ZOE Science & Nutrition - Omega-3 supplements: why you're (probably) wasting your money

Episode Date: May 4, 2023

“Omega 3s,” - we’ve all seen the name Omega 3s advertised on labels from nuts to seeds and even eggs! But are these fats healthy for us, or is this just another food myth? In today’s short episode of ZOE Science & Nutrition, Jonathan and Sarah ask: Is fish oil and omega 3 intake essential or is this just another food myth? Follow ZOE on Instagram: https://www.instagram.com/zoe/ Download our FREE guide — Top 10 Tips to Live Healthier: https://zoe.com/freeguide Studies referenced in the episode: High-fat meals rich in EPA plus DHA compared with DHA only have differential effects on postprandial lipemia and plasma 8-isoprostane F2α concentrations relative to a control high–oleic acid meal: a randomized controlled trial Intake of fish and marine n-3 polyunsaturated fatty acids and risk of cardiovascular disease mortality: A meta-analysis of prospective cohort studies Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease The 3 most Important Types of Omega-3 Fatty Acids REDUCE-IT EPA trial shows association between higher EPA levels, reduced CV events  Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: Results of the GISSI-Prevenzione trial Omega-3 Fatty Acids for the Management of Hypertriglyceridemia: A Science Advisory From the American Heart Association Episode transcripts are available here. Is there a nutrition topic you’d like us to cover? Email us at [e-mail] and we’ll do our best to cover it.

Hello and welcome to Zoe Shorts, the Bite Size podcast where we discuss one topic around science and nutrition. I'm Jonathan Wolfe and today I'm joined by Dr. Sarah Berry and today's subject is omega-3 and oily fish. So Jonathan, increasing oily fish and omega-3 in our diet is often advised as a simple way to protect your heart health. But in recent years, people have questioned whether omega-3 is really as effective as we once believed. So Sarah, should we be focused on increasing our intake of oily fish, or is this just yet again a food myth? Well, it's actually quite a divisive subject,

Jonathan, and I have quite a clear opinion opinion and yet this is one of those topics where there's other scientists I respect who probably disagree with me. How exciting! Well let's get into it. So Sarah I see all sorts of ads for products rich in omega-3. I also see a lot of ads for fish oil supplements and it's actually so popular apparently that of ads for fish oil supplements. And it's actually so popular, apparently, that in the US, fish oil capsules are the most commonly taken supplement, both for adults and for children. And globally, the industry is believed to be worth around $30 billion. But what exactly is omega-3? So omega-3 is a type of fat. We often refer to omega-3 as an essential fatty acid. and this is because unlike many other types of fats our bodies actually can't make it yet it's really vital for our health and

therefore it's essential that we consume it in our diet and the term omega-3 actually comes from where something called a double bond is actually positioned in the fat and humans can't insert double bonds into the position three of the fat when we make fats in our liver. And this is why it's essential that we consume it in our diet. Now, as I know from the advertising that you see at the fish counter, oily fish like mackerel and salmon and anchovies are supposed to be this great source of omega-3. Is this true, Sarah? It is true. And this is also where the fish oil capsules you mentioned

come in. And I imagine there's lots of people in our audience who are familiar with these supplements. They can come in liquid, capsule and pill form. And so Sarah, what are the health benefits of omega 3 and oily fish and these oily fish capsules? So omega 3 and oily fish have been associated with a whole host of health benefits. So for example, it's been linked to reduce inflammation, it's been linked to reduce risk of heart disease, and a lot of areas around brain health as well. So improved memory, improved alertness, lower depression, and also related to gut health. So for example, improved conditions for people with irritable bowel disease.

So that all sounds pretty great. I mean, who wouldn't want to take a little capsule to make all of those things better? There is one thing I want to ask because you said omega-3 is an essential fatty acid. I know lots of people who don't eat any fish at all and yet they're still alive. So I presume you can get this omega-3 from other sources than these oily fish? Yeah, so there's several types of omega-3 fatty acids. The three most important ones are alpha-linolenic acid, which we also call ALA, which is found mainly in plant products, so nuts and seeds, for example. Then there's EPA and DHA, also known as eicosapentaenoic and decosahexaenoic acid, which we find in oily fish in really large amounts, and also in very small amounts in eggs and dairy.

Now, both EPA and DHA are the ones that have really important roles in the membranes of our cells. And so because of this, they have really wide-reaching roles throughout our bodies. DHA is found in particularly high concentrations in our brain and our eyes, and therefore it's especially important in our vision and also in the brain development, particularly of newborns. Does that mean that although these other things you say have these special effects, actually, if you just are getting the first one you mentioned, I think you said ALA from plants, that does give you this essential fatty acid that allows you to make your brain and your eyes and all of these sorts of things and support them?

So it's the DHA and EPA that's particularly important in vision, in brain development, and in producing these very special chemicals that are associated with heart health. However, what's quite clever is our bodies can convert a small amount of this ALA that comes from plant-based foods into these really long chain EPA and DHA fats. The problem is, is we actually can't convert much. So it's estimated on average, we might convert about 10% of ALA into EPA and DHA. And this is why some people recommend that vegetarians or vegans might also want to consider having a supplement of this very long chain EPA and DHA fats. Brilliant. Well, I think it seems pretty clear that there's a potential for lots of benefits. So why could this be causing division even amongst the scientists

who are, for example, closely involved here at Zoe? So I think firstly, we need to look at the evidence for the health effects of oily fish separately from the evidence for the health effects of omega-3. And then I think we also need to recognise how the studies researching the effects of omega-3 have changed over the past few decades, which I believe to be the root of the inconsistency in the evidence and therefore much of the division of the opinion at ZOE around omega-3. Brilliant. So what's the evidence around oily fish? So the evidence from studying fish intakes in populations, so we mean epidemiological evidence here, is really consistent in my opinion that oily fish consumption is very clearly associated with reduced risk of

cardiovascular disease and mortality from cardiovascular disease. And this is particularly strong in those who've already had cardiovascular disease. So what we see is for about every 20 gram increase in oily fish a day, this is associated with a 4% reduction in cardiovascular disease. And what we also see from some of these really big studies is if people are having no oily fish versus those that are having two or more oily fish portions a week, you can see actually an 80% reduction in the risk of cardiovascular disease. And this is huge. Now, there's also been some studies that have concluded that the effects of fish oil supplements are really small when it comes to cardiovascular disease and also mortality rates. The most significant research I think that people often talk about came from a meta-analysis

of 37 clinical trials. So this is basically a study that looked at all of the data from 37 different clinical trials. And this was including, therefore, hundreds of thousands of participants. And this research found that increasing the EPA and DHA omega-3 provided very little, if any, benefit on most of the health outcomes that they looked at. So that's rather shocking, isn't it? You were just explaining all of these fantastic benefits, and then they've looked at this enormous set of studies and they said, well, it doesn't work. And, you know, we actually checked just before this and, you know, many governments, including the UK and the US, are actively encouraging their citizens to increase their omega-3 intake from oily fish.

So does that suggest that the latest science is really at odds with this advice? And does it mean that we should all stop encouraging our children to eat that salmon on your plate? No, absolutely not. Because we also have many trials that show a very clear benefit of omega-3. So for example, there's the REDUCE-IT trial, which was in 8,000 people, where participants were given a purified version of a really high dose of EPA omega-3, or they were given a placebo capsule. And what we found was those who received the EPA omega-3 had much lower heart attacks, they had less strokes, they had less need for a procedure to open clogged arteries, and they even had much less death

compared to the people taking the placebo. So Sarah, I think most people listening to this will be really surprised there can be this level of disagreement on something that isn't brand new, but actually there have been massive studies. So how can you have like one trial showing a really big impact? And then this other thing where you said there's this big, what they call sort of meta-analysis, you said, so looking at all these trials saying that there's no impact, like how can that be? And is that very unusual in nutritional science? No, not at all.

And Jonathan, I actually think that all the best nutritional scientists have a lot of healthy disagreements. So firstly, unlike in the JISI trial, which showed a benefit of omega-3, in recent studies, most of the participants were already taking statins. And so if they're already taking all of these drugs that are preventing the outcomes that we're looking at, so these cardiovascular outcomes, is it surely no surprise that we don't see any added benefit from adding omega-3 into the diet? We also need to think about the dose and the type of omega-3. So for example, in the REDUCE-IT trial that I just

talked about that showed a benefit, despite actually in that study, they having a high statin use, the dose of EPA that they gave was exceptionally high. So way beyond what you would get naturally with oil-efficient intake. And also the baseline characteristics of the participants really seems to matter. So what we know is for people that have quite a high triglycerides in their blood, the evidence I think is fairly consistent that EPA and DHA omega-3 are beneficial. And I also think for people that have a low EPA and DHA omega-3 intake or low fish oil intake, the evidence I think is fairly consistent that there is a benefit in those individuals. So again, it's taking us back to

thinking about exactly what we're giving them, how much we're giving them, who the individual is, and what they're already eating. So I think you're presenting quite a complex picture where you're saying there's certain people for whom this is beneficial. You said particularly people with high triglycerides, which is sort of really like all the total level of fats in your blood. Is that the right way to think about it simply, Sarah? Yeah. So we know that EPA and DHA taken by people with high triglycerides has a really good triglyceride lowering effect. And it can be in the region of around 30 to up to 45%. And this is shown from quite robust randomized clinical trials. And I was going to say that, you know, the one thing I do know about this is that we actually measure this level of triglycerides, right, this level of blood fat after a meal as part of the standard test that everybody does who does. So we've done this for,

you know, more than 50,000 people. And I think what was, you know, sort of a surprise at the beginning of this is this huge variation in those levels in people who are, you know, healthy, not people who have cardiovascular disease. So there are lots of people with very low levels of triglyceride, right, Sarah? And there are also some people, we see roughly, I would say about a third, I think, where those levels after meals are really quite high and enough to really change sort of the advice. So is that the same way of thinking about this? So it's going to be quite personalized. There'll be people, therefore, for whom this doesn't really make a difference, but there will be quite a significant, but a minority of people with these high triglycerides levels where those are the

people where you believe this omega-3 could make a difference. Is that? Yeah, absolutely. And Jonathan, I think there's also the situation where people may have low fasting triglycerides, but they have a very high post-meal triglyceride response. And our research that we've conducted at King's quite clearly shows that if you add fish oil or EPA and DHA omega-3 to your diet, you can reduce, even with people that have normal fasting triglycerides, this post-meal triglyceride response. Are there any other benefits from these omega-3s? Yeah, so I think there's really good evidence from all sorts of kinds of trials that adding

EPA and DHA, omega-3 and fish oil into the diet reduces blood pressure. It improves blood vessel function. But really importantly, it has a very potent anti-inflammatory role. And we actually know most chronic diseases now that are impacting Western populations, such as type 2 diabetes, some cancers and cardiovascular disease, is underpinned by chronic inflammation. And this is where I think EPA and DHA are particularly valuable. So Sarah, there's a lot of evidence to support omega-3 and there's a lot of evidence against it. Can you settle this once and for all? Is there something fishy going on here?

No. That was a terrible joke, but you know, I managed to get it in. I've thrown you off completely. Oh my gosh. So Jonathan, there is nothing fishy going on here in my opinion. I think that the evidence is really robust showing that EPA and DHA omega-3 and fish oil have favourable impacts on lots of mechanisms that underpin chronic diseases. I think it's really clear, like I said, that they have anti-inflammatory roles, that they have roles in reducing triglycerides. I think that if we want to think of the long-term benefits, I think it's quite clear that for people who don't consume adequate amounts of oily fish

or supplemental EPA and DHA, omega-3, that there will be a benefit from including them in their diet. And I also believe that there is an added benefit for people that do have high fasting triglycerides as well. So Sarah, you've talked a lot about the potential benefits here. Now, I know that Tim would be quite sceptical, actually, if he was sitting here. And I think there's a couple of reasons, as I understand it. One is, I think, a very big environmental argument about the massive overfishing and I think a very big environmental argument about the, you know, the massive overfishing. And I think his concerns that sort of the farm fish are much less healthy than people think. And then I think he'd have a different argument, which is to say a lot of these studies are on people who are eating really quite unhealthy diets. And actually, if they just shifted to a really gut healthy, you know, primarily plant based diet, you'd get the same benefits and you wouldn't be worrying about, you know, can I eat these fish? How much of that argument would you be willing to accept?

So can we start with farmed fish versus non-farmed fish, which is something people often ask about. So interestingly, farmed fish actually has more omega-3 than fresh fish. Now this is because farmed fish are fatter, so they just have a lot more oil in. So it does mean that they also have a lot more omega-6 and there is some questions as to regarding whether they have as much of the other healthy components. Some of the nutrients that you mentioned earlier, so we touched on the fact they're high in vitamin D, high in iodine and selenium. So I think I would say though the jury's kind of out there on that. I think it's really important to recognise that fresh fish can be very expensive and I think that if we're

encouraging people, which I would, to consume oily fish in their diet if it's acceptable to them, that actually some very cheap alternatives like frozen salmon do often come from farmed sources and I believe it's better to have frozen farmed salmon than no salmon in the diet, in my opinion. Now, surely it's better that actually people just have generally an overall healthy diet. And if they have an overall healthy diet, that will negate potentially any downside of not having omega-3 or fish oil in their diet. And I think to use vegans and vegetarians is a fantastic example for this. So there's something called the omega-3 index, which is basically a way that we can measure

in someone's blood what their intake of omega-3 is. And this is really great for us as nutritionists, because what's the hardest thing for us to do, as you know, Jonathan, is to actually accurately say what people are eating. It's blooming difficult to do that. But what is fabulous about omega-3 is the only way we can have it in our blood is if we've eaten it. And omega-3 incorporates into our red blood cell membranes. So what's fantastic is we can take a blood sample from someone, we can measure the levels of EPA and DHA in their red blood cell membranes, and we can say exactly what their intake is. And then from that, we can say what your omega-3 index is. And what we know is that

the omega-3 index, which is basically saying how high or low your omega-3 intake is over a long period of time, is very low in vegans, is intermediate in vegetarians because they may consume some eggs, for example, and is quite high in many omnivores. Now, what we do know is that despite that, vegetarians and vegans do have lower risk of cardiovascular disease compared to omnivores, people that consume meat or people that consume animal products. Now, is that because actually omega-3 doesn't have any effect? It's all a load of nonsense? I don't believe so. I believe it's because, just like Tim says, so I will agree with him a little bit on this, that's very good evidence to show even though they don't get enough EPA and DHA or omega-3, that actually all the other aspects of their diet, the fact they have more fiber, the fact that they're not having high saturated fat, you know, lower salt intake, etc. All of these other benefits, I think, outweigh the fact that therefore they're not getting omega-3 in their diet. Now, what we don't know, and what I'd love to be able to answer is, what if we took those vegans and vegetarians and gave them an omega-3

supplement, would we see an even greater improvement in their reduction of risk? I think we probably would. And that would be really interesting. And it's something we could actually now do because you can now get vegetarian or vegan sources of omega-3 of these EPA and DHA from algal sources. Because that's actually where EPA and DHA come from. They come from algae and the fish eat the algae and that's why they get incorporated into fishy fat. Got it. So we could cut the fish out as the middlemen and just go straight to the sea plants.

Yes, but it's expensive and that's the problem. There is a lot of agricultural developments going on developing GM plants that contain EPA and DHA. So I think things will change quite soon. But that would be a great study. Perhaps we can do that, Jonathan, Zoe. That sounds fascinating. Well, Sarah, thank you so much. And I know we packed in an awful lot into this episode. So Sarah, you've done an amazing job. And I also love that we're showing the challenges of giving nutritional advice. And obviously, if even art artists aren't agreeing, then it tells you that in a sense,

this is not yet clear cut. I think what we can promise, right, Sarah, is that as the science progresses, we'll come back and share that information with you here. And of course, continue to update everything that sits within the Zoe advice. Absolutely, Jonathan. And once Tim realizes he's wrong and I'm right, he can come back and give the update. I look forward to that very much. Thank you. And if you'd like to try Zoe's personalised nutrition programme to improve

your health and manage your weight, you can get 10% off by going to joinzoe.com slash podcast. I'm Jonathan Wolfe. And I'm Sarah Berry. Join us next week for another Zoe podcast.