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

 

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.

 

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

    |

    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

Do Omega-3s Lower Blood Pressure in Young, Healthy Adults?

Posted August 14, 2018 by Dr. Steve Chaney

What Is The Omega-3 Index And Why Is It Important?

Author: Dr. Stephen Chaney

 

Do omega-3s lower blood pressure in healthy adults?

omega-3s lower blood pressure young adultsThe literature on the potential health benefits of omega-3s is very confusing. That’s because a lot of bad studies have been published. Many of them never determined the omega-3 status of their subjects prior to omega-3 supplementation. Others relied on dietary recalls of fish consumption, which can be inaccurate.

Fortunately, a much more accurate measure of omega-3 status has been developed and validated in recent years. It’s called the Omega-3 Index. Simply put, the Omega-3 Index is the percentage of EPA and DHA compared to 26 other fatty acids found in cellular membranes. Using modern technology, it can be determined from a single finger prick blood sample. It is a very accurate reflection of omega-3 intake relative to other fats in the diet over the past few months. More importantly, it is a measure of the omega-3 content of your cell membranes, which is a direct measure of your omega-3 nutritional status.

A recent extension of the Framingham Heart Study reported that participants with an Omega-3 Index >6.8% had a 39% lower risk of cardiovascular disease than those with an Omega-3 Index <4.2% (WS Harris et al, Journal of Clinical Lipidology, 12: 718-724, 2018 ). Although more work needs to be done, an Omega-3 Index of 4% or less is generally considered indicative of high cardiovascular risk, while 8% or better is considered indicative of low cardiovascular risk. For reference, the average American has an Omega-3 Index in the 4-5% range. In Japan, where fish consumption is much higher and cardiovascular risk much lower, the Omega-3 Index is in the 9-11% range.

Previous studies have suggested that omega-3 fatty acids lower blood pressure to a modest extent. Thus, it is not surprising that more recent studies have shown an inverse correlation between Omega-3 Index and blood pressure. However, those studies have been done with older populations, many of whom had already developed high blood pressure.

From a public health point of view, it is much more interesting to investigate whether it might be possible to prevent high blood pressure in older adults by optimizing omega-3 intake in a young, healthy population, most of whom had not yet developed high blood pressure. Unfortunately, there were no studies looking at that population. The current study was designed to fill that gap.

 

How Was The Study Done?

omega-3s lower blood pressure young healthy adultsThe current study (M.G. Filipovic et al, Journal of Hypertension, 36: 1548-1554, 2018 ) was based on data collected from 2036 healthy adults, aged 25-41, from Liechtenstein. They were participants in the GAPP (Genetic and Phenotypic Determinants of Blood Pressure) study. Participants were excluded from the study if they had been diagnosed with high blood pressure and were taking medication to lower their blood pressure. They were also excluded if they had heart disease, chronic kidney disease, other severe illnesses, obesity, sleep apnea, or daily use of non-steroidal anti-inflammatory medications.

Blood samples were collected at the time of their enrollment in the study and frozen for subsequent determination of Omega-3 Index. Blood pressure was also measured at their time of enrollment in two different ways. The first was a standard blood pressure measurement in a doctor’s office.

For the second measurement they were given a wearable blood pressure monitor that recorded their blood pressure over 24 hours every 15 minutes during the day and every 30 minutes while they were sleeping. This is considered more accurate than a resting blood pressure measurement in a doctor’s office because it records the variation in blood pressure, while you are sleeping, while you are exercising, and while you go about your everyday activities.

 

Do Omega-3s Lower Blood Pressure In Young, Healthy Adults?

omega-3s lower blood pressure young adults equipmentNone of the participants in the study had significantly elevated blood pressure. The mean systolic and diastolic office blood pressures were 120±13 and 78±9 respectively. The average Omega-3 Index in this population was 4.6%, which is similar to the average Omega-3 Index in the United States.

When they compared the group with the highest Omega-3 Index (average = 5.8%) with the group with the lowest Omega-3 Index (average = 4.6%):

  • The office measurement of systolic and diastolic blood pressure was decreased by 3.3% and 2.6% respectively
  • While those numbers appear small, the differences were highly significant.
  • The 24-hour blood pressure measurements showed a similar decrease.
  • Blood pressure measurements decreased linearly with increasing Omega-3 Index. [In studies of this kind, a linear dose-response is considered an internal validation of the differences observed between the group with the highest Omega-3 Index and the group with the lowest Omega-3 Index.]

The authors concluded: “A higher Omega-3 Index is associated with statistically significant, clinically relevant, lower systolic and diastolic blood pressure in normotensive, young and healthy individuals. Diets rich omega-3 fatty acids may be a strategy for primary prevention of hypertension.”

 

What Does This Mean For You?

omega-3s lower blood pressure young adults questionPerhaps I should first comment on the significance of the relatively small decrease in blood pressure observed in this study.

  • These were young adults, all of whom had normal or near normal blood pressure.
  • The difference in Omega-3 Index was rather small (5.8% to 4.6%). None of the participants in the study were at the 8% or above that is considered optimal.
  • Liechtenstein is a small country located between Switzerland and Spain. Fish consumption is low and omega-3 supplement consumption is rare.

Under these conditions, even a small, but statistically significant, decrease in blood pressure is remarkable.

We should think of this study as the start of the investigation of the relationship between omega-3 status and blood pressure. Its weakness is that it only shows an association between high Omega-3 Index and low blood pressure. It does not prove cause and effect.

Its strength is that it is consistent with many other studies showing omega-3 fatty acids lower blood pressure. Furthermore, it suggests that the effect of omega-3s on blood pressure may also be seen in young, healthy adults who have not yet developed high blood pressure.

Finally, the authors suggested that a diet rich in omega-3s might reduce the incidence of high blood pressure by slowing the age-related increase in blood pressure that most Americans experience. This idea is logical, but speculative at present.

However, the GAPP study is designed to provide the answer to that question. It is a long-term study with follow-up examinations scheduled every 3-5 years. It will be interesting to see whether the author’s prediction holds true, and a higher Omega-3 Index is associated with a slower increase in blood pressure as the participants age.

 

Why Is The Omega-3 Index Important?

 

The authors of this study said: “The Omega-3 Index is very robust to short-term intake of omega-3 fatty acids and reliably reflects an individual’s long-term omega-3 status and tissue omega-3 content. Therefore, the Omega-3 Index has the potential to become a cardiovascular risk factor as much as the HbA1c is for people with diabetes…” That is a bit of an overstatement. HbA1c is a measure of disease progression for diabetes because it is a direct measure of blood sugar control.

In contrast, Omega-3 Index is merely a risk factor for cardiovascular disease. However, if it is further validated by future studies, it is likely to be as important for predicting cardiovascular risk as are cholesterol levels and markers of inflammation.

However, to me the most important role of Omega-3 Index is in the design of future clinical studies. If anyone really wants to determine whether omega-3 supplementation reduces cardiovascular risk, high blood pressure, diabetes or any other health outcome they should:

  • Start with a population group with an Omega-3 Index in the deficient (4-5%) range.
  • Supplement with omega-3 fatty acids in a double blind, placebo-controlled manner.
  • Show that supplementation brought participants up to an optimal Omega-3 Index of 8% or greater.
  • Look at health outcomes such as heart attacks, cardiovascular deaths, hypertension, stroke, or depression.
  • Continue the study long enough for the beneficial effects of omega-3 supplementation to be measurable. For cardiovascular outcomes the American Heart Association has stated that at least two years are required to obtain meaningful results.

These are the kind of experiments that will be required to give definitive, reproducible results and resolve the confusion about the health effects of omega-3 fatty acids.

 

The Bottom Line

 

An accurate measure of omega-3 status has been developed and validated in recent years. It’s called the Omega-3 Index. Simply put, the Omega-3 Index is the percentage of EPA and DHA compared to 26 other fatty acids found in cellular membranes.

Although more work needs to be done, an Omega-3 Index of 4% or less is generally considered indicative of high cardiovascular risk while 8% or better is considered indicative of low cardiovascular risk.

Previous studies have shown an inverse correlation between Omega-3 Index and blood pressure. However, these studies have been done with older populations, many of whom had already developed high blood pressure.

From a public health point of view, it is much more interesting to investigate whether it might be possible to prevent high blood pressure in older adults by optimizing omega-3 intake in a young, healthy population, most of whom had not yet developed high blood pressure. Until now, there have been no studies looking at that population.

The study described in this article was designed to fill that gap. The participants in this study were ages 25-41, were healthy, and none of them had elevated blood pressure.

When the group with the highest Omega-3 Index (average = 5.8%) was compared with the group with the lowest Omega-3 Index (average = 4.6%):

  • Both systolic and diastolic blood pressure were decreased
  • Blood pressure measurements decreased linearly with increasing Omega-3 Index.

The authors concluded: “A higher Omega-3 Index is associated with statistically significant, clinically relevant, lower systolic and diastolic blood pressure in normotensive, young and healthy individuals. Diets rich omega-3 fatty acids may be a strategy for primary prevention of hypertension.”

Let me translate that last sentence into plain English for you. The authors were saying that optimizing omega-3 intake in young adults may slow the age-related increase in blood pressure and reduce the risk of them developing high blood pressure as they age. This may begin to answer the question “Do omega-3s lower blood pressure in young, healthy adults?”

Or even more simply put: Aging is inevitable. Becoming unhealthy is not.

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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