- The benefits of fish oil supplementation have been grossly overstated
- Most of the studies showing fish oil benefits are short-term, lasting less than one year
- The only fish oil study lasting more than four years showed an increase in heart disease and sudden death
- Fish oil is highly unstable and vulnerable to oxidative damage
- There’s no evidence that healthy people benefit from fish oil supplementation
- Taking several grams of fish oil per day may be hazardous to your health
A new study was recently published showing that 3g/d of fish oil in patients with metabolic syndrome increased LDL levels and insulin resistance.
Unfortunately, I don’t read Portuguese so I can’t review the full-text. But this study isn’t alone in highlighting the potential risks of high-dose fish oil supplementation. Chris Masterjohn’s latest article on essential fatty acids, Precious yet Perilous, makes a compelling argument that fish oil supplementation – especially over the long-term – is not only not beneficial, but may be harmful.
This may come as a surprise to you, with all of the current media hoopla about the benefits of fish oil supplementation. Yet the vast majority of the studies done that have shown a benefit have been short-term, lasting less than one year. The only trial lasting more than four years, the DART 2 trial, showed that fish oil capsules actually increase the risk of heart disease and sudden death.
A 2004 Cochrane meta-analysis of trials lasting longer than six months suggests that the cardiovascular benefits of fish oil have been dramatically over-stated. They analyzed 79 trials overall, and pooled data from 48 trials that met their criteria. The only effect that could be distinguished from chance was a reduced risk of heart failure. Fish oil provided no reduction in total or cardiovascular mortality.
Too much fish oil can wreak havoc in your body
Omega-3 fatty acids are highly vulnerable to oxidative damage. When fat particles oxidize, they break down into smaller compounds, like malondialdehyde (MDA), that are dangerous because they damage proteins, DNA, and other important cellular structures.
A study by Mata et al demonstrated that oxidative damage increases as intake of omega-3 fat increases. The results of this study were summarized in the Perfect Health Diet, by Paul and Shou-Ching Jaminet:
Notice the clear increase in TBARS (a measure of oxidative damage of the LDL particle) with omega-3 fat. It’s important to note that this was only a 5-week trial. If it had gone on for longer than that, it’s likely the oxidative damage caused by omega-3 fats would have been even worse. This isn’t surprising if you understand the chemical composition of fats. Polyunsaturated fats (PUFA) are highly vulnerable to oxidative damage because they’re the only fatty acids that have two or more double bonds, and it’s the carbon that lies between the double bonds that is vulnerable to oxidation (as shown in the figure below):
Another thing worth noting, if you haven’t already, is that intake of saturated and monounsaturated fats does not increase oxidative damage by a significant amount. This is illustrated in both the table and the diagram above: saturated fats have no double bonds, which means they are well protected against oxidation. MUFA is slightly more vulnerable, since it does have one double bond, but not nearly as much as PUFA which has several double-bonds.
A randomized, double blind, placebo-controlled trial likewise showed that 6 grams per day of fish oil increased lipid peroxides and MDA in healthy men, regardless of whether they were supplemented with 900 IU of vitamin E. And consumption of fresh, non-oxidized DHA and EPA has been shown to increase markers of oxidative stress in rats.
Fish oil not as beneficial as commonly believed
To be fair, at least one review suggests that fish oil supplementation is beneficial in the short and even intermediate term. A recent meta-analysis of 11 trials lasting more than one year found that fish oil reduced the relative risk of cardiovascular death by 13 percent and the relative risk of death from any cause by 8 percent.
But the effect seen in this review was mostly due to the GISSI and DART-1 trials. They found that fish oil may prevent arrhythmia in patients with chronic heart failure and patients who have recently survived a heart attack.
However, there is no evidence that people other than those with arrhythmia and chronic heart failure benefit from taking fish oil or that doses higher than one gram of omega-3 fatty acids per day provide any benefit over smaller doses. And then there’s the rather disturbing result of the DART-2 trial, the only fish oil study lasting more than four years, showing an increase in heart disease and sudden death.
It’s logical to assume the effects of oxidative damage would take a while to manifest, and would increase as time goes on. That’s likely the reason we see some benefit in short- and intermediate-term studies (as n-3 displace n-6 in the tissues), but a declining and even opposite effect in the longer-term DART-2 trial (as increased total PUFA intake causes more oxidative damage).
The danger of reductionist thinking in nutritional research
The current fish oil craze highlights the danger of isolated nutrient studies, which unfortunately is the focus of nutritional research today. Kuipers et al. eloquently described the risks of this approach in a recent paper:
The fish oil fatty acids EPA and DHA (and their derivatives), vitamin D (1,25-dihydroxyvitamin D) and vitamin A (retinoic acid) are examples of nutrients that act in concert, while each of these has multiple actions(7,8).
Consequently, the criteria for establishing optimum nutrient intakes via randomised controlled trials (RCT) with single nutrients at a given dose and with a single end point have serious limitations. They are usually based upon poorly researched dose–response relationships, and typically ignore many possible nutrient interactions and metabolic interrelationships.
For instance, the adequate intake of linoleic acid (LA) to prevent LA deficiency depends on the concurrent intakes of α-linolenic acid (ALA), γ-LA and arachidonic acid (AA). Consequently, the nutritional balance on which our genome evolved is virtually impossible to determine using the reigning paradigm of ‘evidence-based medicine’ with RCT.
Interest in fish oil supplementation started with observations that the Inuit had almost no heart disease. It was assumed their high intake of marine oils produced this benefit. While this may be true, at least in part, what was overlooked is that the Inuit don’t consume marine oils in isolation. They eat them as part of a whole-food diet that also includes other nutrients which may help prevent the oxidative damage that otherwise occurs with such a high intake of fragile, n-3 PUFA.
It’s also important to note that there are many other traditional peoples, such as the Masai, the Tokelau, and the Kitavans, that are virtually free of heart disease but do not consume high amounts of marine oils. What these diets all share in common is not a large intake of omega-3 fats, but instead a complete absence of modern, refined foods.
Eat fish, not fish oil – cod liver oil excepted
That is why the best approach is to dramatically reduce intake of omega-6 fat, found in industrial seed oils and processed and refined foods, and then eat a nutrient-dense, whole-foods based diet that includes fatty fish, shellfish and organ meats. This mimics our ancestral diet and is the safest and most sane approach to meeting our omega-3 needs – which as Chris Masterjohn points out, are much lower than commonly assumed.
Some may ask why I continue to recommend fermented cod liver oil (FCLO), in light of everything I’ve shared in this article. There are a few reasons. First, I view FCLO as primarily a source of fat-soluble vitamins (A, D, K2 and E) – not EPA and DHA. Second, in the context of a nutrient-dense diet that excludes industrial seed oils and refined sugar, and is adequate in vitamin B6, biotin, calcium, magnesium and arachidonic acid, the risk of oxidative damage that may occur with 1g/d of cod liver oils is outweighed by the benefits of the fat-soluble vitamins.
So I still recommend eating fatty fish a couple times per week, and taking cod liver oil daily, presuming your diet is as I described above. What I don’t endorse is taking several grams per day of fish oil, especially for an extended period of time. Unfortunately this advice is becoming more and more common in the nutrition world.
More is not always better, despite our tendency to believe it is.
Note: As always, I’m open to discussion and dissenting views. But please don’t link to short-term studies on the efficacy of fish oil, because as I’ve explained in this article, it’s the long-term effects that we’re primarily concerned with. I’d be interested in seeing any studies longer than 2 years showing that 1) fish oil benefits extend beyond reducing arrhythmia in patients with chronic heart failure and patients who have recently survived a heart attack, 2) doses higher than 1g/d produce a larger benefit than doses of 1g/d, and (most importantly) 3) doses of >1g/d or higher do not increase the risk of heart disease or death
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Tags: damage, dha, epa, fish, mortality, oil, oxidation, oxidative
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I think I can stand behind suggesting eating fish over taking fish oil, but in the event that you’re not gonna have fish that day, would a 3-gram dose of fish oil be a gross overestimation of the fish oil content you’d consume from eating a serving of whole fish? Without being overanalytical that kind of seems like not that much fish oil. I’d be more worried about the 10-20g/day dosers.
Unfortunately these are metas which means that the original methodology cannot be critiqued. If most of these folks were taking rancid fish oil, I would almost expect these results. Almost all fish oil in capsules is (potentially) rancid off the shelf.
Does this mean the 2g of jarrow / vital choice fish oil recommendations should be stopped, or reduced?
Perhaps the plant based, omega-3 ALA from flax seeds, etc might be a better option. Less chances it oxidizes than fish oil (EPA/DHA), and if nothing else, ALA promotes glutathione
Good article, Chris. Bill, that’s not true — read the Cochrane Review, for example, and you will see that they spend an extraordinary amount of time critiquing the methodologies of the original studies and in fact a large portion of their statistical analysis was aimed at taking into account methodological differences between studies.
Chris, A big thank you for this article. I have been seeing hints of this elsewhere and now the details. I have been concerned about fish oil supplementation for one simple fact — most of the brands contain soy oil. I know that soy is poison and I am trying to reduce my intake of soy and since it seems to be in ALL refined foods, it is hard. It seems ridiculous to take something that is supposed to be good for you and then back load it with an extremely harmful oil even if it is a binder. I have also seen Vitamin D supplements with soy in them. Very disturbing.
You are so right, too much PUFA is bad and an omega 6/3 ratio that is or too high or too low is bad. Furthermore do fish oil supplement provide too much EPA in relation to DHA. Just limit your omega 6 intake and eat fish a couple of times per week.
Does this include krill oil? I’ve been eating fish 3 times a week and taking 2 krill oil capsules.
Another great post on the possible dangers of gulping down high doses of fish oil supps. I recently had a brief post about this here : http://abundantbrain.com/2010/10/omega3/ and linked to your stuff regarding animal vs. plant sources of EPA/DHA and the fish oil buyer’s guide. I have long been skeptical of the studies of isolated nutrients not part of a mixed whole foods diet- especially for essential fatty acids which must go through several biochemical conversions and will be affected by the digestive/metabolic environment. The Kuipers, et al. paper makes some excellent points.
What does concern me though is the realistic fact that nearly everyone in the U.S. and many other places gets too much omega-6 EVEN those who are cognizant and try to limit the dose. It’s just so ubiquitous. I’m curious as to your recommendations for adequate dietary omega-3 for those who do not eat seafood due to allergies or other reasons.
Thank you. What would you recommend as the best way to maintain a healthy level of vitamin D in the body? (I live in New Hampshire, sun is scarce many months of the year.) I may have missed this somewhere in other posts.
Is it possible that the fish oil used could taint the results? Considering that there appears to be a lot of pretty bad supplements out there, containing PCBs, it makes me wonder if the actual brand used has an effect on the results. I have been to taking Omegabrite for a while now. Sure hope it hasn’t been doing more harm than good…
If 1 tsp (about 4.5g) has ~ 500mg DHA +/- and ~ 300mg DPA +/- and fatty fish can have about 4-5g (total) per 200g/7oz serving, then 1 tsp of cod liver oil daily and 2 servings of fatty fish (assuming 200g per serving, which isn’t a lot) provides on average 2g+ total EPA/DHA. To your point, many healthy, and long-lived peoples do not consume a lot of marine-based n-3. I’ve been taking too much no doubt, and so as not to drive myself crazy with calculations etc. If I get about 1-2g per day, I’m doing well I figure (given I’ve cut out the n-6 sources etc)
i think fish oil can effectively ameliorate an omega 3 deficiency which a lot of people get into thanks to our high veg oil diets otherwise known as SAD. but if you correct a deficiency and start eating right at the same time, ie, limiting veg oils, eating more meat less carb and so on then i think that is when fish oil becomes counter productive.
this would explain short term results seen in abbreviated studies right?
Chris: liver is a no go! gag, but I loves me eggs. I’m good on the other nutrients too. It’s also important for folks to remember that too much n-3 is bad too as those fats compete with the same enzymes as n-6, just as an excess of n-6 can inhibit n-3 elongation, excessive n-3 (especially EPA I’ve read) can interfer with AA elongation…that step is there for a reason ya? All goes back to balance.
I think that fish oil consumption is not about eating fish oil, it is about bringing your omega6/omega3 ratio to optimum level.
My review of this fish oil trials is the dosage used is laughable low. So low that it could not have a positive effect on the omega6/omega3 ratio. That is why you are not seeing positive results in those trials. Also a friend who works in these type of trials says they use the absolute cheapest nutrients to test so the patients are getting crap-that also screws up the results.
I test that ratio at least every 6 months and the only way I can bring my ratio close to 2 is 4.8 grams of fish oil plus being an absolute Nazi about avoiding omega 6 fats including not eating any nuts other than macadamia nuts. By doing so I brought my ratio of omega 6 to omega 3 down to 2.7. Because I live in a rural area where good fish is not available, fish oil is my only choice.
Also William Davis, the famed preventative cardiologist, has been treating thousands of very difficult heart patients with high doses of fish oil (and other things) for over 10 years. All the cardiologists in his region refer their hopeless cases to him.
In that time he has had no cardiac events in the thousands of patients he has treated for a decade. That means: no stents, no bypass surgeries, no heart attacks and no strokes. He had one person die because he lost 5 close relatives in one year. In addition he is seeing arterial plague progression halted or reversed in most of his patients.
What is needed is to move the oxLDL test out of the lab and into the hands of the public so this issue can be settled for each person. In the meantime, I have climbed aboard the optimum omega6/omega3 train and I am riding until that test is available. Although I am doing the absolute certainty test by getting a heart scan in the spring.
Thanks so much for this article. I had suspected this and wince when I hear about young healthy people taking back 15 capsules a day.
Anecdotally, I switched to Green Pastures FCLO and I have to say it’s had much more of an impact on my health, no idea what’s making the difference as I always thought my diet was nutrient-rich.
On that point, at this latitude (Ireland), do you really think the 400IU of D in the FCLO is sufficient? I do supplement with an extra 2,000IU D3, and I notice it makes me feel better and increases my resistance to colds. Am I harming my health in the long run doing this?
I have been using seal oil for about 3 years because of chest pain
and it has helped. IMO much better than
fish oil and the oxidation factor. Read this
I’m on the side of limiting fish oil consumption and upping ones fish consumption. I think high levels of omega-3 are probably beneficial if you live in sub-zero conditions, but otherwise I believe the benefits of fish come from taurine & to a lesser extent magnesium.
I’m also curious about what those who can’t eat fish should do. My son has a potential fish allergy is is currently taking a soy free algae based DHA supplement. I also worry about my other sons eating a lot of fish due to contamination issues (plus they just don’t like it anyway). Suggestions?
Given your continued recommendation for Green Pastures FCLO, do you have any thoughts on dosage for children? Are 2 yr old has been taking 1/2 a teaspoon every since he could eat solid foods.
Second question, does a person who currently takes high dosage of fish oil to relieve the symptoms of Rheumatoid arthritis have an alternative?
Thanks in advance for any thoughts you may have on this.
Thanks for the quick reply!
My omega-6 intake could probably be reduced significantly, which is in the works as we speak. When talking about dosage for people like myself with RA, should I be taking FCLO or straight fish oil? FCLO does not disclose the EPA/DHA levels.
Great article, you mention eggs, if you have no access to pastured eggs, or even if you do, then fish eggs are a great choice, fish roe is a cheap source & I eat it once a week with the occasional kina ( sea urchin eggs ) . I think that fish eggs provide you with iodine.
Obviously if they’re oxidized to oblivion they’re no good. I can’t help but think that the mixed results of fish oil supplementation have to do with the poorly abosrobed ethyl ester form. I just can’t see a bit of oxidation being worse than not being able to turn off eicosanoids properly. In either of those cases the data wouldn’t be a true reflection of better quality fish oil.
And of course nobody is going to debate that some wild salmon is preferable to any fish oil. There is also the wonderful and very paleo option of BRAINS.
It is worth noting that the DART 2 researchers disagree with your interpretation of the results. From the paper: “An adverse effect of fish oil as distinct from dietary fish is unlikely.” There is a good discussion in the paper of some reasonable explanations for their results. They seem to think that the result may not be statistically significant but also bring up the possibility that the fish oil group may have engaged in riskier behavior or skipped their usual medications due to the belief that the fish oil pills were adequate. The study was an RCT designed to evaluate the efficacy of dietary advice, not of fish oil supplements, and thus should not be taken as evidence against fish oil supplementation.
What are your thoughts about CLO that isn’t fermented? My plan was to finish the full bottle I have (Healthspan) and then buy Green Pastures. Am I getting any benefit from the Healthspan CLO or could it be doing more harm than good? BTW, I’m eating a healthy diet with no processed foods, no seed oils etc.
consumer labs is an independent lab that analyzes various OTC supplements for contaminates, listed ingredients, etc. Their more recent review of fish oil did not show any problems with rancid oils in the products they tested (with the exception of one fish oil product for dogs). Theoretically, there is a risk of rancid oils when taking fish oils, but it doesn’t seem to be as big of a problem as one might think. i agree we really need more long term studies with fish oil to give it a thumb’s up.
Great write-up, as usual; that first study you listed can be viewed in english via Google translate.
As per my comments via Matt’s blog, the LDL increase is a positive result of fish oil intake: the shift from VLDL to LDL. This is in addition to the beneficial effect of lowered trigs:
“Since the increase in LDL and consequently in total cholesterol levels appear to be due to the increase in the conversion of VLDL and LDL in the negative regulation of LDL receptor observed by other researchers. The increase in the concentration of LDL appears to be due to increase in size, which would be very favorable for the increase in the size of the molecule makes it less atherogenic (28,29).”
“Our data showed increased oxidative stress observed by increased levels of MDA in 45 days of treatment, but there was no change in levels of hydroperoxides assessed by CLT. It was found that the QL is a more sensitive and specific than the TBARS and suffers less interference in the assessment of oxidative stress in patients with MS (35,36). Thus, it is concluded that ingestion of fish oil does not increase oxidative stress.”
There still a lot to explore about fish oil, especially from a lipid peroxidization standpoint; I’ve personally seen too many benefits over the years to throw it out—myself, extremely low Tgs, elevated LDL and HDL, improved body comp to <7%, recued DOMS and increased athletic recovery, all at 6-9g/day EPA/DHA over the last 3 years.
Had I had a massive amount of lipid peroxidatization going on, I would have suspected decreased health and performance.
Whole food will always trump singular supplements any day of the week, but in the case of marine food, the source is extremely questionable at best.
I love it-sacred nutrition cows keep falling! We were so convinced of the benefits of Omega-3 supplements. Remember everyone saying we shouldn’t be afraid of fat, as long as it’s the good kind (omega-3)? I wonder what’s next? Vitamin D (it’s pedestal seems a little too high at this point)?
I own and run a specialty fish oil company. So you’d think I’d be upset about your post. I’m not.
Lately, we’ve been telling our customers to cut back on n-6 fats. We try to educate them on how to do this. The ‘reduce n-6′ message is on our blog, our emails, brochures and product inserts. Frankly, it’s bad business – I should be pushing more n-3, not less n-6.
But it’s the right thing to do.
To my customers, I’m their fish oil source. In my customer’s minds, it often does not compute why I’m asking them to eat less corn and soy oils. Our reduce-the-6 campaign is backfiring a little bit because it is like a car company asking people to ride bikes more often.
Your readers are an elite bunch. They get it. But most regular people just want a pill to fix their problem – they don’t want to know what caused the problem. Some of my customers get it – and they love it! But for the others, we’re trying a slightly revised approach now: less n-6 = less n-3 pills = save money!
They key is reducing n-6. As for oxidation, yes, it’s a problem. It’s a problem before the pills are made. It’s a problem while the product is ‘on the shelf.’ It’s a problem after consumption. This is not new. Double bonds have always caused problems. You will be reading more about this in the next few years – I know of some good research under way.
I’m a nutritionist and my peers are not collectively ready to discuss this yet. Your post nudges us in that direction. But I hope people don’t skim your post’s title and conclude that fish oil is now to be avoided. The Paloe-elite can drastically reduce their n-3 pill consumption. But most Americans can’t. They’re drowning in n-6 and fructose.
For now, I’d advocate less than 1 or 2 grams of n-3 per day. It’s a risk-benefit thing. In the meantime, those taking > 5 or 6 grams n-3 per day for years should expect some oxidative damage.
But I need to consume 2 gram minimal a day of Fish oil because I eat 50 gram, sometimes more, almonds a day and 4 or 5 eggs. This alone is about 8 grams of omega 6 which I need to belance with 2 gram Fish oil. So in my case it wouldn’t be smart to supplement 1 gram I think?
Even if that means dropping or reducing quality whole food packed with very good nutrients? Sorry, I don’t agree with that .
I meant almonds and eggs as nutrient dense food, not the fish oil.
No wonder people get so confused and give up trying to take the path to good health without the aid of the drug companies. I’ve been working hard to get my Triglycerides down without drugs through low carb eating, but felt like fish oil would be a big help. Now I am confused!
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