Regular use of fish oil supplements could increase the risk of heart disease and stroke

Regular use of fish oil supplements may increase, rather than decrease, the risk of heart disease and stroke for the first time among those in good cardiovascular health, but it could slow the progression of existing poor cardiovascular health and reduce the risk of death, suggest the results of a large, long-term study, published in BMJ Medicine.

Contraindications for regular use of fish oil supplements

Fish oil is a rich source of omega 3 fatty acids and, as such, is recommended as a dietary preventative to ward off the development of cardiovascular disease. But the evidence on how much protection it offers is inconclusive, the researchers explain.

To strengthen the evidence base, they decided to estimate associations between fish oil supplements and new cases of atrial fibrillation; heart attack, stroke and heart failure; and death from any cause in subjects without known cardiovascular disease.

They evaluated the potential role of these supplements on the risk of progressing from good heart health (primary phase), to atrial fibrillation (secondary phase), to major cardiovascular events, such as a heart attack (tertiary phase), and death (terminal phase). .

They involved 415,737 UK Biobank Study participants (55% female), aged 40 to 69, who were interviewed between 2006 and 2010 to collect basic background information. This included their usual dietary intake of fatty and non-fatty fish and fish oil supplements.

Participants’ health was monitored until the end of March 2021 or death, whichever came first, using data from medical records.

Nearly a third (130,365; 31.5%) of participants said they regularly use fish oil supplements. This group included higher percentages of older adults, whites, and women. Alcohol consumption and the ratio of fatty to non-fatty fish consumed were also higher, while the proportions of current smokers and those living in deprived areas were lower.

During an average monitoring period of nearly 12 years, 18,367 participants developed atrial fibrillation, 22,636 had a heart attack/stroke or developed heart failure, and 22,140 died, including 14,902 without atrial fibrillation or serious cardiovascular disease.

Among those who transitioned from good cardiovascular health to atrial fibrillation, 3,085 developed heart failure, 1,180 had a stroke and 1,415 had a heart attack. And 2,436 of those with heart failure died, as did 2,088 of those who had had a stroke and 2,098 of those who had had a heart attack.

According to the findings, regular use of fish oil supplements had different roles in cardiovascular health, disease progression and death.

For those with no known cardiovascular disease at the start of the monitoring period, regular use of fish oil supplements was associated with a 13% increased risk of developing atrial fibrillation and a 5% increased risk of having a stroke.

Among those who had cardiovascular disease at the start of the monitoring period, regular use of fish oil supplements was associated with a 15% lower risk of progressing from atrial fibrillation to a heart attack and a 9% lower risk of progressing from heart failure. to death.

Further in-depth analyzes revealed that age, sex, smoking, consumption of non-oily fish, hypertension, and use of statins and hypotensive drugs modified the observed associations.

Regular use of fish oil supplements and the risk of going from good health to heart attack, stroke or heart failure were 6% higher in women and 6% higher in nonsmokers. The protective effect of these supplements on the transition from good health to death was greatest in men (7% lower risk) and in older participants (11% lower risk).

Because this is an observational study, it is not possible to draw conclusions about causal factors, the researchers acknowledge. No potentially influential information was available on either the dose or formulation of fish oil supplements. And because most of the participants were white, the findings may not apply to people of other ethnicities, the researchers add.

But they conclude: “Regular use of fish oil supplements could have different roles in the progression of cardiovascular disease. 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.”

Fish oil supplements linked to heart rhythm disorders

Omega-3 supplements are associated with a greater chance of developing atrial fibrillation in people with high blood lipid levels. This is the result of a study published in the European Heart Journal—Cardiovascular Pharmacotherapy, a journal of the European Society of Cardiology (ESC).

“Currently, fish oil supplements are indicated for patients with elevated plasma triglycerides to reduce cardiovascular risk,” said study author Dr Salvatore Carbone of Virginia Commonwealth University, USA. “Due to the high prevalence of elevated triglycerides in the population, they may commonly be of note. Low-dose omega-3 fatty acids are available over the counter, without the need for a prescription.”

Some clinical studies have suggested that omega-3 fatty acids may be associated with an increased risk of atrial fibrillation, the most common heart rhythm disorder. People with this disorder are five times more likely to have a stroke.

These studies tested different formulations of omega-3 fatty acids at different doses. The authors then performed a comprehensive meta-analysis of randomized, controlled trials to answer the question of whether fish oils were consistently related to an increased risk of atrial fibrillation.

The analysis included five randomized, controlled trials that evaluated the effects of omega-3 fatty acid supplementation on cardiovascular outcomes. Participants had elevated triglycerides and were at high risk for cardiovascular disease or had established cardiovascular disease. A total of 50,277 patients received fish oils or placebo and were followed for 2 to 7.4 years. The dose of fish oils ranged from 0.84 g to 4 g per day.

The researchers found that omega-3 fatty acid supplementation was associated with a significantly greater risk of atrial fibrillation compared to placebo with an incidence ratio of 1.37 (95% confidence interval 1.22-1.54 ; p<0.001).

Dr Carbone said: “Our study suggests that fish oil supplements are associated with a significantly increased risk of atrial fibrillation in patients at high cardiovascular risk.

Although a clinical trial indicated beneficial cardiovascular effects of supplementation, the risk of atrial fibrillation should be considered when such agents are prescribed or purchased over the counter, especially in individuals susceptible to developing heart rhythm disorders.”

Vitamin D and fish oil do not reduce the risk of atrial fibrillation

A study published in JAMA (Journal of the American Medical Association) confirms that neither vitamin D nor the omega-3 fatty acids found in fish oil prevent the development of atrial fibrillation (AF), a potentially serious heart rhythm disorder. The newly released research follows a presentation made by Christine Albert, MD, MPH, at the American Heart Association Scientific Sessions.

In their JAMA analysis, Albert and his research team also looked at whether vitamin D or omega-3 fatty acids might have an impact on paroxysmal versus persistent atrial fibrillation, and whether there might be certain subgroups of patients who would be more likely to to benefit or be harmed. from supplements. Overall, the results were mostly consistent across AF types and patient groups.

“Our recommendation remains the same,” said Albert, chair of the Department of Cardiology at the Smidt Heart Institute and the Lee and Harold Kapelovitz Distinguished Chair in Cardiology. “We do not support taking fish oil or vitamin D supplements to prevent atrial fibrillation.”

Albert added: “However, unlike other recent studies that have found an increased risk of atrial fibrillation with higher doses of omega-3 fatty acid supplements, our study did not find a significant increase in the risk of atrial fibrillation with one gram of fish oil per day, which is good news for people taking low-dose fish oil for other health problems.”

Albert added: “However, unlike other recent studies that have found an increased risk of atrial fibrillation with higher doses of omega-3 fatty acid supplements, our study did not find a significant increase in the risk of atrial fibrillation with one gram of fish oil per day, which is good news for people taking low-dose fish oil for other health problems.”

Similarly, vitamin D supplements of 2,000 international units per day also did not increase the risk of atrial fibrillation.

Atrial fibrillation, commonly called Afib, is the most common type of abnormal heart rhythm, causing the heart to contract irregularly and sometimes too quickly. It is estimated to affect 33 million people worldwide.

The condition can lead to the formation of clots within the atrium chamber of the heart and the clots can then travel from the heart to the brain, causing a stroke. Atrial fibrillation can also lead to weakening of the lower chamber of the heart, resulting in fluid buildup or heart failure. Importantly, it often causes significant symptoms that can negatively impact your quality of life.