Omega-3 and Heart Disease Risk

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

Why Is There So Much Confusion About Omega-3 and Heart Disease Risk?

Author: Dr. Stephen Chaney

 

omega-3 heart diseaseConcerning omega-3 and heart disease, the pendulum keeps swinging. In the 1990’s several strong clinical studies showed that omega-3s reduced heart disease risk. In fact, a major clinical study in Italy, (Lancet 354: 447 – 455, 1999 , Circulation 105 : 1897 – 1903, 2002 ), found omega-3s to be just as effective as statin drugs for preventing heart attacks, but without any of the side effects of statins.

At that time, everyone was talking about the benefits of omega-3s in reducing heart disease risk. The American Heart Association recommended an intake of 500-1,000 mg/day of omega-3s for heart health. Some experts were recommending even more if you were at high risk of heart disease.

In the 2000’s the pendulum swung in the other direction. Several clinical studies found no benefit of omega-3s in reducing heart disease risk. Suddenly, experts were telling us that omega-3s were overrated. They were a waste of money. The American Heart Association kept their omega-3 recommendations for heart health, but put more emphasis on omega-3s for people with elevated triglycerides (where the benefits of omega-3s are non-controversial).

Suddenly regarding omega-3 and heart disease, the pendulum is swinging back again. A recent meta-analysis (Alexander et al, Mayo Clinic Proceedings, 92: 15-29, 2017) reported that omega-3s do appear to be beneficial at reducing heart disease risk. An editorial accompanying that article (O’Keefe et al, Mayo Clinic Proceedings, 92: 1-3, 2017) called the meta-analysis “the most comprehensive of its kind to date…” Those experts went on to say “…omega-3-fatty acid intake of at least 1 gram of EPA + DHA per day, either from seafood or supplementation (as recommended by the American Heart Association) continues to be a reasonable strategy.”

This was followed by publication of three clinical studies that came to essentially the same conclusion (Kieber et al, Atherosclerosis, 252: 175-181, 2016 ; Sala-Vila et al, Journal of the American Heart Association, In Press ; and Greene et al, American Journal of Cardiology, 117: 340-346, 2016 ).

Why is there so much confusion about omega-3 and heart disease? Let’s start by reviewing the recently published meta-analysis.

 

Do Omega-3s Lower Heart Disease Risk?

omega-3 lowers heart disease riskThis study (Alexander et al, Mayo Clinic Proceedings, 92: 15-29, 2017) combined the data from 18 randomized controlled trials with 93,000 patients and 16 prospective cohort studies with 732,000 patients. This was the largest meta-analysis on omega-3s and heart health performed to date. The results were as follows:

  • The combined data from the randomized controlled studies showed that omega-3 supplementation resulted in a non-significant 6% reduction in heart disease risk. This is similar to other recently published studies (more about that later).
  • However, when the investigators looked at high risk populations within the randomized controlled studies, the results were strikingly different.
    • In patients with elevated triglycerides, omega-3 supplementation caused a significant 16% reduction in heart disease risk.
    • In patients with elevated LDL cholesterol, omega-3 supplementation caused a significant 18% reduction in heart disease risk.
  • In addition, the combined data from the prospective cohort studies showed that omega-3 supplementation resulted in a significant 18% decrease in heart disease risk.

The authors concluded “[Our] results indicate that EPA + DHA may be associated with reducing heart disease risk, with greater benefits observed among higher-risk populations…”

 

Why Is There So Much Confusion About Omega-3s and Heart Disease Risk?

confusionThere are several major clinical studies in progress looking at the effect of omega-3s on heart health. Some experts predict that the confusion will be cleared up once they are published. I predict they will only add to the confusion. Let me explain why.

You’ve heard the old saying “Garbage in – garbage out.”  Proper design of clinical studies is essential. If a study is poorly designed, it provides incorrect information. When you analyze the previous clinical studies carefully, you find that many of them are flawed. Their results are, therefore, incorrect. My fear is that many of the ongoing clinical studies will contain the same flaws and will provide the same incorrect information.

Let’s look at the flaws, and why they provide incorrect information.

Flaw #1: Omega-3 supplementation will only be beneficial for people who are omega-3 deficient. The authors of the Mayo Clinic Proceedings editorial provided a useful analogy. They said: “Vitamin C bestows dramatic and lifesaving benefits to persons with scurvy, but is no better than placebo for persons who are replete with vitamin C.”

That means a well-designed study should measure omega-3 levels in red blood cells both prior to and at the end of the clinical study. The data analysis should focus on those individuals who started the study with low omega-3 status and whose omega-3 status improved by the end of the study. Unfortunately, few of the previously published studies have done that, and I am not confident that the ongoing studies have incorporated that into their experimental design.

Flaw #2: Omega-3 supplementation will be of most benefit for those people who are at highest risk for heart disease. This has been a recurrent pattern in the literature. Many of the clinical studies focusing on high-risk individuals have shown a beneficial effect of omega-3 supplementation on heart disease risk. Most of the studies focusing on the general population (most of which are of low risk for heart disease) have failed to show a benefit of omega-3 supplementation. The current meta-analysis is no exception. When they looked at the general population, there was a non-significant reduction in heart disease risk. However, when they looked at high-risk populations the beneficial effect of omega-3s was highly significant.

I can’t predict how the ongoing studies will analyze their data. If they focus on high-risk groups they are more likely to report a beneficial effect of omega-3s on heart health. If they only report on the results with the general population, they are likely to conclude that omega-3s are ineffective.

I do need to make an important distinction here. The inability to demonstrate a beneficial effect of omega-3 supplementation in the general population does not mean that there is no effect. It turns out to be incredibly difficult to demonstrate a beneficial effect of any intervention, including statins , in a healthy, low-risk population. Because of that, we may never know for sure about the relationship between omega-3 and heart disease. Do omega-3s reduce heart disease risk for the young and healthy. At the end of the day, you will need to make your own decision about whether omega-3s make sense to you.

omega-3 supplementationFlaw #3: Heart medications mask the beneficial effects of omega-3 supplementation. When the public hears about the results of a randomized controlled study they assume that the placebo group received no treatment and the omega-3 group was only receiving omega-3s. That is not how it works.  Medical ethics guidelines require that the placebo group receive the standard of care treatment – namely whatever drugs are considered appropriate for that population group.

That means that it has become very difficult to demonstrate that high-risk populations benefit from omega-3 supplementation. Back in the 90s, the standard of care for high risk patients was only one or two drugs. In those days, many studies were reporting beneficial effects of omega-3 supplementation in high risk populations. However, for the past 5-10 years the standard of care for high risk patients is 4-5 medications.

These are medications that reduce cholesterol levels, lower triglyceride levels, lower blood pressure, reduce inflammation, and reduce clotting time. In other words, the drugs mimic all the beneficial effects of omega-3s. (The only difference is that the drugs come with side-effects. The omega-3s don’t.) It is no coincidence that many of the recent studies have come up empty-handed.

The current studies are asking a fundamentally different question. In the 90s, clinical studies asked whether omega-3s reduced heart disease risk in high-risk patients. Today’s clinical studies are asking whether omega-3s provide any additional benefits for patients who are already taking multiple drugs. Personally, I think my readers are more interested in the first question than the second.

Once again, the current meta-analysis is perfectly consistent with this interpretation. The high-risk groups who clearly benefited from omega-3 supplementation were not ones with pre-existing heart disease or who had previously had a heart attack. They were the ones with elevated LDL cholesterol or triglycerides. They were patients who were, either not taking drugs for those risk factors, or patients for whom the drugs were ineffective.

Because subjects in future studies will be taking multiple medications, I predict that even those ongoing studies focusing on high-risk populations will come up empty-handed.

Now you understand why I started this section by saying that I predict many of the ongoing studies will provide incorrect results. I predict that you will see more headlines proclaiming that omega-3s don’t work. However, you won’t be swayed by those headlines because you now know the truth about the flaws in the clinical studies behind the headlines!

What Does This Mean For You?

omega-3 fish oilThe most recent meta-analysis and a careful evaluation of previous studies make two things clear:

  • If you are at high risk of heart disease, omega-3 supplementation is likely to reduce your risk.

We can divide risk factors for heart disease into those we know about, and those we don’t.

  • Risk factors we know about include previously diagnosed heart disease or heart attack, genetic predisposition, age, elevated LDL cholesterol levels, high triglycerides, high blood pressure, inflammation, obesity, metabolic syndrome and diabetes.
  • Unfortunately, there are also risk factors we don’t know about. For too many Americans the first sign of heart disease is sudden death – sometimes just after receiving a clean bill of health from their doctor.
  • If you are not getting enough omega-3s in your diet, omega-3 supplementation is likely to reduce your heart disease risk.

If you are young and healthy, the unfortunate truth is that we may never completely understand the relationship between omega-3 and heart disease. We may not know whether omega-3 supplementation reduces your risk of heart disease. However, I think the overall evidence is strong enough that you should consider adding omega-3s to your diet.

In short, I agree with the authors of the Mayo Clinic Proceedings editorial and the American Heart Association that omega-3-fatty acid intake of at least 1 gram of EPA + DHA per day, either from seafood or supplementation, is a prudent strategy for reducing heart disease risk.

 

The Bottom Line

  • There has been a lot of confusion about the role of omega-3s in reducing heart disease risk.
  • In the 90s, several clinical studies reported that omega-3 supplementation reduced heart disease risk. Most experts, including the American Heart Association, were recommending that most Americans would benefit from adding 500-1,000 mg of omega-3s to their daily diet.
  • In recent years, several clinical studies have reported that omega-3 supplementation has no effect on heart disease risk. [There were some important flaws in those studies, which I discuss in the article above]. Experts started saying that omega-3s were overrated. They were a waste of money.
  • The largest meta-analysis ever undertaken in this area of research has recently reported that omega-3 supplementation decreases risk of heart disease in high-risk population groups. Three subsequent clinical studies have come to essentially the same conclusion.
  • Other studies suggest that omega-3 supplementation is also likely to reduce heart disease risk in individuals with poor omega-3 status, and most Americans have poor omega-3 status.
  • We may never know whether omega-3 supplementation reduces heart disease risk if you are young and healthy. Simply put, not enough young & healthy people develop heart disease within the time-frame of a clinical study for the results to be statistically significant. For this group, the old saying about “An ounce of prevention…” just makes sense.
  • I agree with those experts who recommend at least 1,000 mg/day of omega-3s as a prudent strategy for reducing heart disease risk.
  • There are several major clinical trials in progress studying the efficacy of omega-3s for reducing heart disease risk. Some experts predict that the confusion will be cleared up once they are published. I predict they will only add to the confusion. I predict that many of those studies will show no benefit of omega-3 supplementation, and you will see more headlines proclaiming that omega-3s play no role in heart health. If you have read the article above, you won’t be swayed by those headlines because you will know the truth about the flaws in the studies behind the headlines.

 

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.

Trackback from your site.

Comments (1)

  • Susan Bodlak

    |

    Excellent, clearly reported, and very helpful. Thank you.

    Reply

Leave a comment

Recent Videos From Dr. Steve Chaney

READ THE ARTICLE
READ THE ARTICLE

Latest Article

Can Supplements Help You Live Longer?

Posted June 11, 2019 by Dr. Steve Chaney

Are Supplements The Fountain Of Youth?

Author: Dr. Stephen Chaney

 

It is buyer beware in the supplement industry. I have discussed the dark side of the supplement industry in the first half of my book “Slaying The Supplement Myths.”

I called that section of my book “The Lies of the Charlatans.”  In it, I detailed many of the false claims that some manufacturers make for their supplements. There are claims that their supplements will…

  • Cure what ails you (Just fill in the disease of your choice. Some company will try to tell you they have the cure).
  • Make the pounds melt away.
  • Make you smarter.
  • Make you stronger.
  • Improve your sex life.

Can supplements help you live longer?

The list seems endless…Except for one! I don’t know of any supplement company claiming their supplements make you live longer. Nobody is claiming their supplements are the “Fountain of Youth.”

However, many of you have been asking me about headlines claiming that a recent study showed that supplements don’t extend lives. Could it be that the study generating the recent headlines was designed to disprove a claim nobody was making?

In this issue of “Health Tips From The Professor” I will analyze the study and answer two questions:

  • Is it true?
  • Is it important?

How Was The Study Done?

Every few years the National Center for Health Statistics (a division of the CDC) conducts a massive survey of factors affecting the health of the American population. This survey is called the National Health and Nutrition Examination Survey (NHANES). The NHANES survey includes interviews and examinations of thousands of people across the country.

The interview includes dietary, health-related, demographic, and socioeconomic questions. The examination component includes laboratory tests plus medical, dental, and physiological measurements. The NHANES database is used for many studies such as this one.

The current study (F Chen et al, Annals of Internal Medicine, doi:10.7326/M18-2478, published April 9, 2019) used data from 30,899 US adults aged 20 years or more who participated in 6 cycles of the NHANES survey from 1999 to 2010. The dietary portion of the survey taken by these participants contained questions on the dietary supplements they had used in the 30 days prior to the survey.

The NHANES data were linked to the National Death Index mortality data so that the effect of nutrient intake and supplement use on mortality could be assessed. The median follow-up for the participants in the study was 6.1 years. During that time, 3613 deaths occurred, 945 from heart disease and 805 from cancer.

Of the participants:

  • 71% were white, 11% were non-Hispanic black, and 13% were Hispanic.
  • 9% were female, 49.1% were male.
  • 2 % of the participants reported supplement use in the 30 days preceding the survey.
  • Among the supplement users, the major supplements reported were:
    • Multivitamin/multimineral (74.8%).
    • Vitamin C (40.3%).
    • Calcium (38.6%).
    • Vitamin D (37.6%).
    • Zinc (34.5%).
    • Magnesium (33.3%).

When they compared supplement users with non-supplement users, the supplement users were:

  • More likely to be female and non-Hispanic white.
  • Have higher levels of family education and income.
  • Eat a healthier diet and be more physically active.
  • Less likely to be current smokers, heavy drinkers, or obese.

These are all factors that favor a longer lifespan.  However, the supplement users were also:

  • Older (average age = 50.7 versus 42.8 for non-supplement users).
  • Sicker (They were more likely to have cancer, heart disease, diabetes, high blood pressure, and high cholesterol levels).

These are factors that favor a shorter lifespan.

These are what statisticians refer to as confounding variables. They can influence the results of a study in unexpected ways.

 

Can Supplements Help You Live Longer?

When they looked at the raw data, supplemental use of most-individual nutrients was associated with a lower risk for all-cause death. In simple terms, supplementation appeared to increase lifespan.

However, when the data were statistically adjusted for all of the confounding variables (age, sex, race/ethnicity, education, physical activity, smoking, alcohol intake, diet quality, BMI [a measure of obesity], and diseases the participants had when they entered the study), the effect of supplementation on lifespan became non-significant.

The authors concluded: “Use of dietary supplements was not associated with mortality benefits among a nationally representative sample of U.S adults.”  Those are the headlines you saw from your favorite news source.

What Does This Study Mean For You?

Let’s go back to the two questions I posed about the study at the beginning of this article.

  • Is it true? Can supplements help you live longer?  The study had many weaknesses, which the authors identified in their discussion. Of course, the people writing the headlines never bothered to read the paper, so they were unaware of its weaknesses. Here are some of the major weaknesses reported by the authors:
  • The NHANES questionnaire only asked about supplement use over the preceding 30 days. We have no idea how long the participants had been using those supplements. It could have been years, or it could have been a month. In the words of the authors: “Dietary supplement use was assessed in the previous 30 days, which may not reflect habitual use or capture changes in use [before or] after the baseline assessment.”
  • The supplement users were more likely to have been diagnosed with health conditions such as cancer, heart disease, diabetes, and high blood pressure. It is well documented that diagnosed health conditions motivate some people to initiate supplement use.
  • Finally, there were multiple confounding variables in this study. The conclusion of the study rested on a statistical adjustment of the data to correct for those confounding variables. In the words of the authors: “Residual confounding may still be present.”

That last point reminds me of the famous Mark Twain quote: “There are lies. There are damn lies. And then there are statistics.” Don’t misunderstand me. I am not accusing the study authors of lying. They are some of the top scientists in the field. What Mark Twain and I are saying is that when you rely on statistics, sometimes bad things happen. You can come to erroneous conclusions.

  • Is it important? Even if the conclusion of this study is true, we should ask if it is important. If there had been widespread claims that supplements make you live longer, this would be an important finding. However, nobody I know is making that claim. This study simply reaffirms what most people assumed anyway. There is no fountain of youth.

By the way, the situation is similar for diets. There have been a few claims in the past that healthy diets will help you live longer. However, when those claims have been rigorously evaluated, there is very little effect of diet on lifespan. There have been some studies that have reported a decrease in premature death due to heart disease or cancer. However, death from all causes usually remains unchanged. Once again, the fountain of youth has eluded us.

You may be asking, if supplements don’t increase lifespan, what good are they? The answer is simple. They increase healthspan. Simply put, that means you spend a greater portion of your lifespan in good health.

Of course, now you are probably really confused. You’ve read all those headlines saying that supplements don’t have any effect on your health. The problem is that the studies generating those headlines are flawed. They aren’t asking the right questions. When you look at populations with poor diets, increased needs, genetic predisposition, and/or pre-existing disease, supplementation is often beneficial. I cover this in the second half of my book, “Slaying the Supplement Myths.”  That section is called “The Myths Of The Naysayers.”

 

The Bottom Line

 

A recent study reported that supplements do not reduce mortality. They won’t make you live longer. In this article I provide a detailed analysis of that article. The two important take-aways are:

  • There are several weaknesses in the study. The conclusion may not be accurate.
  • Even if it is accurate, it may not be important. If there had been widespread claims that supplements make you live longer, this would be an important finding. However, nobody I know is making that claim. This study simply reaffirms what most people assumed anyway. There is no fountain of youth. Could it be that the study generating the recent headlines was designed to disprove a claim nobody was making?

The real benefit of supplementation isn’t in increasing your lifespan. It is increasing your healthspan. I cover that in my book, “Slaying The Supplement Myths.”

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.

UA-43257393-1