- New research has found that common types of fish oils may not be as beneficial to the heart as they were thought to be.
- The study found that high doses of omega-3 fatty acids did not reduce the likelihood of a serious cardiovascular event.
- About 6 percent of people who took fish oil had atrial fibrillation or irregular heartbeat.
New research from the Cleveland Clinic has found that common types of fish oils may not be as beneficial to the heart as they were previously thought.
The study, published Nov. 15 in the Journal of the American Medical Association, found that high doses of omega-3 fatty acids did not reduce people’s chances of having a serious cardiovascular event.
The evidence for using fish oil for heart health is mixed. Often times, the type of fish oil and the type of placebo used will affect the results.
Heart doctors suggest that different types of fish oils – particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) – have different effects on the body.
More research is needed to better understand how the different types affect the cardiovascular system.
“For patients searching for answers to fish oil, the current data supports purified EPA fish oil Vascepa as opposed to over-the-counter fish oil, low-dose fish oil, and a combination of DHA and EPA fish oil. More studies are needed to compare purified EPA fish oil versus a neutral corn oil placebo or other formulations of DHA and EPA fish oils versus purified EPA fish oil, ”Dr. Guy Mintz, director of cardiovascular health and cardiology lipidology at Northwell Health’s Sandra Atlas Bass Heart Hospital in Manhasset, New York, told Healthline.
In the randomized clinical study, 13,078 people received either daily supplementation with high-dose omega-3 fatty acids from DHA and EPA or a placebo from corn oil.
Patients were already on statins (medicines used to lower cholesterol) and were previously diagnosed with high cardiovascular risk, hypertriglyceridemia, or low levels of high-density lipoprotein cholesterol.
The study was stopped prematurely because there was no significant difference between the two groups.
In addition, about 67 percent of the participants who took the fish oil supplements had atrial fibrillation (irregular heartbeat), suggesting an increased risk associated with supplements that contain both EPA and DHA fatty acids.
Consequently, the researchers do not recommend the EPA-DHA-omega-3 fatty acid formulation for reducing cardiovascular events.
“The combination of DHA and EPA fish oil showed no significant cardiovascular benefit even at high dosages, and especially in this study – the STRENGTH study,” says Mintz.
According to Mintz, fish oil is widely recognized as beneficial to health because of its anti-inflammatory properties, blood-thinning properties, and improving triglyceride levels.
But much of the evidence for fish oil has been mixed.
Previous studies looked at different amounts of fish oil and types of placebo (e.g. corn oil or mineral oil). They also rated various fish oil compositions.
These differences make it difficult to compare all the results, according to Dr. Sanjiv Patel, an interventional cardiologist at the MemorialCare Heart & Vascular Institute at the Orange Coast Medical Center in Fountain Valley, California.
It is also likely why the results were different.
For example, one study, the REDUCE-IT study, tested EPA supplements (without DHA) along with a mineral oil placebo and found that the omega-3s had significant benefits for heart health.
However, the mineral oil placebo is believed to have had deleterious effects on the cardiovascular system – such as an increase in LDL cholesterol.
Some experts suggest that this could have made the fish oil appear more useful than it actually was.
“Theoretically, mineral oil could do harm, and if the effects of fish oil were neutral, comparing the two would lead to the misleading impression that fish oil helps prevent poor results,” says Dr. Richard Wright, cardiologist at The Providence Saint John Health Center in Santa Monica, California.
Other studies have assessed DHA or EPA separately and mixed in different amounts. In some studies, DHA has been linked to increases in LDL cholesterol, says Mintz.
“As stated in the publication, there is a possibility that the cause of the discrepancies in the results of these various studies is that a mixed preparation of omega-3 fatty acids (commonly referred to as fish oil) was most commonly used, including the current one Study, ”said Wright.
No studies have convincingly shown that popular over-the-counter fish oils result in clinical benefit, Wright added.
Future studies need to evaluate the benefits of fish oil, which contains purified EPA rather than DHA, according to Mintz.
Most heart doctors agree that over-the-counter fish oil products, low-dose fish oil, and combined DHA and EPA supplements offer no benefit.
Some data supports the use of purified prescription fish oil, according to Mintz.
Overall, however, the evidence is unclear.
If you are considering taking fish oil for your heart health, it is important to consult a doctor first.
“Given the slight increase in atrial fibrillation with the use of fish oil, one conclusion is clear, patients should always discuss the use of this dietary supplement, as well as any other, with their doctor,” said Patel.
New research from the Cleveland Clinic has shown that fish oil may not be as beneficial to the heart as it was previously thought. According to the study, high doses of common fish oils did not reduce the risk of a cardiovascular event.
Much of the evidence for fish oil is mixed and varies based on the type and amount of fish oils evaluated, as well as the type of placebo used. More research is needed to understand how different types of fish oils affect the body.