Fish oil supplements might not be as good for your heart as we once thought, a new study suggests. At least, not for everyone.
Numerous studies have shown that eating fish is associated with a reduced risk of dying from heart disease or stroke. However, whether these same benefits can be achieved through taking fish oil supplements is less conclusive. Even so, roughly one in 13 American adults takes fish oil supplements on a semiregular basis, according to surveys from the National Center for Complementary and Integrative Health.
Historically, the side effects of fish oil supplements have been considered to be fairly mild, including bad breath, headaches and stomach issues. But, according to new research, regular fish oil supplementation might actually be increasing our risk of the very thing they are purported to prevent.
The study, published in the journal BMJ Medicine, drew on data from 415,737 participants from the U.K. between the ages of 40 and 69, nearly a third of whom regularly took fish oil supplements.
Over an average 12-year monitoring period, those with no known cardiovascular disease at the start of the study who regularly took fish oil supplements were 13 percent more likely to develop atrial fibrillation—a condition that causes an abnormal heart rhythm and increases your risk of stroke—and 5 percent more likely to have a stroke than those who did not take the supplements.
However, among those who had already developed cardiovascular disease before the study period, regular fish oil supplements were associated with a 15 percent lower risk of progressing from atrial fibrillation to a heart attack, and a 9 percent lower risk of progressing from heart failure to death.
On further analysis, women and nonsmokers with no heart health concerns at the start of the study who took regular fish oil supplements were at the highest risk of suffering heart attacks, strokes and heart failure by the end of the study period, while men and older participants were more likely to see protective effects.
This study was, of course, purely observational so no causal relationships can be concluded from its findings. Secondly, while the researchers did account for certain confounding variables—like smoking, sex, fish consumption and age—other confounding variables may still exist.
Thirdly, the researchers did not have access to information on the doses and formulations of fish oil supplements used by the participants. However, their findings still highlight a need for further research in this area to confirm the effects of fish oil supplementation on the general population.
"Regular use of fish oil supplements might be a risk factor for atrial fibrillation and stroke among the general population, but could be beneficial for progression of cardiovascular disease from atrial fibrillation to major adverse cardiovascular events, and from atrial fibrillation to death," the authors write.
"Further studies are needed to determine the precise mechanisms for the development and prognosis of cardiovascular disease events with regular use of fish oil supplements."
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