Michael Hunter, MD on Medika Life

Fish Oil Reversal: New Study Says Supplements Might Not Be What You Think for Heart Health

I PREVIOUSLY HAD SLIGHTLY HIGH CHOLESTEROL LEVELS. I added fish oil to diet improvements and regular exercise in this context. However, a new study suggests that the fish oil supplements might not do what I thought.

Here’s the context of why I incorporated the supplements into my routine.

Fish oil supplements have been hailed as a wonder weapon for heart health for decades.

Doctors routinely recommended them, and health-conscious individuals faithfully popped their daily dose.

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My Goals

In this article, we will delve into the recent study published in BMJ Medicine that challenges the long-held belief about the benefits of fish oil supplements for heart health.

We will explore the potential impact of this new research and its implications for individuals who have incorporated fish oil capsules into their daily routines.

Additionally, we will discuss the traditional benefits associated with fish oil supplements and examine the study’s surprising findings, offering a comprehensive analysis of the implications for heart health.

First, a look at the potential benefits of fish oil supplements.

Fish Oil: Supporting Heart Health

Fish oil supplements, which boast high omega-3 fatty acids, EPA, and DHA, have been a mainstay in heart-healthy routines for years.

Traditionally, many viewed fish oil supplements as beneficial for heart health due to their high content of omega-3 fatty acids, particularly EPA eicosapentaenoic acid) and DHA (docosahexaenoic acid).

Here’s a breakdown of some potential benefits:

  • Reduced triglyceride levels: There’s growing evidence that omega-3 fatty acids can significantly reduce blood triglyceride levels, a type of fat associated with an increased risk of heart disease.
  • Lower cholesterol levels. The effect on cholesterol is more nuanced. While there may be a slight increase in “good” HDL cholesterol, some studies suggest a possible increase in “bad” LDL cholesterol.
  • Better mental health. Omega-3 fatty acids might help prevent the onset or improve the symptoms of some mental health conditions like depression.
  • Potential anti-inflammatory effects: Omega-3s possess some anti-inflammatory properties, which may be helpful in conditions like rheumatoid arthritis.
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  • Improve brain function: Some studies suggest omega-3s play a role in cognitive function and benefit brain health as we age.
  • Pregnancy support. While some research suggests fish oil supplements during pregnancy and breastfeeding might benefit a child’s cognitive development, vision, and allergy risk, more studies are needed to confirm these effects definitively. It’s important to discuss any supplement use with your doctor before starting them, especially during pregnancy or breastfeeding.

Fish Oil, Heart Disease, and Stroke Risk

Given my current use of fish oil supplements, a recent British Medical Journal Medicine study on its pros and cons caught my eye.

Here are the research objectives:

  • Participants: Over 415,000 individuals from the UK Biobank study, aged 40–69, were included.
  • Objective: To assess the link between fish oil supplements and the risk of major cardiovascular events, including atrial fibrillation (irregular heartbeat), heart attack, stroke, and heart failure. Researchers also tracked deaths from any cause.

Study Follow-up

Researchers surveyed participants between 2006 and 2010 to gather baseline information on their health habits, including fish oil supplement use, dietary fish intake, and other lifestyle factors.

They then used medical records to track participants’ health outcomes until March 2021 or their death.

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About one-third (31.5 percent) of the participants reported taking fish oil supplements regularly. This group tended to be:

  • Older
  • White
  • More likely to be female
  • Have higher alcohol consumption and oily fish intake
  • Less likely to be current smokers or live in deprived areas

Key Findings

The study revealed a surprising association between fish oil supplements and heart health in individuals with no prior cardiovascular issues.

The findings indicated that using fish oil supplements had different roles in cardiovascular health, disease progression, and death.

Fish oil hurts those with no known cardiovascular disease

For those with no known cardiovascular disease at the start of the monitoring period, regular use of fish oil supplements was associated with:

  • A slightly (1.13 times) heightened risk of developing atrial fibrillation
  • A 1.05-fold rise in stroke risk.

Fish oil helps those with known cardiovascular disease.

Among those who had cardiovascular disease at the start of the monitoring period, regular use of fish oil supplements was associated with:

  • A one-seventh (15 percent) lower risk of progressing from atrial fibrillation to a heart attack
  • A one-tenth (9 percent) lower risk of progressing from heart failure to death.

In-depth Analysis

Further in-depth analysis revealed that age, sex, smoking, consumption of non-oily fish, high blood pressure, and use of statins and blood pressure-lowering drugs changed the associations observed.

Regular use of fish oil supplements and the risk of transitioning from good health to heart attack, stroke, or heart failure was 6% higher in women and 6% higher in non-smokers.

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The protective effect of these supplements on the transition from good health to death was greater in men (7% lower risk) and older participants (11% lower risk).

Study Problems

The researchers acknowledge this is an observational study, meaning it can’t prove cause and effect.

For example, people who take fish oil supplements might also have other lifestyle habits that influence their heart health. Observational studies are a lower-quality type of research.

Additionally, the study needed more information on the dosage or specific formulations of the fish oil supplements used by participants.

This omission makes it difficult to draw precise conclusions about the impact of different fish oil types or amounts.

Finally, the study population was predominantly white.

The findings may not be generalizable to people of other ethnicities.

We require additional research with more diverse participants to confirm these results across different populations.

Fish Oil: Potential Risks

The National Institutes of Health gives a recommended daily dietary intake (RDI) of 1,100 mg for women and 1,600 mg for men.

WebMD explains:

While fish oil supplements have generally been considered safe at recommended doses (around 3 grams daily), this study raises questions about their impact on heart health, particularly those without pre-existing cardiovascular conditions.

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Here are some general safety points to remember about fish oil supplements:

  • Dosage matters: Taking with daily consumption of more than 3 grams might increase their risk of bleeding.
  • Potential side effects: Common side effects include heartburn, loose stools, and nosebleeds. Taking fish oil with meals or freezing capsules can help minimize these.
  • Dietary sources vs. supplements: Consuming high amounts of fish from your diet (due to potential mercury and contaminant risks) differs from taking fish oil supplements, which are typically processed to remove these impurities.

Considering fish oil supplements, it’s wise to have an open conversation with your healthcare provider to determine if they’re right for you, given your health.

Be Careful With Other Medications

Fish oil supplements can interact with certain medications, so it’s important to be aware if you take any of these:

  • Blood thinners: Fish oil, like blood thinners (medications or supplements), can reduce blood clotting. Taking them together might increase your risk of bleeding.
  • Blood pressure medications: Fish oil might slightly lower blood pressure. If you take blood pressure meds already, combining them with fish oil could lead to your blood pressure dropping too low.
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  • Birth control pills: Some birth control pills might interfere with how fish oil affects your triglycerides (a type of fat in the blood).
  • Alli or Xenical (weight loss drugs): These medications might reduce your absorption of the beneficial fatty acids from fish oil. If you take both, consider taking them a few hours apart.
  • Vitamin E: Fish oil can lower your vitamin E levels. Talk to your doctor if you take both.

My Take

I don’t eat enough fish (even though I live in the Pacific Northwest of the United States), so taking supplements should help, right?

Not so fast, Michael.

The recent BMJ Medicine study throws a curveball into my thinking.

I must now consider that fish oil supplements might slightly increase my risk of suffering from a first-time heart attack or stroke.

Photo by Luca Micheli on Unsplash

Benefits Review

The study also hints that fish oil might offer protection against disease progression and even death for those already battling cardiovascular issues.

On the other hand,

Those without known cardiovascular disease might increase their relative risk of atrial fibrillation and stroke.

I have been using fish oil to lower my triglycerides (successfully, although I ramped up my exercise and improved my diet).

Now, I will get the omega-3s my body needs by eating reasonable amounts of oily fish. Broiled or baked, not fried.

I live in the Seattle area, after all.


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Michael Hunter, MD
Michael Hunter, MD
I received an undergraduate degree from Harvard, a medical degree from Yale, and trained in radiation oncology at the University of Pennsylvania. I practice radiation oncology in the Seattle area.

Michael Hunter, MD

I received an undergraduate degree from Harvard, a medical degree from Yale, and trained in radiation oncology at the University of Pennsylvania. I practice radiation oncology in the Seattle area.

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