Update: I now recommend Extra Virgin Cod Liver Oil from Rosita as my preferred cod liver oil product. For more information, read this article. You can purchase EVCLO here.
Article summary
- 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
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.
Like what you’re reading? Get my free newsletter, recipes, eBooks, product recommendations, and more!
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 dissenting views, but I’m not convinced by short-term studies on the efficacy of fish oil. 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.
Better supplementation. Fewer supplements.
Close the nutrient gap to feel and perform your best.
A daily stack of supplements designed to meet your most critical needs.
I have been taking roughly 4400 mg. of high quality fish oil plus 2000mg. of niacin-(not the no flush) for a year and recently had labs done. My HDL increased to 105, my LDL decreased to 105 and my triglycerides decreased to 52. In addition, my last carotid artery scan showed a reduction in velocities (which means less plaque). I attribute this to the combo of fish oil and niacin. I eat a very low carb diet and am type 2 diabetic with an a1c of 5.6. After reading this very thought provoking article, I am thoroughly confused.
I definitely need to educate myself on this issue.
Thank you for your astute article.
Yes, it’s possible. And you’re the 2nd person in a week to mention a connection between gluten and tinnitus. That’s something I wasn’t aware of – although frankly, it doesn’t surprise me.
Ok, here is something I have to share. I used to have auditory hallucinations before which I used to sometimes hear a sound like a higher pitched version of whining. I read about A1 dairy and schizophrenia some day, removed it from my diet and my auditory hallucinations vanished.
I think if I had removed gluten from my diet it might be helpful also, since I suppose gluten greatly increases the intestinal permeability and allows passage of much more A1 dairy peptides such as BCM-7.
Thanks. Your post will serve as a reminder for me to get vinegar and oil on the side when I order salads. I sometimes forget to do that. That’s probably the one area where I get too much omega-6’s.
On a possibly related note, I’ve had tinnitus for two years now, and I’ve taken high doses of high-quality fish oil for 15 years. It might be a coincidence, but after going on a strict gluten-free diet about a month ago, and recently cutting out fish oil (6 days ago), my tinnitus is only about 1/5th the level it used to be, and has been at that lower level for five days now. I’ve experienced this low level before, but never for more than 2 1/2 days in a row.
I took the fish oil to reduce inflammation, but maybe it backfired on me!
Tedd: bread isn’t high in omega-6 (but it does have other problems, such as gluten and the impact of refined flour on blood sugar), so it’s not the issue in this case. Foods high in omega-6 are packaged, processed and refined foods containing industrial seed oils like corn, soy, cottonseed, sunflower, safflower & canola. Chips, crackers, cookies, fried foods, etc. Also restaurants use these oils almost exclusively.
If someone continues to eat those foods, it’s difficult to say what the lesser of evils would be. The best of the worst choices would be to get them to eat fatty fish 3-4x/week. If not that, then in the short term 3-4g/d of fish oil would probably be beneficial… but as the studies I mentioned in this article suggest, that effect would diminish over time and even reverse.
Chris,
I agree with your article; it just makes sense. My problem is the rest of my family, who continue to eat bread, and sometimes pasta. Is the lesser of the evils to supplement with 3-4g high-quality fish oil to counteract the too-high intake of omega-6’s? Or would it be better to live with the higher omega-6 intake and limit the fish oil to 1g?
Those are all excellent food-based sources, and provided your intake of omega-6 is low and you’re eating a whole-foods, nutrient-dense diet (which it sounds like you are), I think you’re right where you need to be.
Hi Chris,
Love your site. I frequent regularly.
I was just thinking about all the sources I get omega-3 from, and started wondering if I am maybe getting too much.
I eat salmon about once a week and I have canned tuna once a week (the only brand I buy is Wild Planet. they do it very differently with very high omega-3 and low mercury and no oils and no water added)
I eat a significant amount of Organic Valley’s pasture butter, probably about 4 tablspoons per day, which claims naturally occuring omega-3.
I take Green Pastures Fermented Cod Liver Oil / Butter Oil blend daily.
I also eat at least 2-4 organic eggs from free roaming chickens and sometimes they claim omega-3 on the package depending on where I buy them from (not always though).
So that’s 3-4 significant sources of omega-3. Is that too much?
Marion: my recommendation is to dramatically reduce omega-6 intake, eat fatty fish 2-3 times a week and take 1/2 to 1 tsp. of fermented cod liver oil per day for all of the reasons I described in this article.
– You really didn’t clearly answer this person’s question. Kind of like how you’ve been mildly evading being straight on some of your other responses here, particularly the ones that question your position on this.
It’s also pretty interesting to me, Chris, that the correlation outcomes you’re presenting here are similar to the correlation presented in the meat causes cancer studies; the ones you spent an hour on a podcast picking apart and criticizing. I agree with you there, and eat red meat everyday. But I can’t agree with you on fish oil.
I have been taking fish oil for my arthritis — 3600 mg daily. I am 61 and was an avid distance runner until felled by hip arthritis (now both sides). I had stopped running entirely and was in such pain that I had scheduled hip replacement surgery for last August. I read an article about 5 months ago, however, that said that most people fail to benefit from fish oil because they do not take enough. By the time I had my pre-op visit with my surgeon, my arthritis have improved markedly — so much so that my surgeon was no longer willing to do the surgery. I was able to begin running again with my running group (3 miles on trails) and had significantly less pain. From my reading of the scientific literature, fish oil has been associated with relief from joint pain (due to its anti-inflammatory properties and other unknown effects). Would you recommend from your assessment of these new findings that I stop or reduce my intake?
Best to just eat fatty fish 2-3 times a week, and take 1/2 tsp/day fermented cod liver oil from Greenpasture.org.
Hi Chris,
What is the dose recommended of omega 3 caps? 1 gram a day???
Chris,
thx for another great article.
Prof. Brian Peskin has been advocating agains fish oils for a long time, more info
http://www.brianpeskin.com/
Also google ‘IOWA study on fish oils’, and you also see that fish oils makes worse
B.Peskin has been advoacing for consuming good ratio of omega 3:6, and then body would be able to produce enough DHA and EPA. Whilst consuming fish oils we get pharmacological doses of DHA and EPA, which is harmful, could even lead to diabetes, CVD, cancer.
He got a term parent essetial oil (PEO), – which basicly means high quality omega 3 and 6 (alfa linolenic and linoleic fatty acids)
Unlikely it would lead to cancer, since it suppresses inflammation and cancers use inflammation to invade healthy tissue and hide from the immune system; omega 6 prostaglandins promote inflammation and also suppress production / activity of natural killer white blood cells which are the first line of defense against cancer cells. Since oils compete with each other absorption of more omega 3 would mean less omega 6 and its inflammatory effects, etc. (John Boik, Cancer and Natural Medicine for all of the above). Please elaborate on what the theory might be for how omega 3 would do this.
Chris, yes of course. I was so focused on toxins exceeding safe levels or allowable limits, that I completely misread the “standards” part. Thanks for your insight re: FCLO.
Suzy: exceeds the standards means “is better than”.
Eating vitamins in their natural whole food form is always the best choice. When supplementing, D3 is more desirable than D2, but that doesn’t mean we would avoid cod liver oil because it has more D2 than D3. As I said in my previous reply, there’s still a lot we don’t understand about the various constituents and how they work together.
Chris, thanks for your reply. So now I’m confused because from my understanding it’s the D3 we’re after. I was hoping to use FCLO as a somewhat whole food source of vitamin D (more for maintenance than boosting my levels). But now it looks like it’s actually the wrong kind of vitamin D? Could you please shed some light on this for me?
As for the second part about Prop 65, that’s what I was worried it meant, but was hoping that I had misunderstood it. I’m surprised to hear that their FCLO exceeded the standards. I always thought that FCLO was one of the “safer” alternatives. Could you please share your thoughts on this?
Thank you.
Suzy: it has D2 because that’s what naturally occurs in the cod livers, apparently. We know less than we think about how all of the various constituents of vitamin and mineral complexes behave.
The second part means that the detectable levels of PCBs exceed the WHO and California Prop 65 standards.
From the Green Pastures link you posted for their “Product Test Data” – under additional comments it says “Majority of D is D2”. I’m concerned – I thought it would’ve been D3 – do you know why that is?
Also, do you know what this means: “below .090 PPM PCB WHO/exceeds Prop 65” ?
Thanks for the very informative post.
Hi Chris, an interesting counter-point here…but I have not read the full study, just the abstract. Frankly, I wasn’t even aware of this journal.
Mas E, Woodman RJ, Burke V, et al. The omega-3 fatty acids EPA and DHA decrease plasma F(2)-isoprostanes: Results from two placebo-controlled interventions. Free Radic Res. Jun 2010.
http://bit.ly/dlzLHd
Bentzurm,
Yes, that would be wise. I did mention the omega-3 index in this article. Scroll down about 2/3 of the way.
Chris,
You have not mentioned the omega3-index blood tests in your excellent fish oil posts. Would you agree that the following would be wise:
– reduce dietary omega6 to a minimum, while taking moderate amounts of fish oil (or FCLO) for 6 months (to reverse years of SAD).
– test your membrane fatty profile and either increase or decrease fish oil accordingly.
– retest in 6-12 months and repeat.