Norman Swan: A high proportion of people aged 45 and over in Australia take fish oil supplements. They have been touted for improving mood, reducing inflammation, and protecting your heart. However, over time and the publication of better designed studies, the evidence of the benefits of fish oil supplements has weakened. On the last day, a study was published internationally that looked at whether omega-3 fatty acids, believed to be the active constituents of fish oil, protect people at high risk of heart attacks and strokes. However, the results were disappointing. The lead author was Professor Stephen Nicholls, director of MonashHeart and the Victorian Heart Institute. Welcome to the health report, Stephen.
Stephen Nicholls: Thank you.
Norman Swan: Tell us about the people who have studied.
Stephen Nicholls: So we looked at people who were at high risk of a heart attack or stroke. So these were people who either had a previous heart attack or stroke, or had some sort of stenting or bypass procedure, or people who we considered high-risk primary prevention, were people who either had diabetes or a Combination of several risk factors that we believed to be at high risk for a clinical event. In addition, it was important that these people have evidence of high triglycerides and low levels of what we call HDL cholesterol, the good form of cholesterol …
Norman Swan: Why was that?
Stephen Nicholls: Well, because we knew that in patients in clinical trials where we had previously shown the benefits of statins, the drugs commonly used to lower the bad form of cholesterol and prevent heart attacks and strokes in large clinical trials, We Know That In those studies where triglyceride levels were high and HDL cholesterol levels were low, these patients were still at very high risk … still high risk of a heart attack or stroke even if they were treated with a statin.
Norman Swan: We just have to decipher that very quickly. So triglycerides are another form of fat in your blood, and they actually make the low-density lipoprotein more toxic if you want, and the high-density lipoprotein has a protective effect, but statins don’t affect any of these, you ‘we have to somehow lose weight, lose your belly fat, to affect your triglycerides. You need to do more exercise to increase your HDL.
Stephen Nicholls: They do, and we have many patients in our clinic on statins. We are able to lower their bad cholesterol, but these other lipid abnormalities are still there and present us with a huge challenge in a day in the clinic. today’s basis.
Norman Swan: So you were hoping that adding the omega-3 fatty acids could fix that.
Stephen Nicholls: Well, it was us, and as you said, this has been a controversial area for decades. Early population studies suggested that fish oil should be protective. And then we saw a lot of clinical studies with relatively low doses of omega-3 fatty acids, and none of them worked. And over time, looking at these studies, some of us thought that this could likely be a function of the dose of omega-3 fatty acids, as you need to be able to take doses high enough to get that Levels of omega-3 acids in the tissues like the heart muscle and blood vessels actually increase in order to be able to get the benefit. More recent clinical studies have therefore attempted to investigate the effects of administering extremely high doses of omega-3 fatty acids.
Norman Swan: And you’ve used the combination of the two that are supposed to be effective, namely EPA and DHA.
Stephen Nicholls: We did, and that’s how we knew there were already two large studies using EPA only. Both had reported benefits. We wanted to see if the combination of EPA and DHA, again in a high dose, was protective. And again, the population studies would have suggested that this should be the case.
Norman Swan: And when you buy commercial preparations of omega-3 fatty acids, do they both traditionally?
Stephen Nicholls: You can buy purified versions of both, but the other important thing to note is that almost all of the preparations you can buy over the counter are actually very low in omega-3 fatty acids. So the results of these studies have implications for public health.
Norman Swan: Indeed. We won’t be running out of time anytime soon, but you’ve been looking to see if people have died of heart disease, if they have had a non-fatal heart attack, a non-fatal stroke, or if they need a stent or bypass.
Stephen Nicholls: It is so, and we have done a study with 13,000 patients in 22 countries, we have shown absolutely no benefit. In addition, we saw some safety issues, gastrointestinal intolerance, abdominal pain and diarrhea, and an increased risk of atrial fibrillation, a very common heart rhythm disorder that can be linked to a higher risk of stroke in the long term.
Norman Swan: Why should you be at higher risk for atrial fibrillation? So that’s more in the active group than in the placebo group?
Stephen Nicholls: That is correct, and this is a really interesting observation, because for many years researchers in the fish oil room have been wondering whether they actually have a protective effect on the heart rhythm because they can get into cell membranes and stabilize these membranes. But what we’ve seen now, not just our clinical study, but other clinical studies in this area have shown that omega-3 fatty acids increase the rate of atrial fibrillation.
Norman Swan: Well, isn’t that interesting because you would know you run a cardiac institute, but there is almost an epidemic of atrial fibrillation right now. Do you think it is causing fish oil?
Stephen Nicholls: Well, we don’t think the fish oil is causing the atrial fibrillation epidemic that we are seeing, but we certainly don’t need any additional factors as atrial fibrillation is a sufficient challenge for us in the clinic. And again, like I said, it really turned the whole field upside down because at first we thought they should be beneficial to the heart rhythm, but they have an adverse effect and that has potentially big ramifications when you think about it all the various reasons people might take a fish oil. It can only be for knee pain. You suddenly have a man in his seventies with some osteoarthritis who takes fish oil to relieve his knee pain and who suddenly has a higher risk of atrial fibrillation. We think there are important messages there.
Norman Swan: Is the message “Save your money”?
Stephen Nicholls: I think it will save your money over-the-counter. The other thing I keep telling all of my patients who spend a lot of money on over-the-counter fish oils is to speak to their doctor and understand why you are using the fish oil. If you are taking the fish oil to avoid a heart attack, it is the wrong reason to take it. You may have other reasons for taking it. But I think whether you have been prescribed a drug or whether you are buying something over the counter from a pharmacy, I think it is always good advice to discuss this with your GP.
Norman Swan: General practitioners will not necessarily know the results of this study, however, and 45% of their patients over 45 are using fish oil.
Stephen Nicholls: They are, and so I think our ability to communicate the results of studies is important and that it is challenging, whether or not studies show drugs work. I think we need to find better ways to get this message across.
Norman Swan: Stephen, thank you very much.
Stephen Nicholls: Thank you.
Norman Swan: Professor Stephen Nicholls at the Victorian Heart Institute at Monash University. And you can chat with your GP and refer them to the health report.