- New research has found that common types of fish oil may not be as beneficial to the heart as was thought.
- The study found that high doses of omega-3 fatty acids did not reduce the likelihood of a serious cardiovascular event in humans.
- 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 oil may no longer be as beneficial to the heart as was previously thought.
The study, published November 15 in the Journal of the American Medical Association, found that high doses of omega-3 fatty acids did not reduce the likelihood of a serious cardiovascular event.
The evidence on the use of 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 fishing for fish oil responses, the current data supports purified EPA purified prescription fish oil Vascepa as opposed to over-the-counter fish oil, low dose fish oil, and a combination of DHA and EPA fish oil. Further 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, ”said 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 a daily supplement with high-dose omega-3 fatty acids from DHA and EPA or a placebo from corn oil.
Patients were already taking statins (drugs that lower cholesterol) and had previously been diagnosed with high cardiovascular risk, hypertriglyceridemia, or low high-density lipoprotein cholesterol.
The study was interrupted prematurely because there was no significant difference between the two groups.
Additionally, about 67 percent of participants who took fish oil supplements had atrial fibrillation (irregular heartbeat), which indicates that there is an increased risk 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 – STRENGTH study -” says Mintz.
According to Mintz, fish oil is widely believed to improve heart health due to its anti-inflammatory properties, blood-thinning properties, and triglyceride levels improvement.
But much of the evidence for fish oil is mixed.
Previous studies looked at different amounts of fish oil and types of placebos (such as corn oil or mineral oil). They also rated various fish oil compositions.
These differences make it, according to Dr. Sanjiv Patel, an interventional cardiologist at the MemorialCare Heart & Vascular Institute at Orange Coast Medical Center in Fountain Valley, California, found it difficult to compare all the results.
It is also likely why the results were different.
For example, in one study, the REDUCE-IT study, EPA supplements (without DHA) were tested alongside a mineral oil placebo and found that the omega-3 fatty acids had a significant benefit for heart health.
However, the mineral oil placebo is believed to have had deleterious effects – such as an increase in LDL cholesterol – on the cardiovascular system.
Some experts suggest that this may have made the fish oil appear more beneficial than it actually was.
“Mineral oil could theoretically do harm, and if the effects of fish oil were neutral, trying to compare the two would give the false 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 still a possibility that the root of the discrepancies in the results of these various experiments is that a mixed preparation of omega-3 fatty acids (commonly referred to as fish oil) was most commonly used, too in the current study, “Wright said.
No study has convincingly shown that common over-the-counter fish oils lead to 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 are of 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 when using fish oil, one conclusion is clear: patients should always discuss the use of this and other supplements with their doctor,” said Patel.
New research from the Cleveland Clinic has shown that fish oil may no longer be as beneficial to the heart as 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 depends on the type and amount of fish oils evaluated and the type of placebo used. More research is needed to understand how different types of fish oils affect the body.