There are a number of main risk factors for stroke you can avoid through a healthy diet. (Image: GETTY)

As an excellent source of heart-healthy omega-3 fatty acids, daily fish oil supplements are a popular way to keep the risk of cardiovascular disease at bay.

About 20% of adults older than age 60 in the United States frequently use these products with the aim of supporting heart health.

However, a new study finds regular use of fish oil supplements may increase, not reduce, the risk of first-time stroke and atrial fibrillation among people in good cardiovascular health.

Atrial fibrillation, also called AFib or AF, is a type of arrhythmia, or irregular heartbeat, that people often describe as a flutter or pounding in their chests.

“I can see the headline for this study as ‘Fish oil supplements: Is it time to dump them or not?’” said cardiologist Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver.

“I say that because over-the-counter fish oil is very seldom recommended, is in none of the guidelines from professional medical societies, and yet that’s what most people take,” said Freeman, who was not involved in the study.


Fish oil only helped people with existing heart disease

The study analyzed data on over 415,000 people ages 40 to 69 participating in the UK Biobank, a longitudinal study of the health of people in the United Kingdom. Nearly one-third of those people, who were followed for an average of 12 years, said they regularly used fish oil supplements.

For people without heart issues, regular use of fish oil supplements was associated with a 13% higher risk of developing atrial fibrillation and a 5% heightened risk of having a stroke, according to the study, published Tuesday in the journal BMJ Medicine.

Over-the-counter fish oil suffers from a lack of purity and consistency, as well as the potential contaminants and heavy metals such as mercury that come with fish, Freeman said.

“Overall, I would say that the days where people just go to the store and buy buckets of fish oil pills to keep them well should be over, but fish oil may still have a role in people who are already sick.”

Fish oil may help with certain heart conditions, but should only be taken after discussing with a doctor, experts say.

Try to use food sources for omega-3s

When it comes to fish oil, “the devil is in the details,” said Alzheimer’s preventive neurologist Dr. Richard Isaacson, director of research at the Institute for Neurodegenerative Diseases in Boca Raton, Florida. He was not involved in the study.

“First, we recommend testing for omega-3 fatty acid levels — there are finger-prick tests you can buy online which are accurate — and then you should continue to test. You don’t want to take fish oil if you don’t need it,” he said.

Isaacson recommends trying to get your omega-3 fatty acids from food sources and says sardines and wild-caught salmon are the best sources, as they are high in these healthy unsaturated fats and lower in mercury. Farm-raised salmon is not the best choice, he said, due to impurities in the water in which they are raised.

Lake trout, mackerel, herring and albacore tuna are also good sources, he said. However, due to the mercury levels in large fish such as tuna, he recommends consumption of albacore tuna should be kept to twice a week.

Algae and seaweed are decent nonfish sources of omega 3s as well. Chia seeds, edamame (soy beans), flaxseed, hempseeds and walnuts are other plant-based options that are high in omega-3s. But the fatty acids are a different form than those found in fish. Studies have found plant-based omega-3s may be harder to metabolize in people with higher levels of omega-6s, another kind of unsaturated fats that’s found primarily in vegetable oils.

If supplements are needed

Prescription omega-3 fatty acids are superior to over-the counter options, experts say, due to their pureness and quality. But prescribed supplements can be expensive. For people who decide they want to purchase over-the-counter omega-3s, Isaacson provides these tips to his patients.

First, freshness of the fish oil is key, he said, adding that “buying from an online or retail superstore, such as Amazon or Costco, isn’t the best idea.”

Results from both clinical trials were to be presented Saturday at the American Heart Association’s annual meeting, in Chicago, and published simultaneously in the New England Journal of Medicine.

For the VITAL trial, nearly 26,000 U.S. men and women aged 50 and older were randomly assigned to take 1 gram of fish oil or 2,000 International Units of vitamin D daily, or a placebo. Participants had no history of heart problems.

The fish oil supplements reduced risk of heart attack by 28 percent over a five-year follow-up period, but they did not affect a person’s risk of stroke or cancer, researchers found.

“The lower risk of heart attack was found particularly in those who have low fish consumption,” Manson said. “That group had 19 percent reduction in all major cardiovascular events, plus they had a 40 percent reduction in heart attack.”

VITAL also found overwhelming benefit of fish oil supplements for black participants, who had a 77 percent reduction in their risk of heart attack.

“If that can be confirmed in a follow-up study, then it could point to a very promising approach to reducing a health disparity,” Manson said. Blacks tend to have a greater risk of heart disease than whites and other racial groups.

The clinical trial found no heart health benefit from vitamin D, although it did reduce the risk of cancer death by 25 percent.

Dr. Satjit Bhusri is a cardiologist with Lenox Hill Hospital in New York City. “This is a very important and impressive trial. Its results will have a lasting change in the prevention of heart disease,” said Bhusri, who was not involved with the studies. “A reduction in heart attacks this profound has not seen been since in primary prevention since the early trials of aspirin therapy.”

In the REDUCE-IT trial, another research team at Brigham and Women’s Hospital tested the benefits of a pure and stable form of the omega-3 fatty acid known as EPA.

The supplement, icosapent ethyl, is a prescription medication approved to reduce triglyceride levels in people with high cholesterol.

REDUCE-IT included more than 8,000 patients taking statins to lower their cholesterol and prevent either a first or repeat heart attack or stroke. About 7 in 10 patients in the study had hardened arteries, while the rest had diabetes and at least one other heart risk factor.

People taking icosapent ethyl had a 20 percent reduction in their risk of heart-related death, a 31 percent reduction in heart attack and a 28 percent reduction in stroke, compared to those given a placebo, researchers found.

“The REDUCE-IT trial sets a new standard of care for patients who have elevated triglycerides and are at increased cardiovascular risk despite statin therapy,” lead researcher Dr. Deepak Bhatt, executive director of interventional cardiovascular programs at Brigham and Women’s Hospital, said in hospital news release. “This may be the biggest development in cardiovascular prevention since statins.”

There are many ways that omega-3 fatty acids could help heart health, Manson said. They are known to lower triglyceride levels, reduce inflammation, decrease blood clotting and help stabilize heart rhythm.

People interested in taking fish oil supplements should discuss it with their doctor first, said Dr. Helene Glassberg, an associate professor of clinical cardiovascular medicine at the University of Pennsylvania’s Penn Medicine. She was not involved with the studies.

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