Everything you need to know about fish oil supplements

The woman is Holding omega-3 fish oil capsules or medications, and a glass of water. Healthy lifestyle, prevention and treatment of diseases. The girl Takes and Drinks food supplements and vitamins. Biologically active additive. Intake of healthy fats.
Fish oil supplements are widely consumed, but new research shows they might not be as good for our heart health as previously thought. (Getty Images)

In the world of supplements, fish oil has been around for a long time. These dietary supplements are usually sold as sources of omega-3 fatty acids which can be very beneficial to our health.

One of the biggest claims of fish oil supplement manufacturers and brands is that they are good for maintaining good cardiovascular health. However, this claim has been at the centre of controversy in recent years.

A new study carried out by researchers in China, the US, the UK and Denmark found that fish oil supplements could increase the risk of a person with no known cardiovascular disease developing a heart condition or stroke.

The researchers monitored the health of over 400,000 participants in the UK Biobank for an average of 12 years, with the aim of analysing links between fish oil supplements and new cases of irregular heartbeat, heart attack, stroke, and heart failure.

The results come after a 2018 review found little evidence that fish oil supplements can prevent heart disease. The researchers examined trials in over 100,000 people and said the studies "consistently showed little or no effect of long-chain omega-3 fats on cardiovascular health".

Cochrane lead author Dr Lee Hooper, from the University of East Anglia, told the BBC at the time: "The review provides good evidence that taking long-chain omega-3 supplements does not benefit heart health or reduce our risk of stroke or death from any cause."

Close-up young woman taking a Fish Oil Omega-3 capsule at home, Healthy lifestyle in prevention and treatment of diseases. Woman takes and drinks food dietary supplements and vitamins
A study suggests that taking fish oil supplements may increase the risk of developing heart conditions in people who don't have any cardiovascular issues. (Getty Images)

A 2023 study carried out in the US also found that many claims made by fish oil companies are "untested" and not backed up by clinical trial data.

In the most recent study, which was published last week in the journal BMJ Medicine, participants with no known cardiovascular disease were found to have a 13% higher risk of developing atrial fibrillation (irregular heartbeat) and a 5% increased risk of having a stroke with regular consumption of fish oil supplements.

However, the study did show there was some benefit to taking the supplements in patients who had heart disease at the beginning of the study. These patients who took fish oil supplements regularly were associated with a 15% lower risk of going from atrial fibrillation to a heart attack, as well as a 9% lower risk of going from heart failure to death.

capsules with fish oil from cod liver in the shape of a fish on a white background
Fish oil supplements are very popular, but could eating oily fish be more beneficial? (Getty Images)

As the study is observational, the authors have cautioned that no conclusions can be drawn about what is directly causing the heightened risk of heart disease in healthy participants.

However, NHS GP Dr Anita Raja based in Birmingham, tells Yahoo UK that she would be inclined to follow advice given by the British Cardiovascular Society.

"The British Cardiovascular Society has suggested the following: ‘There is currently insufficient evidence to conclude whether omega-3 fatty acid supplementation reduces cardiovascular risk in patients already deemed to be at high risk. Therefore, I would not advocate that these patients are routinely recommended to take omega-3 supplements.’

"I would certainly consider giving the same advice to my own patients given the current lack of concrete evidence around the benefits of regularly taking omega-3-supplements."

Tracy Parker, a senior dietitian at the British Heart Foundation, added to the Guardian that while the research shouldn’t be a source of worry for people who currently take fish oil supplements regularly, it is "not a green light to start taking them to prevent heart and circulatory diseases".

“"n the UK, Nice guidelines don’t recommend taking fish oil supplements to either prevent heart and circulatory diseases or stop another heart attack.

"Supplements such as omega-3 fatty acids are no substitute for a healthy diet and, instead of focusing on individual nutrients, it’s important to look at your diet as a whole to help lower your risk."

mackerel in tinned canned goods
Photo of canned fish in tomato sauce
Eating oily fish is recommended as part of a healthy diet. (Getty Images)

The British Heart Foundation does not recommend consuming fish oil supplements, adding that "it seems any benefits of fish oils comes from eating the fish rather than in a supplement form".

Oily fish such as herring, salmon, sardines, trout, and mackerel are widely considered an important source of omega-3 fatty acids and vitamin D.

The NHS recommends eating at least two portions of fish a week, including one portion of oily fish, as part of a healthy and balanced diet. Eating fish that is steamed, baked or grilled is a healthier choice compared to fish that is fried, the NHS states.

Dr Raja adds: "The rule of thumb should always be to implement a healthier diet rather than need for oral supplementation. Oily fish is a great natural source of vitamin D, protein and omega 3 fatty acids.

"Diet and nutrition have a significant influence on our cardiac health and overall wellbeing. Our cardiovascular risk can only be reduced if we avoid trans fats & high carbohydrate diets. Portion control, organic food, vegetables and fruits rather than last minute takeaways would be a great way to ensure a healthier cardiovascular health."

Exercise is also key to staying healthy, Dr Raja says, pointing out that Caucasians should maintain a BMI (Body Mass Index) of less than 25 and South Asians should maintain a BMI of less than 23.

"Regular exercise at least 3 times per week for 30-45 mins at a high pace to bring up your heart rate will assist in managing a healthy lifestyle."

However, if you do want to incorporate supplements into your everyday diet, the British Dietetic Association advises:

  • Choose omega-3 rather than fish liver oil

  • Check the vitamin A content (you should not have more than a total of 1.5mg of vitamin A a day from food and supplements combined)

  • Do not take supplements containing vitamin A if you are pregnant or planning to become pregnant

  • Check labels for DHA and EPA content

  • Choose a supplement that provides you with the same daily amount provided by eating one to two portions of fish per week (about 450mg per daily adult dose)

  • Choose an age-appropriate supplement

  • Seek advice from a dietitian if in doubt

Watch: New study questions science behind fish oil supplements

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