EPA + DHA Archives - Health Tips From The Professor

Omega-3 Supplements Are Safe

August 27, 2024 by Dr. Steve Chaney

Why Do Clinical Studies Disagree?

Author: Dr. Stephen Chaney

Six weeks ago, the title of my “Health Tips From the Professor” article was, “Are Omega-3 Supplements Safe?” That’s because I was reviewing a study that claimed long-term use of omega-3 supplements increased the risk of atrial fibrillation and stroke. And it had led to headlines like, “Omega-3 Supplements May Increase the Risk of Heart Disease” and “Fish Oil Supplements May Increase The Risk of Stroke and Heart Conditions”.

This week, the title of my article is, “Omega-3 Supplements Are Safe”. I did not choose this title to express my opinion, although I am in general agreement with the statement. I chose that title because the omega-3 pendulum has swung again. The article (M Javaid et al, Journal of The American Heart Association, Volume 13, Number 10: e032390, 2024) I am reviewing today came to the conclusion that omega-3 supplements don’t increase the risk of stroke.

I understand your confusion. You are wondering how scientists can tell you one thing today and the total opposite tomorrow. It is conflicting results like this that cause the public to lose faith in science. And when people lose faith in science they are easily influenced by “snake oil” charlatans on the internet.

So, after I describe this study, I will discuss why scientific studies come up with conflicting results and compare these two studies in detail. That is probably the most important part of this article.

How Was This Study Done?

Scientists from Freeman Hospital and Newcastle University in the UK conducted a meta-analysis combining the data from 120,643 patients enrolled in 11 clinical trials that evaluated the effects of omega-3 supplementation. The inclusion criteria for this meta-analysis were as follows:

The studies were randomized trials that compared omega-3 supplements with placebo or standard treatment. Half the patients received the omega-3 supplement.

The patients were either previously diagnosed with heart disease or were at high risk of developing heart disease.

The studies reported the incidence of bleeding events.

The study asked whether omega-3 supplementation increased the risk of bleeding events (defined as hemorrhagic stroke, intracranial bleeding, or gastrointestinal bleeding) compared to a placebo or standard treatment.

Omega-3 Supplements Are Safe

The results were reassuring for omega-3 supplement users. When compared to a placebo or standard treatment, omega-3 supplements.

Did not increase the risk of overall bleeding events.

Did not increase the risk of hemorrhagic stroke, intracranial bleeding, or gastrointestinal bleeding.

Did not increase the risk of bleeding in patients who were also taking blood thinners (Blood thinners reduce the ability of blood to clot and can lead to bleeding events. This study found that adding omega-3 supplements to these drugs did not increase bleeding risk.

But here is where it gets interesting. One of the 11 studies included in the meta-analysis used a high dose (4 grams/day) of Vascepa, a highly purified ethyl ester of EPA produced by the pharmaceutical company Amarin. When the authors analyzed the data from this study alone, they found that Vascepa:

Increased the relative risk of bleeding by 50% compared to the control group.

- While this sounds scary, the absolute risk of bleeding was only increased by 0.6% compared to the control group.

- I will explain the difference between relative risk and absolute risk below. But for now, you can think of absolute risk as a much more accurate estimate of your actual risk.

The authors of the meta-analysis speculated that the increased bleeding risk associated with the use of Vascepa could be due to the:

High dose of EPA (4 gm/day) or…

Lack of DHA and other naturally occurring omega-3s in the formulation. The authors said:

- The effect of DHA on the endothelial lining is weaker than that of EPA (EPA makes the endothelial lining “less sticky” which reduces its ability to trigger blood clot formation. This is one of the mechanisms by which EPA is thought to decrease blood clot formation.)

- The ability of DHA to inhibit oxidation of Apo-B-containing particles was less sustained than that of EPA (Oxidized Apo-B-containing particles increase the risk of blood clot formation. Inhibition of that oxidation by EPA is another of the mechanisms by which EPA is thought to decrease blood clot formation.)

The authors concluded, “Omega-3 PUFAs [polyunsaturated fatty acids] were not associated with increased bleeding risk. Patients receiving high-dose purified EPA [Vascepa] may incur additional bleeding risk, although its clinical significance is very modest.”

What Is The Difference Between Relative And Absolute Risk?

Relative risk is best defined as the percentage increase or decrease in risk compared to the risk found in a control group. Absolute risk, on the other hand, is the actual increase or decrease in risk in the group receiving the intervention.

Relative risk is an excellent tool for identifying risks. However, it magnifies the extent of the risk, so it can be misleading. For example,

If the absolute risk of some event occurring in the general population was 40%, a 50% increase in relative risk would increase the absolute risk by 20% (40% X 0.5 = 20%) to give a total risk of 60% (40% + 20%). In this case, both the relative and absolute risk are significantly large numbers.

However, if the absolute risk in the general population was 1%, a 50% increase in relative risk would only increase the absolute risk to 1.5%, a 0.5% increase in absolute risk. In this case, the increase in relative risk appears significant, but it is misleading because the absolute increase in risk is a modest 0.5%.

The latter resembles the situation in this study when the authors compared bleeding events in patients receiving Vascepa to those receiving a placebo. The absolute risk of bleeding events in the control group was 1.2%. The risk of bleeding events in the Vascepa group was 1.8%. That is a 50% increase in relative risk but only a 0.6% increase in absolute risk.

Why Do Clinical Studies Disagree?

As I have said many times before, there is no perfect clinical study. Every study has its strengths and its flaws. So, it is perhaps instructive to compare this study and the previous study I reviewed 6 weeks ago. Here are some of the questions I ask when evaluating the strengths and weaknesses of clinical studies.

#1: What kind of study is it?

The previous study was an association study. It can only report on associations. It cannot determine cause and effect. Outcomes like atrial fibrillation and strokes could have been caused by unrelated variables in the population studied.

The current study was a meta-analysis of 11 randomized controlled clinical trials. Because the only difference between the two groups is that one received omega-3 supplements, it can determine cause and effect.

#2: How many people were in the study?

Both studies were very large, so this was not a factor.

#3: How long was the study?

The previous study lasted 12 years. The clinical trials within this meta-analysis lasted one to five years. This is a slight advantage for the previous study because it might be better able to detect risks of chronic use of omega-3 supplements.

#4: How were participants selected?

Participants in the previous study had no previous diagnosis of heart disease while participants in the current study either had a previous diagnosis of heart disease or were at high risk of developing heart disease.

This difference would be relevant if both studies were looking at the benefits of omega-3 supplements. However, the current study was only looking at the side effects of omega-3 supplements, so this is not an important consideration.

#5: How was omega-3 intake monitored?

This was a significant flaw of the previous study. Use of omega-3 supplements was determined by a questionnaire administered when the subjects entered the study. No effort was made to determine whether the amount of omega-3s consumed remained constant during the 12-year study.

The clinical studies within the current meta-analysis were comparing intake of omega-3 supplements to placebo and monitored the use of the omega-3 supplements throughout the study.

#6: What is the dose-response?

This was another serious flaw of the previous study. There was no dose-response data.

The current study provided limited dose-response data. From the data they presented it appeared that the risk of bleeding events was only slightly dose-dependent except for the clinical study with the high dose (4 gm/day) EPA-only Vascepa drug. It was a clear outlier, which is why they analyzed the data from that study independently from the other studies.

#7: What outcomes were measured?

The only common outcome measured in the two studies was hemorrhagic stroke.

The previous study reported that omega-3 supplementation increased the risk of stroke by 5% in the general population. However:

- That result just barely reached statistical significance.

- It was a 5% increase in relative risk. The authors did not report absolute risk.

- It was an association study, so it could not determine cause and effect.

The current study found omega-3 supplementation had no effect on the risk of stroke in a population that either had heart disease or were at high risk of heart disease.

- The exception, of course, was the group taking the high dose Vascepa drug (see below).

#8: Was the risk clinically significant?

As I said above, the previous study only reported relative risk, which can be misleading. However, absolute risk can be calculated from their data. For example,

- The risk of developing atrial fibrillation in the group taking omega-3 supplements was 4.4% (calculated from Table 2 of the manuscript). The authors said that represented a 13% increase in relative risk compared to the group not taking omega-3 supplements. This means the absolute (actual) increase in risk is about 0.6%.

- The risk of stroke in the group taking omega-3 supplements was 1.5% (calculated from Table 2 of the manuscript). The authors said that represented a 5% increase in relative risk compared to the group not taking omega-3 supplements. This means the absolute (actual) increase in risk is about 0.08%.

In the current study the increased risk of stroke in the group taking the high-dose (4 gm/day) EPA-only Vascepa drug was 50% for relative risk, but only 0.6% for absolute risk.

- The authors of the current study argued that, based on absolute risk, the risk of stroke for people taking Vascepa was “clinically insignificant”. I would argue the same is true for the results reported in the previous study and the headlines they generated.

#9: Who sponsored the study?

The previous study was supported by the Bill and Melinda Gates Foundation, an organization that has no obvious interest in the outcome of the study.

The current study is sponsored by Amarin, the pharmaceutical company that manufactures and markets Vascepa.

- However, to their credit, the authors made no effort to hide the negative data about Vascepa.

- - In fact, they highlighted the negative data, noted that the increased bleeding risk with Vascepa was different from the omega-3 supplements studied, and offered possible explanations for why a high potency, EPA-only supplement might increase the risk of bleeding more than a lower potency omega-3 supplement containing both EPA and DHA.

- They did, however, choose to emphasize the 0.6% absolute increase in bleeding risk rather than the 50% relative increase in bleeding risk. However, as I noted above absolute risk is a more accurate way to report risk, especially when the risk in the control group is only 1.2%.

Perspective On This Comparison:

You may be tempted to conclude that the previous study was garbage. Before you do, let me provide some perspective.

The data for that study came from the UK Biobank, which is a long-term collection of data by the British government from over 500,000 residents in the United Kingdom. The data are made available to any researcher who wants to study links between genetic and environmental exposure to the development of disease. However, the data were not collected with any particular study in mind.

This is why omega-3 intake was only determined at the beginning of the study and there was no dose-response information included. The experimental design would have been different if the study were specifically designed to measure the influence of omega-3 supplementation on health outcomes. However, because of cost, the sample size would have been much smaller, which would have made it difficult to show any statistically significant results.

Relative risk rather than absolute risk is almost universally used to describe the results of clinical studies because it is a larger number and draws more attention. However, as I described above, relative risk can be misleading. In my opinion, both relative and absolute risk should be listed in every publication.

What Does This Study Mean For You?

Scientists know that every study has their flaws, so we don’t base our recommendations on one or two studies. Instead, we look at the totality of data before making recommendations. When looking at the totality of data two things stand out.

The bleeding risk with Vascepa is not unique. There are some studies suggesting that high dose (3-4 gm/day) omega-3 supplements containing both EPA and DHA may increase bleeding risk, although probably not to the same extent as Vascepa.

An optimal Omega-3 Index of 8% is associated with a decreased risk of heart disease and does not appear to increase the risk of atrial fibrillation or bleeding events such as hemorrhagic stroke. And for most people, an 8% Omega-3 Index can be achieved with only 1-2 gm/day of omega-3s.

So, my recommendations are the same as they were 6 weeks ago.

Be aware that high-dose (3-4 gm/day) of omega-3 supplements may cause an increased risk of atrial fibrillation and stroke, but the risk is extremely small.

Omega-3 supplementation in the 1-2 gm/day range appears to be both safe and effective.

I recommend getting your Omega-3 Index determined, and if it is low, increasing your omega-3 intake to get it into the 8% range.

The Bottom Line

A recent meta-analysis concluded that omega-3 supplementation does not increase the risk of bleeding events, including hemorrhagic stroke, intracranial bleeding, and gastrointestinal bleeding.

The exception was the high-dose (4 gm/day), EPA-only drug Vascepa, which increases bleeding risk from 1.2% to 1.8%, a 0.6% increase in absolute risk.

This study contradicts a previous study I shared with you only six weeks ago, so I made a detailed comparison of the strengths and weaknesses of each study.

For more details on these studies and what they mean for you, 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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My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

My answer is, “Yes, as long as you share only the article without any additions or alterations. In particular, you should avoid adding any mention of your company or your company’s products. If you were to do that, you could be making what the FTC and FDA consider a “misleading health claim” that could result in legal action against you and the company you represent.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

_______________________________________________________________________

About The Author

Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”.

Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry text books for medical students.

Since retiring from the University of North Carolina, he has been writing a weekly health blog called “Health Tips From the Professor”. He has also written two best-selling books, “Slaying the Food Myths” and “Slaying the Supplement Myths”. And most recently he has created an online lifestyle change course, “Create Your Personal Health Zone”. For more information visit https://chaneyhealth.com.

For the past 45 years Dr. Chaney and his wife Suzanne have been helping people improve their health holistically through a combination of good diet, exercise, weight control and appropriate supplementation.

Do Omega-3s Reduce Osteoarthritis Pain?

April 16, 2024 by Dr. Steve Chaney

How Do Rheumatoid And Osteoarthritis Differ?

Author: Dr. Stephen Chaney

This week I am concluding my series on recent omega-3 advances by reviewing a meta-analysis that asks whether omega-3s are beneficial for people with osteoarthritis.

This is an important question because osteoarthritis affects around 32.5 million adults in the United States, and that number is increasing each year as our population ages. Osteoarthritis causes pain and disabilities that can significantly affect quality of life.

And the costs are high. Health care costs due to osteoporosis are around $140 billion/year. And when you include lost workdays, the annual cost is around $468 billion.

There are several medications for reducing symptoms of osteoarthritis. But they each have side effects and some patients cannot tolerate them. Joint replacement surgery is the final resort. But the recovery period is long, and the surgery isn’t always effective. For both reasons many patients with osteoarthritis are looking for natural solutions.

Most of the research on omega-3s and arthritis has been done with patients who have rheumatoid arthritis. Omega-3 supplements have been shown to reduce the pain, swelling of the joints, and inflammation associated with rheumatoid arthritis for many people with the disease.

Based on several dose-response studies, the NIH says the optimal dose is around 2.7 gm/day of EPA + DHA but cautions not to go above 3 gm/day without your doctor’s OK.

The evidence is less clear for omega-3s and osteoarthritis. Some studies suggest that EPA + DHA reduce the pain and inflammation associated with osteoarthritis. But other studies have come up empty. There is no consensus as to whether omega-3s are beneficial for people with osteoarthritis.

When there is disagreement between individual studies, a meta-analysis of the studies is often helpful. By pooling the data from multiple studies, a meta-analysis can smooth out some of the differences between the studies and accumulate enough data points to discover effects that would not have been statistically significant with the smaller data sets from individual studies.

With that in mind, the authors of this manuscript (W Den et al, Journal of Orthopaedic Surgery and Research, 18: 381, 3023) performed a meta-analysis on the data obtained from 9 double-blind, placebo-controlled studies looking at the effect of omega-3s versus a placebo on both pain and joint mobility in osteoarthritis patients.

How Do Rheumatoid And Osteoarthritis Differ?

While the causes of rheumatoid arthritis and osteoarthritis are very different, there are some underlying similarities between the two diseases that suggest both might benefit from omega-3 supplementation.

Rheumatoid Arthritis: Rheumatoid arthritis is thought to be an autoimmune disease, which means that our immune system attacks our cells rather than foreign invaders. It results in chronic inflammation that attacks our joints and can affect other tissues in our body.

It initially affects the lining of our joints which can result in painful, swollen joints. As the disease progresses it can also lead to bone erosion and joint deformity.

Osteoarthritis:Osteoarthritis is generally thought of as a “wear and tear” disease. It is associated with sports injuries and accidents. It is also associated with stress to particular joints due to repeated motions associated with either sports or a job. Obesity also increases wear and tear of the joints because it increases the load on the joints.

The wear and tear causes the cartilage that cushions the junction between bones to deteriorate. Eventually, the cartilage deteriorates to the extent that bone is grinding against bone, which can lead to bone loss and deformities.

Eventually, this results in an inflammation of the joint lining which causes pain and accelerates bone loss. It also causes deterioration of the connective tissue which holds bones together and connects them to muscle.

What Do These Diseases Have In Common? Inflammation is the common factor associated with both rheumatoid and osteoarthritis, and many studies suggest that omega-3s reduce inflammation. In the simplistic description of the two diseases I shared above, it sounds like inflammation occurs much earlier in the disease process for rheumatoid arthritis than for osteoarthritis. This might suggest that omega-3s could be more effective at reducing the symptoms and progression of rheumatoid arthritis than of osteoarthritis.

However, we know that the risk of developing osteoarthritis is increased by chronic inflammation caused by obesity, diseases like diabetes, and/or an inflammatory diet.

How Was This Study Done?

This study was a meta-analysis of 9 double-blind, placebo-controlled clinical studies looking at the effect of omega-3 fatty acids on the pain and loss of joint mobility associated with osteoarthritis. These studies were performed in countries from around the world and included a total of 2,070 participants.

The criteria for inclusion in the meta-analysis were:

1) The articles were written in English.

2) The studies had to be double-blind, placebo-controlled studies (The gold standard for clinical studies).

3) Patients with osteoarthritis were randomly assigned to an intervention group receiving omega-3 supplementation or a placebo group receiving olive oil or another plant oil.

4) The studies measured efficacy and safety outcomes including joint pain (efficacy), joint mobility (efficacy), and treatment-related adverse events (safety).

5) Patients in both the omega-3 and placebo groups were using medications to reduce osteoarthritis symptoms when they were enrolled in the study and were advised to continue with their prescribed medicines for the duration of the study.

The characteristics of the clinical studies included in this meta-analysis were:

Sample size (47-1221), Average = 230.

Mean age (55.9-68), Average = 63.

% men (13.8-45.1%), Average = 31%.

Omega-3 (EPA + DHA) dose (350 mg/day – 2,400 mg/day), Average = 1,085 mg/day.

Do Omega-3s Reduce Osteoarthritis Pain?

When the data from all 9 studies were combined in a single meta-analysis, omega-3 (EPA + DHA) supplementation:

Reduced joint pain by 29% compared to the placebo.

Increased joint mobility by 21% compared to the placebo.

Was not associated with any adverse effects.

The authors concluded, “The results of the meta-analysis indicate that supplementation with omega-3 fatty acids is effective to relieve pain and improve joint function in patients with osteoarthritis, without increasing the risk of treatment-related adverse events. These findings support the use on omega-3 fatty acid supplementation as an alternative treatment for osteoarthritis.”

What Are The Strengths and Limitations Of This Study?

Strengths:

All the studies included in this meta-analysis were randomized, double-blind, placebo-controlled studies (the gold standard for clinical trials).

All the individual studies that qualified for this meta-analysis found that omega-3 supplementation reduced joint pain and improved joint mobility. This improves confidence that the conclusions of the meta-analysis are correct. The meta-analysis simply improved the statistical significance of this conclusion by combining the data from the individual studies.

Limitations:

The biggest limitation was that the individual studies included in this meta-analysis were not performed under the guidelines of the “Fatty Acids and Outcomes Research Consortium” that I discussed in last week’s issue of “Health Tips From the Professor”.

- The “Fatty Acids and Outcomes Research Consortium” guidelines harmonize the designs of individual studies, which strengthens the meta-analysis.

- - In contrast, the design of the individual studies within this meta-analysis was very different, which prevented the meta-analysis from being able to determine the optimal dose of omega-3 supplements and the minimum time required for omega-3 supplementation to significantly reduce the symptoms of osteoarthritis.

- The “Fatty Acids and Outcomes Research Consortium” guidelines would have also required these studies to measure tissue levels of omega-3s (something called Omega-3 Index) at the beginning and end of each study. This was not done in any of these studies.

- - This is important because if a patient’s tissue levels of omega-3s at the beginning of the study were already in the optimal range, you would expect little additional benefit from supplementation for that patient.

All the individual studies were very small. This limits the ability of these studies to provide definitive conclusions. Unfortunately, this is probably unavoidable.

- Double blind, placebo-controlled clinical studies are expensive. Only major pharmaceutical companies have the multi-million-dollar budgets required to conduct large double blind, placebo-controlled clinical studies that would provide more definitive evidence that omega-3 supplementation reduces the symptoms of osteoarthritis – and the follow-up studies that would determine the optimal dose of omega-3 supplements and the minimum time required to show an effect of omega-3 supplementation.

The patients in these studies were already taking medications to reduce their osteoarthritis symptoms prior to entering the study and were instructed to continue taking those medications during the study. This means that the studies were not asking whether omega-3s alone were effective at reducing osteoarthritis symptoms. They were asking whether omega-3 supplementation provided any additional benefits for people who were already taking medications to reduce symptoms.

- Unfortunately, this is also probably unavoidable. Current guidelines consider it unethical to withhold the medical “standard of care” from any patient in a clinical trial.

What Does This Study Mean For You?

This study, while not definitive, strengthens the evidence that omega-3 supplements containing EPA + DHA may reduce joint pain and improve joint mobility for people with osteoarthritis. It also shows that the doses required to achieve these benefits are not associated with any significant side effects.

While large scale double blind, placebo-controlled clinical studies to confirm these conclusions would be nice, they are unlikely to occur for the reasons discussed above.

The investigators said, “[This study shows that] supplementation of omega-3 fatty acids is effective to relieve pain and improve joint function in patients with osteoarthritis…These findings support the use of omega-3 fatty acid supplementation as an alternative treatment for osteoarthritis.”

This might lead you to believe that omega-3 fatty acids can potentially replace medications for reducing osteoarthritis pain and loss of joint mobility. That may be true, but that is not what the study showed.

Patients in both the omega-3 and placebo group continued their prescribed medicines for osteoarthritis. In reality, the study only shows that omega-3s provide additional benefit for people already taking osteoarthritis medications. The effect of omega-3 supplements by themselves has not been tested and, as I discussed above, is not likely to be tested in the foreseeable future.

However, the use of omega-3 supplements may allow you to reduce or eliminate the medications you are on for osteoarthritis and may delay the need for joint replacement surgery. Of course, if you wish to reduce/eliminate your medications and/or delay joint replacement surgery, I recommend consulting with your doctor first.

Finally, this study provides no information on the optimal dose of omega-3s. Some studies suggest the dose of omega-3s needed to reduce osteoarthritis symptoms may be less than that required to reduce rheumatoid arthritis symptoms, but that evidence is weak.

In the absence of good dose response data, I recommend you aim for an omega-3 index of 8%. You will find a more detailed discussion of the Omega-3 Index and how to use it in last week’s “Health Tips From the Professor” article .

The Bottom Line

A recent meta-analysis looked at the effect of omega-3 supplementation on the pain and lack of joint mobility associated with osteoarthritis.

The study showed that omega-3 (EPA + DHA) supplementation:

Reduced joint pain by 29% compared to the placebo.

Increased joint mobility by 21% compared to the placebo.

Was not associated with any adverse effects.

For more details about the study and what it means for you, 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.

_____________________________________________________________________________

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

_______________________________________________________________________

About The Author

Dr. Chaney has a BS in Chemistry from Duke University and a PhD in Biochemistry from UCLA. He is Professor Emeritus from the University of North Carolina where he taught biochemistry and nutrition to medical and dental students for 40 years. Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”. Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry text books for medical students.

The Good News About Omega-3s And Stroke

April 9, 2024 by Dr. Steve Chaney

How Do Omega-3s Affect The Two Types Of Stroke?

Author: Dr. Stephen Chaney

I am continuing my series on recent omega-3 breakthroughs. Last week I reviewed a study showing that the omega-3s EPA and DHA lowered blood pressure. Since high blood pressure is a major contributing factor to stroke risk, it only makes sense that EPA and DHA would also decrease the risk of strokes.

In last week’s article I mentioned that high blood pressure is called a silent killer. That is because the symptoms of high blood pressure are easy to ignore and often confused with other illnesses.

For many people the first indication they have a problem is when they have a stroke, which either kills them or forever impacts their quality of life. Let me share some statistics with you.

Every 40 seconds someone in the United States has a stroke. One in four adults over the age of 25 will have a stroke in their lifetime.
Every 4 minutes someone in the United States dies from a stroke. For many of them sudden death is the first indication they had a health problem.
The overall incidence of strokes has increased 60% in the last 20 years with most of that increase (65%) coming from younger adults (ages 20 to 45)
The cost of treatment, rehabilitation, and lost wages from stroke was $891 billion in 2020 and is projected to increase to $2.3 trillion in 2050.

Any way you look at it, the personal and financial costs of strokes are immense.

How Do Omega-3s Affect The Two Types Of Stroke?

There are two major kinds of stroke – ischemic stroke, which is caused by a thrombus (blood clot) in the carotid arteries leading to the brain, and hemorrhagic stroke, which is caused by bleeding from small blood vessels in the brain. Ischemic stroke accounts for around 85% of all strokes.

Ischemic strokes are caused by atherosclerosis, the buildup of fatty plaques in the walls of the carotid arteries, followed by the formation of a blood clot which lodges in the narrowed arteries. As you might expect, the prevention and treatment of ischemic strokes are similar to the prevention and treatment of heart attacks.

EPA and DHA have been shown to:

Reduce inflammation, which is associated with increased risk of heart disease and stroke.

Reduce blood pressure. High blood pressure damages the endothelial lining of blood vessels, which can lead to either build up of atherosclerotic plaque or rupturing of the blood vessels.

Reduce platelet aggregation and blood viscosity, which reduces the potential for inappropriate blood clots forming in the carotid arteries.

[When you cut yourself, you want a blood clot to form to stop the bleeding. That is an example of appropriate blood clot formation. However, when a blood clot forms within your arteries, it can prevent blood from reaching surrounding tissues. This is an example of inappropriate blood clot formation.]

Reduce the risk of atherosclerotic plaques rupturing. Rupturing of atherosclerotic plaques triggers blood clot formation, so this also decreases the risk of inappropriate blood clots forming in the carotid arteries.

Based on the known effects of EPA and DHA, it is not surprising that they would decrease the risk of ischemic strokes. But what about hemorrhagic strokes? Here the answer is not as clear cut.

In a previous clinical study 4 gm/day of purified EPA without DHA was associated with a slightly increased risk of bleeding events but did not increase the risk of hemorrhagic stroke.

High doses of pharmaceutical grade EPA have also been associated with a slightly increased risk of atrial fibrillation (Afib). In contrast, previous studies have shown that higher dietary intake of EPA + DHA are associated with a lower risk of Afib.

At present, we don’t know whether the increased risk of bleeding events and Afib are only seen at very high doses of omega-3s or are due to the use of pharmaceutical grade EPA without DHA and any of the other naturally occurring omega-3s.

However, this uncertainty has led some experts to warn that omega-3s may be a two-edge sword. They might increase the risk of hemorrhagic stroke while decreasing the risk of ischemic stroke. This uncertainty was part of the rationale for the study (JH O’Keefe et al, Stroke, 55: 50-58, 2024) I am describing today.

How Was This Study Done?

This study was a meta-analysis of 29 clinical studies looking at the effect of omega-3 fatty acids on the risk of both ischemic and hemorrhagic stroke. These studies were performed in 15 countries from around the world and included a total of 183,291 participants.

One major drawback of many meta-analyses is that each study in the meta-analysis is independently designed. Sometimes the studies are so different that it is difficult to fit them together in a coherent pattern.

A major strength of this meta-analysis is that all the studies were conducted within the “Fatty Acid and Outcome Research Consortium” which specifies a general protocol for the design of each study within that consortium.

For example, estimates of dietary omega-3 intake can be inaccurate and the uptake and utilization of both dietary and supplemental omega-3s vary from person to person. Because of that the Fatty Acid and Outcomes Research Consortium guideline specifies that studies rely on biomarkers of omega-3 levels in the body rather than the amount of omega-3s consumed.

The most frequently used biomarker was the percentage of omega-3s incorporated into the fatty portion of red blood cell membranes. Some studies used other biomarkers, such as the percentage of omega-3s incorporated into the fatty portion of plasma phospholipids or cholesterol-containing phospholipid particles (LDL and HDL for example).

In each case, the percentage of omega-3s is used to calculate something called an “Omega-3 Index”. Previous studies have shown that an Omega-3 Index of 4% or less correlates with a high risk of heart disease, and an Omega-3 Index of 8% or more correlates with a low risk of heart disease. In essence, this study correlated Omega-3 Index with the risk of stroke.

The Fatty Acids and Outcomes Research Consortium harmonized the studies included in this meta-analysis in several other ways, but the use of Omega-3 Index rather than omega-3 consumption was the most important.

Other key characteristics of the studies included in this meta-anaysis were:

The average age of participants was 65 years.
82% of the participants were white and 53% were women.
The average length of follow-up was 14 years (range = 5-30 years).
10,561 participants (5.8%) suffered a stroke during follow-up (78% ischemic, 11% hemorrhagic, and 11% unspecified).

The Good News About Omega-3s and Stroke

The participants in these studies were divided into quintiles based on their Omega-3 Index. When those in the highest quintile (≥ 8%) were compared with those in the lowest quintile (≤ 4%):

Risk was reduced by 17% for total stroke and 18% for ischemic stroke. There was no effect on hemorrhagic stroke.

When the effect of individual components of the Omega-3 Index were analyzed:

For EPA + DHA risk was reduced by 17% for total stroke and 18% for ischemic stroke. There was no effect on hemorrhagic stroke.

For EPA risk was reduced by 17% for total stroke and 18% for ischemic stroke. There was no effect on hemorrhagic stroke. (You are probably starting to detect a pattern).

For DHA the results were only slightly different. Risk reduction was 12% for total stroke and 16% for ischemic stroke. There was no effect on hemorrhagic stroke.

For DPA, a minor component of the Omega-3 Index, there was no significant effect on total, ischemic, or hemorrhagic stroke.

There was a linear dose-response for the effect of EPA, DHA, and the two combined on the reduction in risk for both total and ischemic stroke.

When they looked at subgroups within the analysis, the results were the same for:

Age (<65 compared to >65).
Gender.
Studies that lasted less than 10 years and studies that lasted more than 10 years.
The presence of preexisting Afib.
The presence of preexisting cardiovascular disease.

The authors concluded, “In summary, this harmonized and pooled analysis of prospective studies showed that long-chain omega-3 levels were inversely associated with risk of total and ischemic stroke but were unrelated to risk of hemorrhagic stroke. Thus, higher dietary intake of DHA and EPA would be expected to lower risk of stroke.”

What Does This Study Mean For You?

Key Takeaways From This Study: The most important takeaway from this study is that reasonable amounts of EPA and DHA from either diet or supplementation are unlikely to increase your risk of hemorrhagic stroke (I will define reasonable below).

That is important to know because this and several other studies show that EPA and DHA decrease the risk of ischemic stroke, which accounts for around 85% of total strokes. This study shows you can reduce your risk of ischemic stroke without fearing that you will increase your risk of hemorrhagic stroke.

This study also reaffirms the importance of relying on Omega-3 Index rather than the dosage of omega-3s in a supplementation. Previous studies have shown there is significant individual variability in the uptake and utilization of dietary omega-3s.

Finally, this study shows you don’t need huge amounts of EPA and DHA to significantly decrease your risk of stroke and cardiovascular disease in general. An Omega-3 Index of ≥ 8% is sufficient to accomplish both.

How Much Omega-3s Do You Need? The authors of this manuscript are experts on the Omega-3 Index, and they estimated that:

To raise your Omega-3 Index from 5.4% (the median Omega-3 Index in these studies) to 8% would require about 1,000 mg/d of EPA + DHA.

To raise your Omega-3 Index from 3.5% (the lowest Omega-3 Index quintile in these studies) to 8% would require about 1,600 mg/d of EPA + DHA.

These intakes are well within the American Heart Association recommendations for reducing the risk of stroke and cardiovascular disease and are easily achievable from diet and supplementation.

But these estimates are based on averages, and, as I noted above, none of us are average. We differ in our ability to absorb and utilize omega-3s. So, I recommend relying on your Omega-3 Index rather than a dose of omega-3s that’s right for the average person but may not be right for you.

My recommendation would be to start with an Omega-3 test. If you are below 8%, start with the dosage of EPA + DHA the authors of today’s study recommended. Then retest in 6 months and adjust your dose based on the results of that test.

How Much Is Too Much? As I mentioned above, the dose response was linear for Omega-3 Index versus reduction in risk of total and ischemic strokes. So, the question becomes whether you might wish to increase your Omega-3 Index above 8% to achieve an even better reduction in stroke risk.

That is a very personal decision that only you can make but let me share some facts to help you make that decision.

As I mentioned above, a previous clinical trial showed an increased risk of bleeding events and Afib at a dosage of 4 gm/day of pure EPA. We don’t know whether that was because of the dose or the use of a formulation that contained only EPA without DHA and other naturally occurring long-chain omega-3s.

In that study the increase in bleeding events and Afib was observed in <5% of participants, which suggests that those side effects may be limited to certain high-risk individuals.

- In this context, high risk might include individuals with preexisting Afib, individuals with a tendency towards excess bleeding, and patients on blood thinning medications.

- However, only your physician knows all your risk factors. If you have health issues or are on medications, it is always a good idea to check with your physician before changing your omega-3 intake. And if you are considering high-dose omega-3 supplementation or exceeding an 8% Omega-3 Index, I strongly recommend that you consult with your physician first.

The Bottom Line

A recent study looked at the effect of omega-3 levels in red blood cells and other tissues (something called Omega-3 Index) on the risk of various types of stroke.

When individuals with an Omega-3 Index ≥ 8% were compared with those with an Omega-3 Index of ≤ 4%:

Risk was reduced by 17% for total stroke and 18% for ischemic stroke (stroke caused by blood clots in the carotid arteries). There was no effect on hemorrhagic stroke (stroke caused by bleeding from small blood vessels in the brain).

This study represents an important breakthrough. There is good evidence that increased EPA + DHA from food and/or supplements reduces the risk of ischemic stroke. But some experts have cautioned it might also increase the risk of hemorrhagic stroke. This study puts that fear to rest.

For more details about the study and what it means for you, 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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