056/NEJMoa1804989, 2018 ) was conducted by scientists from the University of Oxford. They used a national diabetes registry and contacted general practitioners from all over England to identify 15,480 patients who had diabetes, but no evidence of heart disease and were willing to participate in the study. Participants were at least 40 (average age 63) and 60% male.

The participants were mailed a six month’s supply of capsules containing either 1 gram of omega-3s or olive oil as a placebo. Each 6 months the participants were mailed a questionnaire to report on whether they took the capsule daily and whether they had any adverse side effects. If they returned the questionnaire, they were given another 6 month’s supply of omega-3s or placebo. The patients were followed for an average of 7.4 years and “adverse vascular events” (simple definition: non-fatal and fatal heart attack or stroke) were recorded.

 

Omega-3 and Heart Disease?

omega 3 and heart disease no affectsThe authors of the study reported:

  • Omega-3 supplementation had no significant effect on either serious vascular events or death from any cause.

The authors concluded “These findings, together with results of earlier randomized trials involving patients with and without diabetes, do not support the current recommendations for routine dietary supplementation with omega-3 fatty acids to prevent vascular events.”

On the surface, this appears to be a strong study and the results were conclusive. What could go wrong? The answer is “Plenty.”

What Are The Weaknesses Of The Study?

omega 3 and heart disease flawsThe study contains multiple weaknesses that have been ignored by the medical community and the press.

Omega-3 Supplements Reduced Vascular Deaths In This Study. To begin with, the study showed that omega-3 supplementation reduced vascular deaths (simple definition: fatal heart attacks and stroke) by 18%. That observation was reported as a single sentence in the Results section of the paper but did not appear in either the Discussion or Abstract. It was also not reported in any of the media reports telling you that omega-3s are worthless. Perhaps it did not match the preconceived beliefs of the authors.

This Study Was Not Really Looking At High Risk Patients. The studies in the late 90’s and early 2000’s showing a significant effect of omega-3s on heart attack risk were done with truly high-risk patients. For example, the best of these studies looked at the effect of omega-3 supplementation in patients who had suffered a heart attack in the past 6 months. Those patients were at high risk of a second heart attack in the next 6-12 months. They were in imminent danger.

This study looked at patients with diabetes. They have a 2 to 3-fold risk of heart attack or stroke over the next decade. That’s a big difference. In addition, this study only looked at patients with diabetes AND no evidence of heart disease. Their risk of heart attack and stroke is substantially less. In fact, if you look at the data in the study, 83% of the participants in their study were at low to moderate risk of heart disease. Only 17% were at high risk.

To put that into perspective, it has only been possible to prove the effectiveness of statins when they are tested in patients who have already suffered a heart attack. In low risk populations, their benefit is almost negligible. You will find details about those studies in my new book “Slaying The Supplement Myths.

If you can’t prove statins are effective in low risk populations, why would you expect to be able to show omega-3s are effective in low risk populations.

omega 3 and heart disease optimumThe Subjects Were Already Getting Near Optimum Amounts of Omega-3s From Their Diet. The study analyzed the omega-3 index (a measure of omega-3 status) from a randomly selected subset of participants at the beginning and end of the study. They reported that the omega-3 index in their study participants increased from 7.1% at the beginning to 9.1% at the end, a 32% increase. They considered that to be a good thing because it showed that their participants were taking the omega-3 supplements faithfully.

However, let’s put that into perspective. An omega-3 index of 4% is associated with a high risk of heart disease. An omega-3 index of 8% is associated with a low risk of heart disease. It is considered optimum. With an omega-3 index of 7.1% at the beginning of the study, the subjects already had near optimum omega-3 status before the study even began.

If the subjects were already at near optimum omega-3 status, why would you expect additional omega-3 supplementation to be beneficial?

The Subjects Were On 3-5 Heart Medications. To discover this, you had to dig a little.  Something only a science-wonk like me is willing to do. The Results section reported that 35% of the subjects were taking aspirin and 75% were on a statin. You have to go to the Supplementary Data online to discover that most of the subjects were on 3-5 heart medications in addition to 1 or 2 medications for diabetes. That is somewhat curious because nobody in the study had any detectable cardiovascular disease.

To understand the significance of this observation, we look at what the drugs do. Aspirin prevents blood clot formation in our arteries, which is one of the main benefits of omega-3s. For reasons nobody understands, statins decrease inflammation, which is another major benefit of omega-3s. Most of the subjects were also taking a medicine to decrease blood pressure, another major benefit of omega-3s.

If subjects are already on 3-5 heart medications that duplicate the benefits of omega-3s, why would you expect omega-3 supplementation to be beneficial?

As I said before, we are now asking a totally different question than we were in the studies performed in the late 90s and early 2000s. Back then we were asking whether omega-3s reduced the risk of heart disease. Today we are asking whether omega-3s have any additional benefits for someone who is already on 3-5 heart medications. That question may be of interest to your doctors, but it is probably not the question most of you are interested in.

Even worse, every one of those drugs has documented side effects. For example, the same group that published this paper also examined the role of aspirin in reducing heart attacks in the same patient population and concluded that the befits of aspirin were “largely counterbalanced by the bleeding hazard [caused by aspirin use],” (The ASCEND Study Collaborative Group, New England Journal Of Medicine, DOI: 10.1056/NEJMoa1804988, 2018).  In contrast, they found no side effects in the group receiving 1 gram/day of omega-3s.

Garbage In Again, Garbage Out Again

do omega 3s reduce heart disease risk conflicting studiesTwo recent meta-analyses (T Aung et al,  JAMA Cardiology 3: 225-234, 2018  and Cochrane Database of Systematic Reviews ) have analyzed all the recent placebo-controlled studies and have concluded that omega-3s are of little or no use for reducing heart disease risk. However, those meta-analyses both suffered from what, in the computer programming world, is called “Garbage in. Garbage out.”

The meta-analyses included the studies from the late 90s and early 2000s, but the positive data from those studies was swamped out by all the recent negative studies, most of which suffered from the same flaws as the study I reviewed above. This is the “Achilles’ Heel” of meta-analysis. If they include flawed studies in their analysis, their conclusions will also be flawed. What the recent studies do tell us is that omega-3s are of little additional benefit if you are already taking multiple heart medications.

 

Don’t Throw The Baby Out With The Bathwater

The next time you visit your doctor you are likely to be told: “The evidence is in. We know that omega-3s don’t reduce the risk of heart attack.” Now you know the truth. What we can definitively conclude is that omega-3s offer little additional benefit if you are already taking multiple heart medications. As I said before, that question may be of interest to your doctor but is probably not the question you had in mind.

omega 3 and heart disease reduce blood pressureUnfortunately, because of the way clinical studies of omega-3 supplementation and heart disease risk are currently conducted, we may never have a definitive answer to whether omega-3s reduce heart disease risk for those of us who aren’t taking heart medications.

However, even if there is some controversy about omega-3s and heart disease risk, there are multiple other reasons for making sure that your omega-3 status is optimum. For example:

  • We know that omega-3s reduce triglycerides. This is non-controversial.
  • There is excellent evidence that omega-3s improve arterial health and reduce blood pressure.
  • There is good evidence that omega-3s reduce inflammation.

If they also reduce heart disease risk, consider that to be a side benefit.

The Bottom Line

A recent study has reported that that omega-3s do not reduce the risk of heart attack and stroke. However, the study suffered from multiple flaws.

  • Omega-3s reduced the risk of cardiovascular deaths in the study by 18%. That never got reported by the media.
  • The study was looking at subjects at relatively low risk of heart disease.

If you can’t even prove statins are effective in low risk populations, why would you expect to be able to show omega-3s are effective in low risk populations.

  • The subjects had near optimum omega-3 status before the study even began.

If the subjects were already at near optimum omega-3 status, why would you expect additional omega-3 supplementation to be beneficial?

  • The subjects were on 3-5 heart medications that provided many of the same benefits as omega-3s, but with side effects.

If subjects are already on 3-5 heart medications that duplicate the benefits of omega-3s, why would you expect omega-3 supplementation to be beneficial?

Two recent meta-analyses also concluded that omega-3s do not reduce the risk of heart disease. However, most of the studies in those meta-analyses suffered from the same flaws as the study I reviewed in this article. The meta-analyses are an excellent example of what computer programmers refer to as “Garbage in. Garbage out.”

The next time you visit your doctor you are likely to be told: “The evidence is in. We know that omega-3s don’t reduce the risk of heart attack.” Now you know the truth. What we can definitively conclude is that omega-3s offer little additional benefit if you are already taking multiple heart medications. That question may be of interest to your doctor, but that is probably not the question you had in mind.

Unfortunately, because of the way that clinical studies of omega-3 supplementation and heart disease risk are currently conducted, we may never have a definitive answer to whether omega-3s reduce heart disease risk for those of us who aren’t taking heart medications.

However, even if there is some controversy about omega-3s and heart disease risk, there are multiple other reasons for making sure that your omega-3 status is optimum. For example:

  • We know that omega-3s reduce triglycerides. This is non-controversial.
  • There is excellent evidence that omega-3s improve arterial health and reduce blood pressure.
  • There is good evidence that omega-3s reduce inflammation.

If they also reduce heart disease risk, consider that to be a side benefit.

For more details, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Comments (7)

  • EROCA

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    A share button would make it easier to show others.

    Reply

    • Dr. Steve Chaney

      |

      Dear Eroca,

      Good idea, but not sure how to make that happen. I will have to check with my IT guru.

      Dr. Chaney

      Reply

  • Joann Miley

    |

    This information really told the truth about omega 3’s and I totally feel that was the best explanation I have ever read.

    I sincerely thank you for your expertise and sharing this valuable information to us. I firmly believe the omega 3’s have been a benefit to me. Thank you, Keep up your excellent work.
    Joann Miley

    Reply

  • Joann Miley

    |

    thank you

    Reply

  • William Byrne

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    GREAT N/L information….all good stuff to keep us healthy and going. personally I love our “heart healthy” products…..especially now at almost 80, indeed I need a strong heart….one that can carry me through an intense match of tennis….one that can sustain my interest and need to exercise…or just a heart strong enough to take on the daily stresses of life in general. So yes…I LOVE THE OMEGAS as well as any Shaklee preparations related to HEART HEALTH.

    Reply

  • William Byrne

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    THE OMEGAS…WHY A LL THE CONTROVERSY??? ITS PROVEN ISN’T IT? INDEED QUALITY.. AND .HARVESTING OF THE CLEAN FISH ALL PLAY AN IMPORTANT ROLE IN RESULTS (OR NOT) WE RECEIVE FROM SUPPLEMENTING OUR DIET WITH FISH OIL. PERSONALLY I AM ALL FOR IT ESPECIALLY WHEN MY DOCTOR SAYS I AM IN GOOD SHAPE AND THAT I MAKE GOOD BLOOD. A LARGE PART, I BELIEVE, DUE TO CONSISTENCY BOTH WITH STRENGTH / AEROBIC EXERCISE AS WELL AS TAKING A GOOD QUALITY PURE OMEGA 3
    FOR MANY YEARS. RARELY MISSING MY OPPORTUNITY TO CONTINUE TO BUILD NEW HEART HEALTH. EVEN AT THE RIPE OLD AGE OF 79.

    Reply

    • Dr. Steve Chaney

      |

      Dear William,

      Yes. Omega-3s are part of the puzzle, but so is exercise and a good diet. Keep up the good work!

      Dr. Chaney

      Reply

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Latest Article

Best Diet For Heart Disease Prevention

Posted July 9, 2019 by Dr. Steve Chaney

Are The American Heart Association’s Recommendations Correct?

Author: Dr. Stephen Chaney

 

What is the best diet for heart disease prevention? 

diet for heart disease preventionHeart disease is a killer. It continues to be the leading cause of death – both worldwide and in industrialized countries like the United States and the European Union. When we look at heart disease trends, it is a good news – bad news situation.

  • The good news is that heart disease deaths are continuing to decline in adults over 70.
  • The decline among senior citizens is attributed to improved treatment of heart disease and more seniors following heart-healthy diets.
  • The bad news is that heart disease deaths are starting to increase in younger adults, something I reported in an earlier issue, Heart Attacks Increasing in Young Women of “Health Tips From the Professor.”
  • The reason for the rise in heart disease deaths in young people is less clear. However, the obesity epidemic, junk and convenience foods, and the popularity of fad diets all likely play a role.

Everyone has a magic diet for reducing heart disease risk. The American Heart Association tells us to avoid fats, especially saturated fats. Vegans tell us to avoid animal protein. Paleo and keto enthusiasts tell us carbs are the problem. Who is correct?

Of course, we don’t eat fats, carbohydrates, or proteins. We eat foods. That is why a recent study (T Meier et al, European Journal of Epidemiology, 34: 37-45, 2019) is so important. It reported which foods increase and which decrease the risk of premature heart disease deaths.

How Was The Study Done?

diet for heart disease prevention studyThe authors of the current study analyzed data from the “Global Burden of Diseases (GBD) Study”, a major world-wide effort designed to estimate the portions of deaths caused by various risk factors.

The current study focused on the impact of 12 dietary risk factors on heart disease deaths between 1990 and 2016 for 51 countries in four regions (Western Europe, Central Europe, Eastern Europe, and Central Asia).

The dietary risk factors were:

  • Diets low in fiber, fruits, vegetables, legumes, nuts and seeds, polyunsaturated fatty acids, omega-3 fatty acids, and whole grains.
  • Diets high in sodium, processed meats, sugar-sweetened beverages, and trans fatty acids.

Saturated fat and meat were not explicitly included in the GBS Study data. However, diets low in polyunsaturated fats and omega-3 fats are likely high in saturated fats. Similarly, diets low in fruits, vegetables, whole grains, and legumes are likely higher in meats. The study also did not include dairy, and some recent studies suggest that some dairy foods may decrease heart disease risk.

For simplicity I will only consider the findings from Western Europe because their diet and heart disease death trends are similar to those in the United States.

 

Best Diet for Heart Disease Prevention?

plant-based diet bestThe study found that in 2016 (the last year for which data were available):

  • Dietary risk factors were responsible for 49.2% of heart disease deaths.
  • 6% of all diet-related heart disease deaths occurred in adults younger than 70, and that percentage has been increasing in recent years.

When they looked at the contribution of individual foods to diet related heart disease deaths, the percentages were:

  • Diets low in whole grains = 20.4%
  • Diets low in nuts and seeds = 16.2%
  • Diets low in fruits = 12.5%
  • Diets high in sodium = 12.0%
  • Diets low in omega-3s = 10.8%
  • strong heartDiets low in vegetables = 9.0%
  • Diets low in legumes = 7.0%
  • Diets low in fiber = 5.7%
  • Diets low in polyunsaturated fats = 3.7%
  • Diets high in processed meats = 1.6%
  • Diets high in trans fatty acids = 0.8%
  • Diets high in sugar-sweetened beverages = 0.1%

So, what is the best diet for heart disease prevention?

In short, this study concluded:

  • A primarily plant-based diet is the best protection against premature death due to heart disease.
  • All plant-based food groups (whole grains, nuts and seeds, fruits, vegetables, and legumes) play an important role in reducing heart disease deaths.
  • Meat was not included in the analysis, but it is likely that most people’s diets in this region of the world contained some meat. The most likely take-away is that meat does not affect heart disease risk in the context of a primarily plant-based diet.
  • Dairy was not included in the analysis either, but some studies suggest dairy, particularly fermented dairy foods, reduce heart disease risk.
  • Finally, the study concluded: “Compared to other…modifiable risk factors (physical inactivity, drug and alcohol abuse, tobacco smoking, obesity, etc.), an altered diet is the most effective means of preventing premature deaths from cardiovascular disease in Western Europe.”

While every study has its weaknesses, this study is consistent with multiple previous studies showing that primarily plant-based diets are best for reducing heart disease risk. You will find a more complete discussion of these studies in my book “Slaying The Food Myths.”

 

Are the American Heart Association’s Recommendations Correct?

With this study’s results in mind we can now ask whether the recommendations of the American Heart Association and other popular diets are correct. Are they likely to reduce heart disease deaths?

  • The American Heart Association Recommends a dietary pattern that emphasizes a variety of fruits and vegetables, whole grains, nuts and legumes, skinless poultry and fish, and low-fat dairy products. This study supports those recommendations.
  • This study also supports the heart-health benefits of the Mediterranean and DASH diets.
  • Meat and dairy were not explicitly considered in this study. Thus, the results of this study are also consistent with vegan and semi-vegetarian diets.
  • However, low carb diets like Paleo and keto eliminate some of the key food groups (whole grains, fruits, and legumes) that appear to be essential for reducing heart disease risk. 40% of the heart-health benefits in this study came from those 3 food groups. Thus, this study does not support claims that those two diets are heart-healthy long term.

 

The Bottom Line

 

Everyone has a magic diet for reducing heart disease risk. The American Heart Association tells us to avoid fats, especially saturated fats. Vegans tell us to avoid animal protein. Paleo and keto enthusiasts tell us carbs are the problem. Who is correct?

A recent study provides some important clues. It looked at dietary patterns associated with reduced risk of premature death from heart disease in Western Europe. The study concluded:

  • A primarily plant-based diet is the best protection against premature death due to heart disease.
  • All plant-based food groups (whole grains, nuts and seeds, fruits, vegetables, and legumes) play an important role in reducing heart disease deaths.
  • Meat did not appear to affect heart disease risk in the context of a primarily plant-based diet.
  • Dairy was not included in the analysis, but some studies suggest dairy, particularly fermented dairy foods, reduce heart disease risk.
  • Finally, the study concluded: “Compared to other…modifiable risk factors (physical inactivity, drug and alcohol abuse, tobacco smoking, obesity, etc.), an altered diet is the most effective means of preventing premature deaths from cardiovascular disease.”

While every study has its weaknesses, this study is consistent with multiple previous studies showing that primarily plant-based diets are best for reducing heart disease risk. You will find a more complete discussion of these studies in my book “Slaying The Food Myths.”

With this study’s results in mind we can now ask whether the recommendations of the American Heart Association and other popular diets are correct. Are they likely to reduce heart disease deaths?

  • The American Heart Association Recommends a dietary pattern that emphasizes a variety of fruits and vegetables, whole grains, nuts and legumes, skinless poultry and fish, and low-fat dairy products. This study supports those recommendations.
  • This study also supports the heart-health benefits of the Mediterranean and DASH diets.
  • Meat and dairy were not explicitly considered in this study. Thus, the results of this study are also consistent with vegan and semi-vegetarian diets.
  • However, low carb diets like Paleo and keto eliminate some of the key food groups (whole grains, fruits, and legumes) that appear to be essential for reducing heart disease risk. 40% of the heart-health benefits in this study came from those 3 food groups. Thus, this study does not support claims that those two diets are heart-healthy long term.

For more details read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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