Quit Taking Fish Oil

Fish oil is a concentrated source of DHA,  a very special type of omega-3 fat that we use in our neurons, in our eye and heart tissue, and in sperm. In fact, some 30 million Americans take fish oil supplements daily simply to be sure they get enough of this very important fat. But, even though DHA is very important to health, I want to explain why it is a mistake to take fish oil supplements in any form.
      DHA is one of several types of special fats known as omega-3 fats. Humans cannot make omega-3s from scratch, instead they must be part of our diet. Given that we cannot live without them, they are called essential fats. Plants make omega-3 fats but the types they make are shorter than DHA. When we eat plants rich in 3s, we elongate some of them into DHA but we do so very slowly. We can also get “pre-made” DHA if we eat wild fatty cold-water fish (such as salmon, mackerel, and sardines) because their diets are very rich in DHA. Given that DHA is needed in important parts of our bodies, such as our brain and heart, we have for many years been advised to eat significant amounts of DHA-rich seafood and/or take fish oil supplements to make sure we have enough DHA for our brain to function properly. Vegetarians, vegans, and those who do not eat seafood were (and frequently still are) told that they absolutely must take a DHA supplement to stay healthy.
      But times have changed. Fish oil supplements are no longer deemed to be good for us. This complete turnabout is the result of two main realizations (although there are others). First, research failed to show any health benefits in those taking fish oil and instead began to show harm. Second, DHA proved to be very reactive and forms a variety of basically rancid fats as it reacts. It is well known that rancid fats are toxic.

Many, many studies show that eating fish has health benefits, including a lower risk of heart problems. It made sense to assume that the same health benefits would accrue in those who took DHA-rich fish oil supplements instead of eating fish. But, unfortunately, fish oil failed to provide the same benefits. Instead one study found an increased risk of atrial fibrillation (a type of heart arrhythmia) and prostate cancer in people taking fish oil supplements regularly. A different study confirmed that fish oil supplements increase the risk of atrial fibrillation. A very large study found that 2 servings of DHA-rich fish a week in two years decreased mortality by 29%. In a follow up study, where participants took fish oil instead, no health benefits were found; in fact, it revealed a trend for greater mortality. Other large studies also concluded that fish oil did not reduce the risk of heart attacks and other “cardiovascular events.” In angina patients, fish oil instead increased the death rate. Animals fed fish oil developed more malignant arrhythmias.
      A very recent study found that mice fed fish oil were much more susceptible to infections such as tuberculosis, salmonella and listeria. When infected with a flu virus, mice taking fish oil ended up with viral load 7 times higher than mice not getting fish oil. And the mortality rate of the flu was much, much higher –a death rate of 47% compared to 10% in flu-infected mice taking fish oil. These are just a few of the studies that culminated in the current advice: People should NOT take fish oil supplements except in very special cases such as severe hypertriglyceridemia with danger of pancreatitis or in people whose diet is extremely poor (e.g. some types of tube feeding).

DHA is extremely beneficial but it is also very fragile and highly reactive. And when DHA reacts, it forms oxidized, troublesome fats. The speed of oxidation increases as the DHA is exposed to light, heat, and air. Even fish oil stored in the dark at near freezing (39F) can develop unacceptable amounts of “bad” fats within a month of storage. In studies, oxidized fats cause organ damage, inflammation, cancer, and atherosclerosis. Manufacturers use tests to measure the amount of oxidized fats in their fish oil but the standards used are based on palatability and taste, not on how they impact human health. Those tests do not measure all of the many types of oxidized fats and the limits set apply to the fish oil at time of bottling, not at time of consumption. As a result, fish oil supplements in reality are a mixture of beneficial fats, a variety of additives, and varying amounts of oxidized or toxic, rancid fats.
      In a Canadian study, half of supplements on the store shelf exceeded these “palatability” limits. A US study found that 27% of fish oil tested had twice the recommended amount of oxidized fat. In South Africa and New Zealand, more than 80% exceeded these levels. And in another study about half of the fish oil supplements tested failed, with another 20% already very nearly rancid even though years remained on their shelf life.

The problem in large part is that fish oil is usually produced in a way that increases the likelihood of oxidation. Most are made from small fish caught off the coast of Peru or Chile. The fish are processed into oil once on land, after having been exposed to light, heat, and oxygen for unknown lengths of time. This oil is then stored in large tanks before eventually being shipped off for further refinement which usually takes place in China. Refinement includes heating the oil to high temperatures (deodorization) intended to remove compounds that add undesirable taste. This heat treatment greatly speeds up oxidation of DHA. Fish oil intended for human consumption then gets shipped to the supplement manufacturer for additional treatment such as microdistillation to remove persistent toxins. In some cases, camouflaging agents (such as lemon flavor) are added to make the end product taste better but which unfortunately appear to accelerate the formation of “bad” fats. In the end, consumers generally cannot tell exactly where their fish oil comes from or how far it has travelled on its way to the store shelf. But even were this known, there is no way of knowing how the oil was processed or how many oxidized fats it actually contains.

 Conclusion: The studies do not tell us that taking fish oil is good for our health. Instead they strongly suggest that fish oil will increase our risk of heart problems, of cancer, or of catching a bad case of the flu. Most, if not all, of the fish oil contains rancid fats by the time we buy it and quickly develops more once we get it home. There is only one sensible response to these facts: Quit taking fish oil. Instead, eat a healthy diet with a good balance of essential fats from plant foods and to that, should you wish, add some wild, cold- water, fatty fish in moderate amounts.

P.S. Other types of DHA supplements have similar problems and in a subsequent blog, I’ll discuss why krill and algal supplements are not a better choice. And eventually a blog dealing with the mistaken notion that humans cannot make enough DHA and need to either eat fish or take DHA-rich supplements will also be forthcoming.

P.P.S. Interested in trying  a science-based yet traditional approach to eating? We have TQIDiet classes starting soon, and our schedule, a syllabus, and testimonials are posted here

NOTE: You are welcome to use my blog’s content for non-commercial purposes but only if if you attribute the work to me (Kathy Abascal) and link back to the blog. This work is licensed under a Creative Commons Attribution-Noncommercial 3.0 United States License.


About kathyabascal

Herbalist with a background in neurobiology, biochemistry, and law. Teacher of the TQIDiet, how to quiet inflammation with food.
This entry was posted in chemicals, Food, supplements and tagged , , , , , , , . Bookmark the permalink.

17 Responses to Quit Taking Fish Oil

  1. old TQIer says:

    Hello Kathy, We began taking Wild Alaskan Salmon Omega 3s in 2009, when you recommended it in TQI classes. Last week my primary care doc said I could “stop, because new research shows it does not benefit heart health.” Since we weren’t taking it for “heart health”, we thought it would be fine to continue. You’d made a very good case for Omega 3’s beneficial properties. Now this in your blog. So we should STOP the Omega 3’s now??? All this time we thought they were the secret to our good health. Guess it’s been the veggies all along.

    BTW, we continue to enjoy good health, and when we don’t stray too far from TQI we feel really well 😀

    With appreciation, a former student

    • kathyabascal says:

      I, like many, was convinced by the early research that fish oil supplements were a good thing. Now, having steeped myself in the research on essential fats, I am am convinced that omega 3 supplements, especially those containing DHA and EPA, not only are not good for heart heath, they are not good for you period. So, yes, I think you should stop taking omega 3 supplements.
      Of course, omega 3s are essential but you can and should get what you need from your diet. And yes, it is the veggies that carry the magic!

  2. Lucilla Sallabank says:

    Could you please add references to the above mentioned studies? Thanks

    • kathyabascal says:

      My blog is written for people trying to eat well. It is not an academic publication filled with footnotes and references,in large measure because as a rule, those who have access to research journals usually can access any articles of interest through a pubmed search.
      A good starting point, if you want to go deeper into this is Albert BB, Cameron-Smith D, Hofman PL, Cutfield WS. Oxidation of marine omega-3 supplements and human health. Biomed Res Inter 2013 ID 46921. They discuss oxidation of PUFA, the many compounds that are formed, the limitations of anisidine and peroxide value measurements in a very balanced, somewhat pro-fish oil manner. Or try Cameron-Smith’s Invited Commentary in J Nutr Sci 2015; 4:1-2 (Fishing for answers: is oxidation of fish oil supplements a problem?)
      Re the benefits of fish oil supplements, maybe begin with Sanders TAB. Plant compared with marine n-3 fatty acid effects on cardiovascular outcome: What is the vertict? Am J Clin Nutr 2014; 100supp:453s-458S. Given that fish oil is an important commodity, expect the opinions and research to be all over the board. When reading studies do remember to consider participants background health, overall diet, outcome measures, etc.

  3. Karen B says:

    What about raw cod liver oil and fermented cod liver oil. Are these any better than the other fish oils on the market?
    And can I really expect to get intact, healthy omega-3’s in, say, a can of Alaskan salmon. Or must it be fresh. If it’s fresh and I cook it, have I “killed” the omega-3’s in it?
    So many questions! But I always appreciate your unconventional point of view on nutrition issues.

    • kathyabascal says:

      I do not think that cod liver oil has any benefits over fish oil when it comes to getting LC-PUFA. In fact, many types of cod are challenged/endangered making it a bit more of a problem. Most cod liver oil is heavily refined and I’ve not seen any studies showing that fermented cod liver oil contains fewer persistent toxins or oxidized fats than non-fermented. Some “raw” producers (like Rosarita) make claims of that their oil is unrefined. They do not, however, detail how it is produced and I’m a bit put off by their pictures of a person fishing from a row boat — doubt you can support exporting cod liver oil supplements to the US based on that type of fishing. And the fact that they need to add rosemary extract and a synthetic vitamin E to their oil indicates they too are concerned that the oil tends to oxidize.
      Canning does generate heat due to pressure which is a problem so fresh is better. If eating canned, best if canned in olive oil or some other antioxidants are present. As fish is cooked, yes, things start to change, that is one of the reasons we always eat proportionately on the TQIDiet, so we are sure that we have antioxidants to help offset and help the body handle those types of issues.

  4. retiredlady04 says:

    I’ve been taking salmon oil capsules from Vital Choice, Bellingham, WA. They claim their source is wild Alaskan salmon.

    • kathyabascal says:

      I’m sure the Vital Choice fish oil is from wild Alaskan salmon. It probably is one of the better fish oil options but that still leaves questions about how long the fish were out of the water, how they were processed, etc. before becoming fish oil. As well, the fact remains that the rancidity measures (anisidine and peroxide values) do not reflect all of the oxidation products that result over time. Nor does it say anything about whether you would have been better off eating some salmon instead.

  5. Kim says:

    There is a short video of the well respected Jeffery Bland explaining the flawed and misleading research regarding fish oil’s ineffectiveness.

    • kathyabascal says:

      First, Jeffery Bland and functional medicine are strongly in favor of supplements so these sources are not entirely unbiased when it comes to fish oil.
      Second, the video that you refer has Bland criticizing a JAMA study because of its selection criteria. He claims that, assuming dosing is a critical issue, the study would only have looked at only 3 studies and would have found a benefit of fish oil in people with serious cardiovascular issues.
      He does not say that studies show fish oil is better than a diet that incorporates fish in those with serious cardiovascular issues. He does not say that studies show that fish oil is better than fish in heathier individuals. He does not say that there are not valid concerns about the effect of oxidized fats, especially long-chained polyunsaturated fats in the fish oils people are taking.
      Finally, while Bland has criticisms of Vasquez’ study, even he does not call the study misleading. He simply thinks other criteria should have been chosen for the study and, had that been done, different results might have obtained.

  6. Nancy Gregory says:

    What is your take on fermented cod liver oil?

  7. C. Clark says:

    About a month ago, I quit taking 1600 mg. of fish oil because of the negative research. Once I had stopped, I experienced nearly constant palpitations and swelling in one (previously injured) leg. The palpitations have recently subsided and the swelling seems to be improving, although it has been 4 or 5 weeks of support hose and elevating my leg. I have been wondering about rebound effects of abrupt cessation of fish oil supplementation. Have you heard anything? Or was there likely something else going on? I adhere to the diet pretty well (except for too much sugar, assuming that any sugar is too much sugar) and generally feel quite good, so this was a noticeable departure from my usual state.

    • kathyabascal says:

      I have not heard of anything similar. However, I imagine that this could happen if your diet was not rich enough in omega 3 rich foods, and too rich in magnesium-depleting omega 6s and sugar. It’s always a good idea to ease into changes, of course, because there is much we do not know.

  8. Common Sense says:

    Anything in a package is probably bad for you, pretty basic and easy to remember. It has been processed, stripping away key nutrients, likely preserved and altered with chemicals that are not “food”. The closer something is to how it comes from the ground the better. Not always practical but whole foods are have ‘everything’. Eat that way instead

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