# Fish Oil

Category: Foods & Substances

Also known as: omega-3, EPA, DHA

Fish oil, rich in the highly unsaturated fatty acids EPA and DHA, is not an essential nutrient but a metabolic toxin whose apparent short-term benefits derive from its rapid oxidative breakdown. Peat argued that the original 1929 experiments by the Burrs claiming essentiality…

11 passages · 1 author · 2008–2022 · Most-cited: [Ray Peat](https://bioenergeticoracle.com/md/voices/ray-peat/index.md)

Canonical page: https://bioenergeticoracle.com/concepts/fish-oil

## Synthesis

**Fish oil**, rich in the highly unsaturated fatty acids EPA and DHA, is not an essential nutrient but a **metabolic toxin** whose apparent short-term benefits derive from its rapid oxidative breakdown. [Source 1, 3, 7] Peat argued that the original 1929 experiments by the Burrs claiming essentiality for linoleic and linolenic acids were later disproven when the deficiency disease was cured by **vitamin B6** rather than fats. [Source 4] The long-chain omega-3 fats found in fish oil possess five and six double bonds, making them exponentially more unstable than seed oils. [Source 3] This extreme instability means a large portion spontaneously oxidizes before even reaching the bloodstream, and it is these *oxidative breakdown products* that exert the celebrated anti-inflammatory effect by directly suppressing white blood cells and the immune response. [Source 3, 10, 11]

The anti-inflammatory action is fundamentally an **immunosuppressive** process analogous to the historical use of X-ray therapy for inflammatory diseases. [Source 5, 6, 11] Peat noted that for the first few months, fish oil interferes with prostaglandin synthesis and inflammatory cytokines, providing symptomatic relief. [Source 3, 5] However, after approximately six months of continuous use, this effect transitions into a broader immune deficiency, increasing susceptibility to infections and, over a lifetime, contributing to cancer and degenerative conditions. [Source 3, 11] The oils' toxicity is not limited to immune cells; they exert *antithyroid*, *antimitochondrial*, and *lipid peroxidative* effects, directly suppressing mitochondrial respiration and glucose oxidation. [Source 1, 2, 5]

Chronically, the accumulation of these fats drives the aging process itself. Peat highlighted that the **age pigment lipofuscin** forms from the peroxidation of polyunsaturated fats, and fish oils are particularly potent inducers of this process in the brain, arteries, and liver. [Source 1, 3] In the brain, the concentration of these highly unsaturated fats correlates negatively with function; healthy newborns are metabolically "deficient" in them, while Alzheimer's patients exhibit markedly elevated levels of the oxidized neuroprostanes. [Source 3, 6] In the cardiovascular system, the fats form stabilized esters with cholesterol in atherosclerotic plaques, where their eventual oxidation contributes to arterial damage, contradicting the rationale that they prevent heart disease simply by lowering blood lipids through a toxic effect on the liver. [Source 1, 3]

The commercial promotion of fish oil parallels earlier industry-driven campaigns for seed oils and radiation safety, with government agencies and journals selectively amplifying favorable research while ignoring contrary evidence. [Source 2, 9] Peat maintained that the only arguable benefit of omega-3 fats is that their extreme instability causes them to break down so rapidly that they are less easily stored as a chronic problem compared to the more stable omega-6 seed oils, and they can partially displace those seed oils in tissues. [Source 8] In practice, he recommended strictly limiting all polyunsaturated fat intake, identifying **olive oil**, **coconut oil**, and **butter** as the safest dietary fats, with olive oil still warranting moderation due to its 10% PUFA content. [Source 6, 8]

## People also ask

### How does fish oil suppress inflammation according to Peat?

Peat argued that fish oil's anti-inflammatory effect comes from its oxidative breakdown products, which directly suppress white blood cells and the immune response, acting as an immunosuppressant rather than a beneficial nutrient.

### Why did Peat consider fish oil a metabolic toxin?

Peat described fish oil as a metabolic toxin because its highly unstable EPA and DHA fats rapidly oxidize, producing compounds that suppress mitochondrial respiration, interfere with thyroid function, and drive lipid peroxidation throughout the body.

### What fats did Peat recommend instead of fish oil?

Peat recommended strictly limiting all polyunsaturated fats and identified olive oil, coconut oil, and butter as the safest dietary fats, though he advised moderation with olive oil due to its 10% PUFA content.

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- [Orange juice](https://bioenergeticoracle.com/md/concepts/orange-juice/index.md)
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- [Age Pigment (Lipofuscin)](https://bioenergeticoracle.com/md/concepts/age-pigment-lipofuscin/index.md)

## Cited passages

Passage numbers match the `[Source N]` markers in the synthesis above.

### Source 1 — The Great Fish Oil Experiment

Ray Peat · Article · 2008 · https://raypeat.com/articles/articles/fishoil.shtml

> The most popular way of arguing that fish oil will prevent heart disease is to show that it lowers blood lipids, continuing the old approach of the American Heart Association's "heart protective diet." Unfortunately for that argument, it's now known that the triglycerides in the blood are decreased because of the fish oil's toxic effects on the liver (Hagve and Christophersen, 1988; Ritskes-Hoitinga, et al., 1998).
>
> In experiments with rats, EPA and DHA lowered blood lipids only when given to rats that had been fed, in which case the fats were incorporated into tissues, and suppressed mitochondrial respiration (Osmundsen, et al., 1998).
>
> The belief that eating cholesterol causes heart disease was based mainly on old experiments with rabbits, and subsequent experiments have made it clear that it is oxidized cholesterol that damages the arteries (Stapran, et al., 1997). Since both fish oil and oxidized cholesterol damage rabbits' arteries, and since the lipid peroxides associated with fish oil attack a great variety of biological materials, including the LDL lipoproteins carrying cholesterol, the implications of the rabbit experiments now seem very different.
>
> Another way of arguing for the use of fish oil or other omega-3 fats is to show a correlation between disease and a decreased amount of EPA, DHA, or arachidonic acid in the tissues, and to say "these oils are deficient, the disease is caused by a deficiency of essential fatty acids." Those oils are extremely susceptible to oxidation, so they tend to spontaneously disappear in response to tissue injury, cellular excitation, the increased energy demands of stress, exposure to toxins or ionizing radiation, or even exposure to light. That spontaneous oxidation is what made them useful as varnish or paint medium. But it is what makes them sensitize the tissues to injury. Their "deficiency"
>
> in the tissues frequently corresponds to the intensity of oxidative stress and lipid peroxidation; it is usually their presence, rather than their deficiency, that created the disposition for the disease.
>
> One of the earliest harmful effects of polyunsaturated fatty acids, PUFA, to be observed was their acceleration of the formation of lipofuscin or ceroid, the "age pigment," during oxidative stress or vitamin E deficiency.

### Source 2 — The Great Fish Oil Experiment

Ray Peat · Article · 2008 · https://raypeat.com/articles/articles/fishoil.shtml

> # The Great Fish Oil Experiment
>
> Reading medical journals and following the mass media, it's easy to get the idea that fish oil is something any sensible person should use. It's rare to see anything suggesting that it could be dangerous. During the recent years in which the U.S. government has gone from warning against the consumption of too much of these omega-3 oils ("to assure that the combined daily intake of two fatty acids that are components" "(i.e., eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) would not exceed 3 grams per person per day (g/p/d)") to sponsoring biased industry claims, there has been considerable accumulation of information about the dangers of fish oils and omega-3 fatty acids. But there has been an even greater increase in the industry's promotional activities. The US government and the mass media selectively promote research that is favorable to the fish oil industry. The editorial boards of oil research journals often include industry representatives, and their editorial decisions favor research conclusions that promote the industry, in the way that editorial decisions in previous decades favored articles that denied the dangers of radiation and reported that estrogen cures almost everything. Marcia Angell, former editor of the NEJM, has observed that the "significant results" reported in published studies can be properly interpreted only by knowing how many studies reporting opposite results were rejected by the editors. One way to evaluate published studies is to see whether they tell you everything you would need to know to replicate the experiment, and whether the information they provide is adequate for drawing the conclusions they draw, for example whether they compared the experimental subjects to proper control subjects. With just a few minimal critical principles of this sort, most "scientific" publications on nutrition, endocrinology, cancer and other degenerative diseases are seen to be unscientific. In nutritional experiments with fish oil, controls must receive similar amounts of vitamins A, D, E, and K, and should include fat free or "EFA" deficient diets for comparison.

### Source 3 — Ray Peat Interview with Tucker Goodrich, David Gornoski on PUFAs, Seed Oils, Benefits of Sugar, Milk

Ray Peat · Interview · Apr 8, 2022 · https://www.youtube.com/watch?v=PR5OqIPNZo0

> **Tucker Goodrich:** Right. Now, so that gets another controversial position that you... hold and i will you know with the caveat that if assuming i understand it correctly let me describe what i understand is that you caution people against excess fish oil intake clearly omega-3 fats are also susceptible to lipid peroxidation just like omega-6 fats are much more so Much more so, okay. So do you want to describe your position on that so I don't mangle it?
>
> **Ray Peat:** It's the number of double bonds, and the fish oil is extremely rich in five and six double bonds, where the seed oil, N-6 vegetable oils typically have two or three double bonds. Those are sufficiently toxic. But when you get five or six double bonds in a molecule, the instability is that much greater. The anti-thyroid effect of the fish oil, very highly unsaturated, is that much greater than the seed oil. But the good thing is that they are so unstable that a large part of them breaks down before they even circulate to your tissues. And it's the breakdown products, the oxidation fragments of the N-3 fish oil type of PUFA that has the so-called anti-inflammatory effect. It's toxic to your immune system to the extent that for the first few months you can see a definite anti-inflammatory effect by interfering with things such as prostaglandin synthesis and some of the inflammatory cytokines and breaking down thymus cells that could be involved in inflammation. But the trouble is that prolonged use after about six months this anti-inflammatory effect starts becoming immunosuppressive and over a lifetime the amount of the long chain highly unsaturated and minus three accumulates stabilized to some extent by forming an ester with cholesterol molecules. And that happens in atherosclerotic plaques in the arteries. And then when it does oxidize, forming age-pigment-like material in your arteries, that's part of the buildup of the high cholesterol-containing but it's the PUFA esters that start the process of forming age pigment and or arterial plaques. But that process continues in the brain so that the old person's brain has much more fish oil-like molecules. The baby's brain, any healthy pregnancy, delivers a baby who is, according to the dieticians, deficient in the so-called essential fatty acids. Their body is burning calories at two or three times the rate of an older individual, and their brain is learning at several times higher rate than an adult.

### Source 4 — Life Supporting Substances Its Rain Making Time 2011 07 04

Ray Peat · Interview · Jul 4, 2011 · http://l-i-g-h-t.com/files/rarinmaking-time-life-supporting-substances.mp4

> **Ray Peat:** The way a lot of these people are reasoning is to identify the fish oils, DHA and EPA, as essential fatty acids, or the omega-3 oils as essential fatty acids, and then say, "Since they are essential nutrients, they can't be toxic." Some of the articles on my website deal first with that issue of essentiality, and show that the basic studies that are still being cited were done in 1929 by George Burr and his wife. And at the time they published their results, they neglected to mention (several very well known articles were published in the same journal they published in) studies showing that those very fats that the Burrs were claiming to be essential nutrients were actually life-shortening ingredients in the diet. One study, two years before they published, showed that a fat-free diet eliminated almost all cancers in their experimental animals, as well as slowing the aging process. But they just ignored the contrary evidence and pronounced that linoleic and linolenic acids were essential to prevent a certain disease in rats (scaly tail disease, bloody urine, and such). It was about 16-17 years later that Roger Williams’ Lab in Texas (they had been studying the B-vitamins) recognized the Burrs' rat disease as a vitamin B6 deficiency disease. And vitamin B6 wasn't even known at the time the Burrs where giving their rats the specialized diet. So, Roger Williams Lab gave exactly the same diet the Burrs had used, and created the deficiency disease – “essential fatty acid deficiency symptoms” - and then, without adding any fats at all, they gave the rats vitamin B6 and cured the Burrs' deficiency disease.

### Source 5 — The Great Fish Oil Experiment

Ray Peat · Article · 2008 · https://raypeat.com/articles/articles/fishoil.shtml

> The original "essential fatty acids" were linoleic, linolenic, and arachidonic acids. Now that the toxic effects of those are coming to be recognized, new "essential fatty acids," the omega-3 fatty acids, including those with long chains, found in fish oils, are said to make babies more intelligent, to be necessary for good vision, and to prevent cancer, heart disease, obesity, arthritis, depression, epilepsy, psychosis, dementia, ulcers, eczema and dry skin.
>
> With just a normal amount of vitamin E in the diet, cod liver oil is certain to be highly oxidized in the tissues of a mammal that eats a lot of it, and an experiment with dogs showed that it could increase their cancer mortality from the normal 5% to 100%. Although fish oils rapidly destroy vitamin E in the body, some of them, especially the liver oils, can provide useful vitamins, A and D. In studies comparing fish oil diets with standard diets, these nutrients, as well as any toxins besides fatty acids (Huang, et al., 1997; Miyazaki, et al., 1998) in either type of oil, should be taken into account, but they seldom are.
>
> Despite the nutritional value of those vitamins, fish oils are generally much more immunosuppressive than the seed oils, and the early effects of fish oil on the "immune system" include the suppression of prostaglandin synthesis, because the more highly unsaturated long chain fats interfere with the conversion of linoleic acid into arachidonic acid and prostaglandins. The prostaglandins are so problematic that their suppression is helpful, whether the inhibition is caused by aspirin or vitamin E, or by fish oil.
>
> Some of the important antiinflammatory effects of fish oil result from the oxidized oils, rather than the unchanged oils (Sethi, 2002; Chaudhary, et al., 2004). These oils are so unstable that they begin to spontaneously oxidize even before they reach the bloodstream. In experiments that last just a few weeks or months, there may not be time for cancers to develop, and on that time scale, the immunosuppressive and antiinflammatory effects of oxidized fish oil might seem beneficial.

### Source 6 — The Science Behind The Dangers of Polyunsaturated Fats - East West Healing and Performance Interview (hosted by Josh and Jeanne Rubin)

Ray Peat · Interview · 2011 · https://www.youtube.com/watch?v=_AK-uiCWZPk

> **Jeanne Rubin:** In regards of Omega 3s, they produce non-inflammatory prostaglandins. I wanna get your take on that, do we need Essential Fatty Acids to produce prostagladins and fight inflammation or is that untrue?
>
> **Ray Peat:** Some of the recent work on the anti-inflammatory effect of the fish oil, or the Omega -3 fats, shows that they accumulate with aging, for example in the brain. And Alzheimer's or Dementia patients have a much higher level of these in the brain. They spontaneously oxidize into, not only toxic anti-metabolic, anti-brain-tissue substances (the neuroprostanes for example), but, in the process of oxidizing, they supress the immune system too. It's an across the board toxic effect. But when you look at the immune system, supressing the cells that produce inflammation, you get an interruption of an existing inflammatory process. Several researchers have found that it's only the oxidized form, the broken down form of the fish oils, that has the anti-inflammatory effect. When you prolong the feeding with this anti-inflammatory effect, you start seeing that immunodepression is the longer range effect. The present extreme advocacy of fish oil for its anti-inflammatory effect is very similar to what the X-Ray industry was doing 80 years ago, even as recently as 1950s and 60s; they were still treating arthritis, acne, psoriasis, ringworm, anything with an inflammatory component, with X-rays treatment, because it's immediate effect is to create these lipid peroxides, which are anti-inflammatory, immediately immunosupressive in the long run, and toxic in many ways, eventually.

### Source 7 — One Radio Network: Patrick Timpone: Dr. Peat Answers Questions Regarding Health, Diet and Nutrition Part 2

Ray Peat · Interview · Jan 1, 2014 · http://www.l-i-g-h-t.com/files/one-radio-network-patrick-timpone-dr-peat-answers-questions-regarding-health-diet-and-nutrition-part-2.mp4

> ## Omega-3s and Fish Oil
>
> **Patrick Timpone:** William is a naturopathic doctor and wants to know what you think about Brian Peskin's claims that Omega-3s and fish oils are unnecessary.
>
> **Ray Peat:** Well, he's right about the fish oil. There's no evidence that it's an essential fat. But also, there's no evidence that I've seen that the "Parent Essential Oils" (PEOs) are needed either.

### Source 8 — One Radio Network: Health & Diet

Ray Peat · Interview · Dec 4, 2013 · http://l-i-g-h-t.com/files/one-radio-network-patrick-timpone-dr-peat-answers-questions-regarding-health-diet-and-nutrition-part-1.mp4

> **Caller:** Even a good fish oil?
>
> **Ray Peat:** Yes, the fish oils happen to be so unstable, they were used as varnish, they were easier to oxidise than soy oil. The same thing happens in the body, in the 1960s they were seeing when feeding too much fish to farmed animals, they got what was called “yellow fat disease” caused by the breakdown of PUFAs. It came out in the 1970s that the seed oil had been promoted to lower cholesterol, like corn oil etc, it turned out that they were causing heart disease as well as cancer, so that opened up the market for fish oil like EPA and DHA from fish oil. Their good feature is that they break down so fast that they aren’t so easily stored to become a chronic problem like the more stable seed oils.
>
> **Caller:** do we need these DHAs? Or will we make them. Do we need flax, primrose, etc
>
> **Ray Peat:** There is no definite clear evidence that any of these are essential fatty acids. The best thing I can say about the fish oils, or n-3 fatty acids, is that they can protect to some extent against the n-6 seed oils. But in themselves they have been associated with causing increased metastatic cancer, reduced brain size, brain edema, all of the degenerative conditions such as slowed conductions of the nerves. Some of these are turned into virtues like immune suppression, which is normally a bad thing. You can suppress your immune suppression which is a temporary reduction in inflammation. They also slow conduction, so in some conditions you can reduce arhytmia of the heart because you are desensitizing the heart, but it also slows your nerve conduction, and we don’t hear much in the mass media about the bad effects of the long fish oils.

### Source 9 — Politics & Science: Food Quality

Ray Peat · Interview · Jan 7, 2012 · http://l-i-g-h-t.com/files/politics-science-food-quality-59-mins.mp4

> **John Barkhausen:** I see. So it’s suppressing your immune system and that’s what’s getting rid of some of your symptoms perhaps.
>
> **Ray Peat:** Yeah. It is the free radical oxidative decomposition products that are circulating in your blood system and a very small part of it reaches your tissues as the original starting DHA and EPA.
>
> **John Barkhausen:** And, Raymond, would you like to touch – we’re talking to Raymond Peat, by the way – I should say that more often –endocrinologist and physiologist from Eugene, Oregon. And we’re talking about – mostly about fats today, but also we are talking about the marketing of them and the scientific research that’s gone into fats. And how much does the marketing affect the scientific research. The media seems to still be very down on saturated fats and still promoting unsaturated fats.
>
> **Ray Peat:** Yeah. They apparently have taken over the government because I see the government has basically a promotion of fish oil on their website.
>
> **John Barkhausen:** Well, would that be the – is that the FDA…
>
> **Ray Peat:** Yeah.
>
> **John Barkhausen:** Or what’s the website? Okay.

### Source 10 — Politics & Science: Two Hour Fundraiser I

Ray Peat · Interview · Feb 22, 2012

> ## Caller: Fish Oil and Omega-3 Supplements
>
> **Roger:** My question centers around omega-3 fatty acids. A couple of years ago I came across a supplement of whole salmon fish oil that contained omega-3s and it was touted as being a great supplement to help arthritis and lower triglyceride levels. Then I read your research, which sort of contradicted all of these things. I was wondering if you could elaborate on what you think the dangers are of taking supplements of fish oil. I've been seeing that these fatty acids are showing up in all kinds of organic products like organic milk and baby formula.
>
> **Ray Peat:** Someone two or three years ago analyzed the baby formulas and found that the great bulk of the omega-3 fat that had been added to it had broken down and was probably in a toxic form. So their worst feature is that they break down and oxidize very fast. A couple of researchers have looked for them in the blood at the time that they are having their anti-inflammatory actions and found that they had already broken down. Just between the mouth and the bloodstream they broke down into completely new chemicals which were what accounted for their anti-inflammatory effect. But those same breakdown products are what in the long run suppress the whole immune system and have a lot of other toxic effects. So the short-range anti-inflammatory effect I see as analogous to the anti-inflammatory treatments I used to give with X-ray or other radiation.

### Source 11 — One Radio Network: Great Monthly Talk with Ray Peat PhD (August 17, 2020)

Ray Peat · Interview · Aug 17, 2020

> **Patrick Timpone:** Dr. Ray Peat is with us, Patrick Timpone, OneRadioNetwork.com. We got started a little bit late. Can you hang around for a few minutes, Dr. Peat? Okay. You okay? Good. This is Kane in Bellevue, Washington. Can you please ask Dr. Peat to help me understand why high-dose PUFA fish oil seems to help so many thrive? For decades and for decades and going way back from athletes to brain injury, fish oil has helped and is helping many perform at high levels recover from severe brain injury. So I don't understand his negative approach to fish oils.
>
> **Ray Peat:** Oh, my negative approach, it would take a week or so to give the... sources explaining it, but the short version is that when you ingest highly polyunsaturated oil, it's like the problem with taking in a large amount of synthetic ascorbic acid. Any reducing and oxidizing catalysts that are present are going to cause an explosive degrading oxidation of these highly oxidizable molecules. Studies have found that by the time fish oil gets into your bloodstream, it's already highly oxidized. And it's these oxidized free radical breakdown products of the fish oil that suppress the white blood cells and knock down your immune reactions. So for the first six months, usually, you get these anti-inflammatory effects that seem very beneficial. But you've probably heard of the radon baths causing immediate relief from arthritis. And they used to give x-ray treatments, actually, to a sore knee joint, and you'd get immediate knockdown of the inflammation in an arthritic joint from the ionizing radiation. But the anti-inflammatory effects of a big dose of highly oxidizable fish oil is working by the same mechanism, knocking out the inflammatory white blood cells But the effect, six months later, the process starts showing up the harmful effects. The radiation damage continues for 20 or 30 or 40 years later, and there haven't been such studies with the polyunsaturated oil overdoses, but the same kind of damage occurs, and so you would expect the long-range damage. What they see is that immune deficiency begins setting in after about six months of continuous supplementation of things such as fish oil. And part of the argument in relation to the brain is that the brain contains a lot of these highly polyunsaturated fats.

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