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Should Everyone Supplement with Fish Oil?


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Fish oil may not be all it was cracked up to be, especially in the case of heart disease prevention. In this podcast I'll discuss what the latest research says about fish oil supplementation.

Revolution Health Radio podcast, Chris Kresser

Maybe two or three years ago most patients that came to me were taking some kind of fish oil supplement because the idea was we weren’t getting enough omega-3 in our diets, and there were studies that suggested that fish oil goes a long way toward preventing heart disease. But there have been some chinks in the armor this hypothesis over the past few years and especially so over the past year.

In this episode, we cover:

0:24  My two upcoming London seminars
6:43  The latest research on fish oil supplementation
10:47 Testing for omega-6 and omega-3

Links We Discuss

Chris Kresser: Hey, everybody, it’s Chris Kresser from Revolution Health Radio.

My Two Upcoming London Seminars

Today I’m going to answer a listener question, but before I do that, I want to remind you that my two events in London, October 31 and November 1, are coming up, probably only a few days away by the time you hear this.

The Saturday event is geared toward the general public and will cover a broad range of topics in the ancestral nutrition and health and functional medicine world. I like to do those events in a way that’s driven by the interests of people in the room. That one is nearly sold out, I believe, but I think there are still a few spaces. It’s going to be at King’s College, and a paleo lunch will be provided. It’s from 10 a.m. to 4 p.m.

And then the Sunday event is geared more toward clinicians and healthcare practitioners, though all are welcome to attend. I’m going to focus here more on trends that will define the future of medicine, functional medicine, and the crucial role of the exposome in health and disease. I’m going to present a systems model of functional medicine that I’ve developed to guide my own practice and also for my clinician training program. I’m going to talk about how to structure and layer a treatment for maximum efficacy, how to customize nutrition plans for individual needs, and of course, we’ll have a Q&A as well. That’s also from 10 a.m. to 4 p.m., will also include lunch, and is also at King’s College. There are still a few spaces left in that one as well, and this is going to be my first trip to the UK and probably my last trip, at least for a long while. I don’t have any plans to come back in the near future, so if you’re interested, I would love to meet you and see you at the events.

For the public event, you can find more information and register at ChrisKresser.com/UKpublic, and for the practitioner/clinician event, you can go to ChrisKresser.com/UKclinician.

OK, so now let’s dive into the show today. We have a question from Daniel from Sweden, so let’s give it a listen.

Question from Daniel: Hello, Chris. Daniel here from Sweden. In a local paleo forum, we have been discussing supplementation with omega-3 and if it’s needed or not, and there are quite a few people pushing a product from Zinzino, which is called Balance Oil or something like that. They have a test where they test out the ratio between omega-6 and omega-3, and I just wanted to hear your thoughts on it because it seems like their test almost always shows that the ratio is bad, which is in conflict with my own thoughts. I mean, if you eat a varied paleo diet and avoid excessive amounts of nuts and so on and you eat a lot of fatty fish, I think you should be able to have a good ratio without supplementing. It would be great to hear your thoughts on this and maybe get a better understanding if these tests are legit or if you think it’s just bad, bad testing. Thank you. Bye.

Chris Kresser: OK, so, yeah, this is a really good question, and I think a lot has changed in this area over the last even maybe three or four years, but certainly over the past 10 years. I think maybe 10 years ago, the vast majority of people would say, yes, everyone should be taking a fish oil supplement, and in fact, most patients that come to me, maybe not quite so much now, but maybe two or three years ago almost everyone that came to me was taking some kind of fish oil supplement because the idea was we weren’t getting enough omega-3 in our diets, and there were studies that suggested that fish oil goes a long way toward preventing heart disease, so this led to people taking sometimes quite high doses of fish oil capsules, maybe 3 to 5 grams a day or even more, and it became a really large industry and business with a lot of money at stake. But there have been some chinks in the armor this hypothesis over the past few years and especially so over the past year.

I actually recently published an article on this subject called “Should You Really Be Taking Fish Oil?” That was back in June. If you haven’t read that, I would definitely recommend googling it and reading it because I summarize a lot of the more recent evidence that suggests that fish oil may not be all it was cracked up to be, especially in the case of heart disease prevention.

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The Latest Research on Fish Oil Supplementation

Initial studies suggested that fish oil was beneficial for heart disease, particularly over the short term, and for people who had already had a heart attack—so this is secondary prevention, people with pre-existing heart disease—but several studies since then, including large studies and reviews of randomized clinical trials, have found that in adults even with pre-existing heart disease, long-term supplementation over three years with fish oil had no significant impact on cardiovascular endpoints. There were a few other trials that have looked at the effect of short-term fish oil supplementation on atrial fibrillation, and none of those trials—there were three of them—found that fish oil improved patient outcomes.

And then the meta-analysis of randomized clinical trials focusing on cardiovascular endpoints, like heart attack and stroke, found that fish oil did not reduce cardiovascular events or death and concluded that the evidence doesn’t support using fish oil supplements for secondary prevention of heart disease, meaning, again, people who have already had a heart attack. There is not much evidence to support that taking fish oil in that population will really do much of anything. And lest you think it was a problem with that meta-analysis, there were two other meta-analyses that were published right around the same time that came to similar conclusions.

Now, this isn’t to say that there isn’t any research that supports the use of fish oil for cardiovascular health. There was one meta-analysis in 2013 that found a protective effect on fish oil for preventing sudden death and heart attack, and certainly you can find studies that have had positive results, but I would say overall when you look at some very large recent studies and meta-analyses, the evidence supporting fish oil for preventing cardiovascular events is pretty weak.

What about metabolic syndrome? Because it’s obviously possible that fish oil could not be helpful for cardiovascular disease but could be helpful for metabolic problems. It’s another reason that it’s typically prescribed. If somebody, for example, has high triglycerides and low HDL, they might be given a higher dose of fish oil to deal with that. There is a recently published randomized clinical trial that looked at adults with metabolic syndrome, and they found that supplementation of 3 grams a day of fish oil along with 10 mL per day of olive oil for 90 days improved a lot of blood markers that are associated with metabolic syndrome. But it was interesting to note in that study that the fish-oil-plus-olive-oil group had better results than the group that took either fish oil alone or olive oil alone, and one reason for that may be that olive oil is rich in antioxidants and may have protected against the potentially greater risk of oxidative damage that comes from consuming a lot more polyunsaturated fat, which is what’s in the fish oil. So we might be seeing a scenario here where a higher dose of fish oil has some benefits, but because it’s polyunsaturated fat and has the potential to oxidize, there is also harm, and so we see no net change or in some cases even adverse effects when someone takes a high dose of fish oil, but when you add the olive oil, it has antioxidants and kind of cancels out some of that potentially harmful effect that the higher doses of fish oil have.

Testing for Omega-6 and Omega-3

But let’s bring this back a little bit more to Daniel’s question because he specifically asked about the ratio between omega-6 and omega-3 and some of the tests that are available to determine that ratio. I’ve seen a similar thing, too. I do a really advanced blood panel for patients that has, among other things, the omega-3 index as part of it, so it looks at the ratio of omega-6 fats and omega-3 in the blood, and it creates a scores. And I’m trying to remember if I’ve ever seen anyone that has had a normal score in the green. They rate the score in a kind of like traffic signal fashion with green being normal, yellow being intermediate or caution, and then red being really bad. Almost all of the values that I’ve seen have been in the yellow category, and this is probably a consequence of the fact that there’s so much omega-6 in our diet that it’s really, really difficult to get back to that historical ratio of omega-6 to omega-3, which was about 1:1 in some populations, maybe 2:1 in other populations. But in Western populations these days, the average is probably more like 9:1 or 10:1, and in some cases, on the Standard American Diet, if someone’s eating just tons of processed food with soybean oil—which can comprise up to 9 percent of total calories for some people—the ratio can be as high as 30:1.

Earlier on—and anyone who’s been following my work for a while will know this—I used to put a lot of emphasis on the omega-6-to-omega-3 ratio and it’s importance, but over the past couple of years, I’m changed my mind about that and gradually revised my views, and I’ve been writing about that and speaking about it, so this probably won’t be news to you, but it seems now that there’s less evidence really supporting the importance of the ratio and more evidence just supporting the overall intake of omega-3.

For example, if your intake of omega-3 is really low or nonexistent, you’re going to have problems. Of course, your ratio will be high because you’re almost certainly getting omega-6 from the diet. It’s much harder to avoid than omega-3 is. But if your intake of omega-6 is higher, especially if it comes from real, unprocessed food—which I’ll come back to in a second—let’s say you’re eating avocados and chicken skin and nuts and natural foods that are high in omega-6, but you’re also eating some preformed EPA and DHA from cold-water fatty fish and some other omega-3’s, plant-based omega-3’s from vegetables, walnuts and flaxseeds, etc., from my reading of the research and a lot of discussion with Chris Masterjohn, whose opinion I really respect on this issue—he’s done a ton of research on the polyunsaturated fats—and in my reading of the literature, there’s not a lot of evidence supporting the idea that that person who’s eating real-food-based omega-6 even in substantial amounts and omega-3’s is going to be at increased risk of disease. The omega-3 index was created with this whole ratio in mind, so even someone like that, who’s eating healthy omega-6’s and a fairly substantial amount of omega-3’s, will still probably score in the yellow category on that test, but I don’t really think that you can say that that person is going to be at significantly increased risk of disease.

Now, let’s consider another scenario where someone is eating, again, a Standard American Diet. They’re eating a lot of chips and fried foods, foods that have been fried in omega-6 polyunsaturated seed oils like corn oil, cottonseed oil or soybean oil, sunflower or safflower oil, and they’re eating out in restaurants all the time—unfortunately, restaurants tend to use those oils because they’re so cheap—and then their intake of omega-3 is really low, and they come back with a score of yellow on that test. That person’s going to be in a different position than the person who has a high or even medium-high intake of omega-6 from, like, avocados and nuts and chicken, and also has a pretty substantial intake of omega-3, but the ratio is still putting them in the yellow versus somebody who has a low intake of omega-3 and a pretty high intake of omega-6, all from processed and refined foods. Those people both would show up as yellow on that omega-3 index test, but they’re clearly not going to have the same risk, at least in my opinion, because it matters a lot where these fatty acids are coming from in the diet.

So I think that the ratio should be taken with a grain of salt, and there’s no reason, in my mind—I’m not convinced that it’s necessary to avoid or restrict omega-6 as it occurs in foods like avocados and nuts and seeds and chicken skin, all of which have a lot of health benefits. What’s interesting is that so many studies show that consumption of tree nuts is inversely associated with heart disease, and those are some of the richest sources of omega-6 fats, so I don’t see a need to restrict omega-6 from those foods, but it is important to get enough omega-3, and the recent studies suggest that fish oil is not the way to do that. They suggest that eating cold-water fatty fish and shellfish is consistently still in studies associated with improved outcomes, both cardiovascular and metabolic, and also improvements in overall health, cognitive function, etc., and they’re pretty significant differences, and that may be because fish does not just contain fish oil; it contains a lot of other beneficial nutrients that are important for humans. And then finally, you would want to reduce your intake of industrially processed vegetable and seed oils because they would tend to be oxidized because they’re heated at high temperatures and they don’t provide a lot of nutritional value.

So there are kind of three things there, and I think if you just get a good amount of omega-3 from food, don’t worry about your omega-6 from nutrient-dense real foods, and limit your omega-6 from industrially processed sources, you’ll be in good shape. It all kind of falls into the category of “eat real food!” I think over the past several years we’ve gotten a little too obsessive about some of this stuff. I never personally saw anyone improve symptomatically by minimizing their intake of omega-6 from real foods, and I don’t think that the research is there to support it.

I hope this answers your question, Daniel. As you said, if you eat a varied paleo diet and avoid excessive amounts of nuts—I don’t think the reason, necessarily, to avoid them is because of the omega-6, but if you’re trying to watch your weight, that might be a reason to moderate your intake—but you should be fine even if your ratio is in the yellow range.

All right, so that’s it for today. Again, if you’re interested in seeing me speak in the UK, you can go to ChrisKresser.com/UKpublic for the public event or ChrisKresser.com/UKclinician for the healthcare practitioner/clinician event. That’s it for today. I’ll see you next time.

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Join the conversation

  1. I just came across this article, so I’m joining in late, but I appreciated your thoughts. I also liked a lot of the comments. I just want the standard American diet to keep moving toward more fresh food and not worry so much about supplements…or even what hunters and gatherers ate back in the day.

  2. I’ve just listened to this podcast and I’m pleased to find you’ve reached similar conclusions as myself. What are your thoughts on vitamin D supplementation for those of us in less sunny climates like the UK where it’s difficult to get natural sunshine for most of the year?