Heart Health
Do Omega-3s Cause Heart Rhythm Disorders?
Omega-3 fatty acids are wrongly blamed for heart rhythm disorders. Recent scientific evidence shows they actually protect the heart.
Heart Health
Omega-3 fatty acids are wrongly blamed for heart rhythm disorders. Recent scientific evidence shows they actually protect the heart.
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We're receiving increasingly concerned emails about this. The question is: "I've read that omega-3 fatty acids can trigger heart rhythm disorders. What's the truth?"
Well, one could simply browse our blog and find the answer. [source no longer available]
We're talking specifically about one type of rhythm disorder: atrial fibrillation. Quite unpleasant. Fortunately, it doesn't just happen on its own.
Atrial fibrillation is a disease of aging. People over 80 show atrial fibrillation five times more often than middle-aged adults.
A variety of cardiovascular system disorders (high blood pressure, arteriosclerosis, cardiomyopathy, heart failure, heart valve defects, etc.) are closely linked to the onset of atrial fibrillation.
A variety of lifestyle factors are also associated with increased occurrence, such as overweight, too little movement (but also excessive), smoking, alcohol, thyroid disorders, and irregular sleep.
Put simply: you're not innocent. If it happens to you, it's very likely from an avoidable cause. It's not likely omega-3s.
But omega-3 isn't inherently associated with heart rhythm disorders. Just ten years ago, a study summary stated:
Marine omega-3 fatty acids can protect against heart rhythm disorders, and there is growing evidence of omega-3 fatty acids' effectiveness in preventing and treating atrial fibrillation.¹
Oh! Back then, the message was quite different.
Much knowledge at that time came from animal studies showing that omega-3 fatty acids had a pronounced protective effect on heart rhythm disorders, especially in the context of cardiovascular disease.²
This data seemed consistent with data from the Framingham Heart Study and the Physicians' Health Study, both concluding that omega-3 fatty acids substantially protect against (death from) cardiovascular disease.³,⁴
The widely cited REDUCE-IT Study also confirmed these protective effects. Over 8,000 high-risk patients received 4 g of EPA ethyl ester (more on this shortly).
The researchers promptly found a 25% reduced risk for death from cardiovascular disease, for non-fatal heart attacks and strokes, and other disorders.⁵
Unfortunately, the researchers also found a 35% higher occurrence of atrial fibrillation. In a meta-analysis examining several such human studies, scientists concluded that omega-3 fatty acids (over 1 g daily) were associated with a slightly increased risk of atrial fibrillation.⁶
But to understand this, you must know:
High omega-3 doses were often given in the studies. At doses of 3–4 g, omega-3 fatty acids significantly lower blood triglycerides. People hoped for beneficial effects on disease risk.
But without measuring omega-3 blood values (omega-3 index) beforehand, you're supplementing blindly. Additionally, ethyl esters are often given (see above). They lack their natural omega-3 spectrum. Moreover, they're in a chemically modified form that you don't consume through food or conventional fish oil.
Just last year, two more well-conducted studies were published. The crucial difference: measurements were taken.
The important Swiss Atrial Fibrillation cohort found no relationship between measured omega-3 fatty acid levels and atrial fibrillation occurrence. In fact, it showed that more omega-3 "calms" the heart and makes it beat slightly slower.⁷
Another large international study (55,000 participants) led by one of the world's most renowned omega-3 researchers – William S. Harris – (Fatty Acids and Outcomes Research Consortium), showed not only that omega-3 fatty acids aren't associated with atrial fibrillation, but also that they protect against it.⁸
This isn't usually reported. Instead, findings from a few publications circulate in the press and take on a life of their own.
We've come a long way. We've known for years that there's a global omega-3 deficiency. This can be definitively demonstrated with the omega-3 index. [source no longer available]
In omega-3-poor countries, omega-3 index values are around 4–5%. Particularly omega-3-rich countries, like Japan, show values >8. But that might only require 1–2 g of omega-3 daily, not 3–4 g.
Many people don't know: since the Physicians' Health Study, which showed that omega-3 fatty acids are the most important modifiable risk factor for sudden cardiac death, there's been a clear relationship between the omega-3 index and one of the most common causes of death from cardiovascular disease.
It's perhaps unsurprising, then, that sudden cardiac death – again: the most common cause of death from cardiovascular disease – occurs in Japan, by recent figures, 5.5 times less frequently than in Switzerland.⁹
Whoever stops taking omega-3 out of fear of minimal increased atrial fibrillation risk might be penny-wise and pound-foolish. Worth knowing.
