Can Omega-3 Supplements Resolve or Exacerbate Conflict in Studies?

Fish oil studies reveal a rift in the science around the pros and cons of omega-3 fatty acids, raising questions about how much a person should take—if any at all.

A Case Study

Fish oil, a rich source of omega-3 fatty acids, is commonly recommended as a dietary intervention to prevent cardiovascular disease. The American Heart Association recommends 0.5 to 1.8 grams per day of combined EPA and DHA, two forms of omega-3s, as either fatty fish or supplements.

The latest fish oil findings published in BMJ Medicine are just another chapter in the ongoing saga of scientific disputes over the health impacts of various foods and supplements, including red meat, saturated fat, and eggs.

To understand this premise, we need to dig into how science works and take a larger look at the research done to date.

Related Stories

This article serves as a case study of how the media often reports sanitized sound bites and governing agencies decree sweeping recommendations and health policies based on an oversimplification of complex health issues.

Background

In the United States, a person dies from cardiovascular disease (CVD) every 33 seconds, according to the Centers for Disease Control and Prevention.

The study noted that previous clinical studies, as well as those analyzing population-wide patterns, have found people were less likely to suffer from a stroke if they supplemented with omega-3 fatty acids. Other studies found that people didn’t benefit at all.

Study Objectives: Clarifying the Effects of Fish Oil

The BMJ Medicine study examined the effects of fish oil supplements on different stages of cardiovascular health, including atrial fibrillation (abnormal heart rhythm), major adverse cardiovascular events, and death. Major adverse cardiovascular events were defined as stroke, myocardial infarction, and/or heart failure.

415,737 people, aged 40-69, participated in the study.

The researchers asked two primary questions:

1. Primary Prevention: How does fish oil affect the development of atrial fibrillation, major adverse cardiovascular events, and death in individuals with no known CVD?

Study Design

Participants were categorized as regular users or non-users of fish oil supplements based on self-reported data collected during baseline surveys. The study followed the participants for a median of 11.9 years, tracking incidences of atrial fibrillation, heart failure, stroke, myocardial infarction, and death through various health records. The study adjusted for numerous covariates, including age, gender, lifestyle factors, and pre-existing health conditions.

Key Findings

The results from the study were divided into two distinct categories—primary prevention and secondary prevention.

Primary Prevention in Healthy People

For people with no known CVD at baseline, regular use of fish oil supplements was associated with a significant increased risk of developing atrial fibrillation. No significant effect was found on the transition from a healthy state to major adverse cardiovascular events or death. However, detailed analysis revealed a clearer picture:

• Atrial Fibrillation: 13 percent increased risk
• Stroke: 5 percent increased risk
• Heart Failure: 8 percent reduced risk
• Myocardial Infarction: No significant effect

The increased risk of first-time heart disease and stroke among healthy people led the researchers to caution against the use of fish oil without clear evidence of its benefits.

Secondary Prevention in People With Known Cardiovascular Disease

For participants who already had a diagnosis of atrial fibrillation at baseline, fish oil supplementation showed protective effects, reducing the risk of transitioning to major adverse cardiovascular events and death. Specific benefits were noted as follows:

• Myocardial Infarction: 15 percent risk reduction
• Heart Failure: 5 percent risk reduction
• Stroke: No effect

Fish oil supplements might help manage CVD in people with atrial fibrillation, according to the results. It reduced risks of heart failure, myocardial infarction, and death, although it did not affect the risk of stroke.

Major Cardiovascular Events

For people who experienced major adverse cardiovascular events during the study, fish oil supplementation had no significant effect on overall mortality. However, the effect on specific outcomes was conflicting:

• Heart Failure: 9 percent reduced risk of death
• Myocardial Infarction: 3 percent increased risk of death
• Stroke: 4 percent increased risk of death

Fish oil may have been beneficial for people who had heart failure but could pose risks for others, particularly those who had a stroke or heart attack, according to the study.

Why fish oil affects different stages of health differently was unclear.

Study Strengths and Limitations

The BMJ Medicine study included a large sample size, extended time frame, and analyzed multiple states of CVD whereas most studies “tended to assess the role of fish oil at a certain stage of cardiovascular disease,” according to the study.

However, because the study simply observed associations in a large population, it could not specifically say what caused those associations.

The researchers stated that genetics, age, sex, smoking status, and the use of statins and antidiabetic medications might influence the effects that supplementing with fish oil has on cardiovascular events.

Additionally, participants self-reported their fish oil consumption without guidance on dosage or quality, leading to a wide range of usage patterns.

Dr. Peter Osborne, a diplomat with the American Clinical Board of Nutrition and founder of Origins Healthcare, took issue with the study’s approach.

“To do a retrospective trial where they are just saying these people have claimed to use omega-3 and then trying to associate that with an increased risk of poor outcomes is ridiculous,” he told The Epoch Times in an interview.

Additionally, most of the study’s participants were from the white ethnic group, which may limit the application of the findings to a broader global population.

Comparison With Previous Studies

The results of the BMJ Medicine study were generally in line with several previous randomized controlled trials and meta-analyses.

Previous Findings of Increased Risk of Atrial Fibrillation With Omega-3 Supplement

1. Meta-Analysis: 25 percent increased risk of atrial fibrillation was reported in Circulation in 2021 based on an analysis of seven randomized controlled trials.
2. REDUCE-IT Trial: 48 percent increased risk of atrial fibrillation was reported in the New England Journal of Medicine in 2018 based on a placebo-controlled trial involving 8,179 patients.
3. Meta-Analysis: 26 percent increased risk of atrial fibrillation was reported in The Lancet in 2021 based on an analysis of 38 randomized controlled trials.
4. STRENGTH Trial: 69 percent increased risk of atrial fibrillation was reported in the Journal of the American Medical Association in 2020 based on a randomized clinical trial including 13,078 patients.

The researchers of the STRENGTH trial concluded: