Is Fish Oil Just a Massive, Artery-Clogging Scam?
Aug 2012 04
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A wealth of research shows this stuff may just save your life. But certain Internet commentators claim the exact opposite. Why?

Walter M recently wrote to object to my last Reader Mail segment, which discussed the primacy of calories in weight loss and the virtues of fish oil for CHD prevention. His email has been reprinted in its unedited entirety below (by the way, why is it that people who disagree with me invariably have poorer grammar and spelling than those who don't? Just sayin'...)

Walter writes:

Just a few gripes with some of your claims:

1. Obesity and calories

Taubes has spoken about those studies on people eating under the daily recommended amount of calories (malnourished) and were doing hard physical labour for their jobs yet were overweight (Chilean factoryworkers). Also there is that 2010 study of a calorie restricted diet vs low carb calorie unrestricted diet and the low carbers lost just as much weight (1). Both of these things seem to threaten the 'lazyness and overeating' theory of obesity, no?

2. Fish oil

Plenty of people are claiming that fish oil is doing good things for cardiovascular health but a study of 42,612 people found that it 'provided no significant benefits to CHD risk among study participants' (2). They even seem to clog arteries (3). Ray Peat has written a heap about the fish oils and it looks like not only a massive con but something that is pretty bad for us(4).

3. Fat

You say that 'fat doesn't make you fat'. The horeshite about saturated fat certainly belongs in a grave but I'm not so sure we can dismiss all types of fat as having that harmless (and protective) effect. The polyunsaturated fats seem like they might be the main culprit behind obesity. Paul Jaminet has some interesting graphs(5) showing their consumption has increased in proportion with the obesity epidemic. While that doesn't prove shit, the effect they have on animals - as pointed out again by Ray Peat- makes them suspect number one as far as I'm concerned. Ray has some good articles on the polyunsaturated fats on his site:

"Linoleic and linolenic acids, the "essential fatty acids," and other polyunsaturated fatty acids, which are now fed to pigs to fatten them, in the form of corn and soy beans, cause the animals' fat to be chemically equivalent to vegetable oil. In the late 1940s, chemical toxins were used to suppress the thyroid function of pigs, to make them get fatter while consuming less food. When that was found to be carcinogenic, it was then found that corn and soy beans had the same antithyroid effect, causing the animals to be fattened at low cost. The animals' fat becomes chemically similar to the fats in their food, causing it to be equally toxic, and equally fattening.(6)

4. Thanks for introducing me to Sara Varone.




Anthony replies:

Sorry Walter, but you lost me the moment you cited Gary Taubes.

1. "Taubes has spoken about those studies on people eating under the daily recommended amount of calories (malnourished) and were doing hard physical labour for their jobs yet were overweight (Chilean factory workers). "

Taubes speaks all sorts of gobbledegook that has no foundation in reality. But of course, he took these Chileans, placed them in a metabolic ward, scrupulously controlled their food intake, and was able to confirm they were indeed metabolic freaks of nature who were able to gain weight despite consuming below their caloric needs, right?

Yep, don't listen to me Walter - keep ignoring the mountain of tightly controlled ward evidence showing calories are the ultimate arbiter of weight status, and keep citing dodgey anecdotes about Chilean factory workers instead. You know, just like Taubes does.

"Also there is that 2010 study of a calorie restricted diet vs low carb calorie unrestricted diet and the low carbers lost just as much weight (1)."

Um, is this some kind of joke? This was a free-living study, not a ward study. Once upon a time (2007) in a far away land called Glen Waverly, I wrote a book called The Fat Loss Bible (rumour has it the book was preserved by truth-seeking monks passing through Melbourne on a never-ending journey towards enlightenment, and subsequently made available on Amazon and Lulu). This not-so-mystical book explains in detail how researchers ultimately have little control over what the participants in free-living studies really eat, and how misreporting of dietary intake is well known to be rife in these studies - and how under-reporting is most common in those assigned to low-fat and calorie-restricted diets. But heaven forbid you actually read my referenced thoughts on the matter before writing to dispute me, that would be way too commonsensical a thing to do.

2. "Plenty of people are claiming that fish oil is doing good things for cardiovascular health but a study of 42,612 people found that it 'provided no significant benefits to CHD risk among study participants' (2)."

The study you cite was an epidemiological study (and, for the record, it surveyed cod liver oil consumption, not stand-alone fish oil supplements). Randomized, controlled clinical trials - which are not hopelessly prone to all the confounders that epidemiological studies are - have found significant benefit for fish oil supplements and purified long-chain omega-3 fats.

Walter, seriously, why do you waste my time with this epidemiological nonsense? Did you even bother to read the recent Reader Mail in its entirety? You know, including the bit about what a complete uber-wank modern nutritional epidiemiology is?

But if you are going to cite epidemiological studies, you could have mentioned the multitude of population studies showing fish eaters to have significantly lower rates of CHD. Of course, you ignored them all and cited the one that you (erroneously) think supports your Peatian beliefs.

"They even seem to clog arteries (3)."

Right. Which is why they have been shown in large clinical trials to lower CHD mortality (GISSI, DART, JELIS). Yeah, that makes sense: fish oil clogs arteries but lowers CHD mortality.

Lawdy lawdy...

Did you even read the Felton study you referenced?

I think we both know the answer to that.

So let me explain it to you: It was not a clinical trial that fed volunteers fish oil, but a post-mortem "snapshot" study that examined plaques in a grand total of 9 male subjects who had not been subject to any specific dietary intervention. It simply found that the plaque content of n-6 linoleic acid and the n-3 docosahexaenoic acid (DHA) were associated with blood levels of the same fatty acids.


That's a far cry from claiming n-3 fatty acids actually block arteries. The above study is useful in that it helps debunk the moronic Sunday-paper view of atherosclerosis, which would have us believe atherosclerotic plaques are just big blobs of saturated fat and cholesterol that come waddling down the arteries before picking a comfy spot on the artery wall to settle down and form an atheroma.

But as proof that n-3s cause atherosclerosis, the Felton study doesn't qualify. Especially when randomized clinical trials in which patients were actually assigned to either fish oil or placebo treatments experienced improved arterial outcomes.

For example, Thies and co-workers assigned patients waiting to undergo carotid endarterectomy in double blind fashion to consume 6 grams daily of either a control oil (containing 80:20 palm/soybean oil), sunflower oil, or fish oil.

And what did they find?

"Fewer plaques from patients being treated with fish oil had thin fibrous caps and signs of inflammation and more plaques had thick fibrous caps and no signs of inflammation, compared with plaques in patients in the control and sunflower oil groups..."

In other words, the fish oil subjects had plaques with thicker, more robust fibrous caps that were less likely to rupture, block an artery with the spewed-forth contents, and trigger a coronary event. Let me make this even clearer:


von Schacky et al administered a placebo or fish oil to CHD patients and while no differences in carotid artery thickness were noted, they observed that regression of coronary artery thickness was more than twice as common in the fish oil group. Fish oil recipients also had fewer cardiovascular events.


Cawood et al from the UK recently administered placebo or esterified n-3 capsules to patients awaiting carotid endarterectomy. While some inflammatory markers improved in the n-3 group, actual plaque morphology or stability was not different between the 2 groups. However, the mean duration of administration was only 21 days, so it's quite possible the "anti-inflammatory" actions of the n-3s didn't have enough time to exert actual physical changes. However, the researchers did note that higher plaque eicosapentaenoic acid (EPA) content was associated with less inflammation and increased plaque stability. The exact opposite of what you deduced from the Felton abstract.

Japanese researchers recently analysed plaques from angiography patients and found that "patients with acute coronary syndrome had significantly lower levels of n-3 PUFAs (especially of EPA and DPA) than those without it" and that "even after adjustment for confounders, the presence of both low EPA and low DPA levels proved to be an independent predictor for lipid-rich plaques..." Again, this flatly refutes what you have chosen to believe from the Felton study (or more likely, your uncritical acceptance of Peat's interpretation of it), doesn't it?

There's also a plethora of studies showing fish oil improves arterial function:

And while I personally recommend conservative doses of fish oil, it was recently found that highly purified EPA was effective in decreasing the incidence of CAD among Japanese patients with diabetes/impaired glycemia (22% RR reduction), even though their intake of fish was high.

I could go on and on, but suffice to say a review of the research to date, recently published in the British Journal of Nutrition, has concluded:

"...marine omega-3 fatty acids are effective in preventing cardiovascular events, cardiac death and coronary events, especially in persons with high cardiovascular risk."

As for safety, a recent review of the various mechanisms of action exerted by fish oil/long-chain n-3s concluded:

"n-3 PUFA decreased several risk factors for atherosclerosis without any serious adverse effects..."

"Ray Peat has written a heap about the fish oils and it looks like not only a massive con but something that is pretty bad for us(4)."

Why thank you Walter, how nice of you to insinuate I'm involved in a massive con. Obviously another advanced graduate of The Pee Pee School of Social Diplomacy. I've long been recommending fish oil, and I've done so only because an extensive review of the scientific evidence has convinced me it's the right thing to do. For the record, I don't have - and never had - any financial stake in fish oil or any other omega-3 product.

And no offense to Ray Peat, I'm sure he's a nice guy who's sincere about what he does, and I have no desire to start a pissing contest with the bloke, but...if I'm going to place my future health in the hands of a couple of Internet articles that fail to discuss a boatload of contradictory research, or data from randomized controlled clinical trials, well...

Walter, if Gary Taubes and Ray Peat are your almighty Gods whose teachings you subscribe to with unquestioning faith, then good for you. If you have already decided they are the most convincing of dietary commentators and thus you no longer have to critically analyse anything they say, then please show some courtesy and don't waste my time with cocksure emails informing me of your "gripes" - gripes that I have already debunked a hundred times before. I hate to sound like a broken record, but it kinda irks me when people write pissing and moaning about stuff I've already explained in detail numerous times previously.

3. "The polyunsaturated fats seem like they might be the main culprit behind obesity."

Holy catfish, Batman...

For the umpteenth time, an increased calorie surplus is THE culprit behind obesity.

I have already discussed on this site that trials comparing isocaloric amounts of polyunsaturated fats versus other fats have shown no difference in weight gain or loss. Go to this link and read the last two Q&As:

If you still think isocaloric polyunsaturated oils still cause different bodyfat and weight outcomes, let alone explain the obesity epidemic, congratulations! Your fellow churchgoers will be truly inspired by your ability to remain steadfastly faithful in the face of a complete lack of scientific support.

4. "Thanks for introducing me to Sara Varone."

Um, Sara Varone, along with the entire female population of Italy, is a living, breathing contradiction to the teachings of your buddy Taubes. But I'm guessing you haven't made it past her cleavage...which is OK, you're only human and this is a perfectly forgivable transgression, yessirree. However, mindlessly subscribing to the untenable theories of your favourite diet gurus is not.

I used to think leopard print was a terribly tacky look no woman could successfully pull off.  I stand humbly corrected.

Folks, after ploughing through the evidence, I've come to my own conclusions about fish oil. For the rest of you trying to decide whether fish oil will help or kill you, I strongly suggest you review the scientific evidence first hand rather than other people's questionable interpretation of it.

Anthony Colpo is an independent researcher, physical conditioning specialist, and author of The Fat Loss Bible and The Great Cholesterol Con. For more information, visit or

Copyright © Anthony Colpo.

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