A Case of Lung Cancer Treated with Fish Oil

Carlson's Fish Oil

There’s an inverse relation between consumption of fish and fish oil and the incidence of cancer.

Is it possible however to cure cancer with fish oil? Maybe so: here is a report of a case of lung cancer treated with fish oil that resulted in tumor shrinkage of up to 90% in three years.


We present a case of a 78-yr-old man with malignant fibrous histiocytoma with multiple lesions in both lungs. Following diagnosis, he declined conventional chemotherapy and elected nutritional intervention by increasing intake of omega-3 fatty acids and lowering intake of omega-6 fatty acids. We estimated that he consumed 15 g of the long-chain omega-3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) per day, and the ratio of linoleic acid/long-chain omega-3 fatty acids in his diet was 0.81. Serial computed tomography scans and pulmonary x-rays revealed remarkably a slow and steady decrease in the size and number of bilateral nodules. He has no apparent side effects from consuming large quantities of fish and algae oils rich in DHA and EPA and he remains asymptomatic.

The report doesn’t give too many details about the man’s motivations for declining cancer treatment, although it can be suspected that he merely didn’t want conventional slash, burn, and poison cancer therapy, especially with its poor record at curing lung cancer. And doubly so at his age. He was an ex-smoker, and had quit 25 years before after smoking for 23 years.

The report also doesn’t say where he got the idea to treat his cancer with fish oil. It wouldn’t be the first thing I would think to do. However, before his diagnosis he’d been taking a number of nutritional supplements, including fish oil, as well as aspirin, glucosamine, and others, so he may have been simply more attuned to the possibility than others.

He consumed a high amount of omega-3 fatty acids, up to 15 grams a day, which, if he were consuming either cod liver oil or fish oil capsules, could amount to 15 teaspoons of CLO or  up to 15 large fish oil capsules, since 5 ml of fish oil contains around 1100 mg of omega-3 fatty acids. Yet he suffered no ill effects, such as bleeding. On the contrary, his tumors shrunk dramatically.

The tumors began shrinking within months, and in about 3 years time, had shrunk 80 to 90%, and he had no symptoms.

His macronutrients were measured and consisted of 18% protein, 34% fat, and 48% carbohydrate. (Personally, I would have cut way back on the carbohydrates and replaced them with fat.)

What we can learn from this case

The most obvious thing we can learn is that fish oil probably shrunk his tumors, all but completely curing him, as he refused conventional treatment and the only other change he made was to cut way down on omega-6 fatty acids from vegetable oils, which are known cancer promoters.

Studies on the association between fish consumption and cancer have been equivocal, with some finding an (inverse) association, and others not. The reason may be that many other factors difficult to account for are important, most notably the consumption of omega-6 fats. Not only is the absolute amount of omega-3 consumed important, but also the ratio of omega-6 to omega-3 fats. So even if someone ate fish regularly or took fish oil, if he consumed a high amount of vegetable oils, that could negate any benefit from fish.

Avoiding vegetable oils (industrial seed oils) may be the most important action you can take to improve the omega-6/3 ratio, that is, to decrease it. Unfortunately, most people are still under the impression that these oils are healthy, since the health establishment has recommended them over the past several decades for “heart health”. In reality, there’s nothing at all healthy about them.

These oils include safflower, corn, soy, and others, as well as margarine. Virtually all processed and fast food contains large amounts. Note that olive oil is not an industrial seed oil and is healthy.

Why omega-3 oils fight cancer is still the subject of research. For example, DHA, an omega-3 fat found in fish oil, induces dose-dependent cell death in leukemia cells in vitro. DHA also induces apoptosis (programmed cell suicide) in lung cancer cells. In animal models, “efficacy of n-3 fatty acids protection in colon cancer is well supported”.

One reason that aspirin prevents cancer may be that it blocks metabolism of omega-6 fats, which are inflammatory. Omega-3 fats are anti-inflammatory. So decreasing the omega-6/3 ratio may accomplish nearly the same thing.

In the 20th century, the ratio of omega-6/3 radically increased with the discovery of how to manufacture cheap industrial seed oils and the rise of processed food. Our paleolithic ancestors may have had a body ratio of omega-6/3 of 2:1 or 1:1, whereas ratios as high as 50:1 are seen in the Western world now. In fact, countries with less cancer such as Japan have much lower ratios than we do.

It’s estimated that this patient’s omega-6/3 ratio while consuming high amounts of fish oil was 0.73. While the American Heart Association recommends 2 to 4 grams a day of omega-3 fats for those people with high triglycerides, and to do so only under consultation with a doctor, the report on this man who cured his lung cancer emphasizes that his high consumption was “without symptomatic or laboratory side effects”.


It’s difficult to say what one case tells us about the odds of treating cancer with nutritional intervention only. However, it does seem to confirm that omega-3 fatty acids fight cancer, and omega-6 fats from industrial seed oils promote it.

BTW, if you supplement with fish oil, liquid fish oil is a better option than capsules.

For more on cancer prevention and living a long time, get my book, Stop the Clock.

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  1. Kindke says:

    very interesting, I do wonder if he stops taking the omega3 would the tumors come back?

    I especially like this part from the paper

    “but one tumor continued to slowly grow. When the long-chain omega-3 PUFA intake was increased to 15 g/day, shrinkage of the resistant lesion was observed.The observation that the single resistant lesion was sensitive to a higher dose of long-chain omega-3 PUFAs is suggestive of an omega-3 PUFA dose–response relationship.”

    the study also mentions he had “several non-melanoma cutaneous cancers removed surgically.” in 2004. To this I would wonder why the omega3 didnt fight those? Although we dont know how much sun the subject was getting.

    Still I definitely agree we should be managing our o3/o6 ratio and avoid industrial seed oils at every opportunity.

  2. Uncle Maffoo says:

    Even though this case does not prove that fish oil cures cancer (and it may not for all we know), it does give one the sense that increasing Omega-3s and decreasing Omega-6s is something good to do “just because.” More fish oil and less Crisco has virtually no downside, but potentially plenty of upside.

    Uncle Maffoo

  3. Rob H says:

    Very interesting post Dennis – like you I had never considered Omega 3s for cancer treatment, but this seems to be offer up an interesting new avenue of treatment. Following on from my recent comment in your Berberine post, where I described how I was advising my Mother on which supplements to take for her metastatic bone cancer, I do currently have her taking 1 x teaspoon of regular cod liver oil per day. I chose this conservative dose for her so as not to go overboard on the Vitamin A in cod liver oil, but maybe I will switch her to liquid fish oil instead (ie does not contain Vitamin A) so I can up her dose a bit.. In terms of her diet, she has very little Omega 6 (I switched her to olive oil, coconut oil and Kerrygold butter a while back) and she has very little processed food, so I’m hoping that will work in her favour. Thanks for the new perspective – your blog is great at continuously opening up these new opportunities – much appreciated! Rob.

  4. OCE III says:

    P.D., Do you take aspirin daily? What would you recommend to a 58y old who has been reading you for a year.

    • P. D. Mangan says:

      I take a low-dose aspirin nearly daily. Take a look at some of my posts on aspirin for a take on risk/benefit ratio.

  5. What about mustard oil then? Since it has an even better 3:6 ratio {https://plenteousveg.com/vegan-sources-omega-3/} will that be good to consume? Or would it qualify as an industrial oil because it is from the seed of the mustard plant?

    • Bill says:

      PurnenduAn interesting question Purnendu. I do not know the answer but any good response needs to consider the way that mustard seed is processed for oil as well as actual the plant seed source.

      Vegetable oils have to processed by extensive industrial processes to make them palatable ( eg Canola, Soy & corn )

      • Purnendu Nath says:

        Although this looks scarily low-tech… seems like this is ‘safe’. The max temperature reached in the primary pressing stage is only 35C.


        Hooray for mustard oil?

        • Bill says:

          Mustard is a major ‘break’ crop ( break from growing grains ) for some farmers in Australia. But these mustard seed is processed here in the same factories as canola oil.

          In a former career as an organic inspector I was perplexed & disturbed to learn that even organic mustard seed was was processed to oil in the same way. This involved significantly higher than 35 degree temperatures & also being ‘cleaned up’ with caustic soda !

    • P. D. Mangan says:

      Can’t say I’ve given any thought to mustard oil. As per the discussion with Bill, if it’s cold processed and high in omega-3, it may be fine. First thing I see when I google it is concerns about toxicity.

  6. Alan says:

    Hi Dennis, any thoughts on hemp oil for cancer or other general health benefits of hemp?

    • P. D. Mangan says:

      Hi Alan – a cursory look shows it has a relatively good omega-6/3 ratio. Not spectacular. I’m thinking you might get any desired any health benefits better with something else. The omega-3 fats in oils like hemp and flax seed require enzymatic conversion inside the body into DHA and EPA, the fats the body uses. The conversion process is inefficient though, so in my view it’s better to take fish oil directly to get these.

  7. ted says:

    I’ve read omega 3s push out glutathione out of cancer cells.

    Also read this about Alpha lipoic acid, very interesting

    https://www.ncbi.nlm.nih.gov/pubmed/20042414 – Revisiting the ALA/N (alpha-lipoic acid/low-dose naltrexone) protocol for people with metastatic and nonmetastatic pancreatic cancer: a report of 3 new cases.
    – a man with pancreatic cancer and metastases to the liver, treated with intravenous alpha-lipoic acid and oral low-dose naltrexone (ALA/N) without any adverse effects. He is alive and well 78 months after initial presentation.
    – GB, is alive and well 39 months after presenting with adenocarcinoma of the pancreas with metastases to the liver.
    – JK, who presented to the clinic with the same diagnosis was treated with the ALA/N protocol and after 5 months of therapy, PET scan demonstrated no evidence of disease.
    – RC, in addition to his pancreatic cancer with liver and retroperitoneal metastases, has a history of B-cell lymphoma and prostate adenocarcinoma. After 4 months of the ALA/N protocol his PET scan demonstrated no signs of cancer.

  8. Bill says:

    PD I was brousing the Vitamin K website today and found an article about vegetable oil s& medicines such as statins both being hidden causes of cardiovascular disease & diabetes. I went to the source and have been trying to make sense of the original article which is available free as a pdf.

    Among the oils it lists are canola & soy bean oil. But it is a very detailed long article. I am still trying to make sense of it. But thought you might wish to see it.


  9. Dom says:

    Is it important to take vitamin k2 along side fish oil, just as it is recommended to take vitamin k2 with vitamin d ?

    • P. D. Mangan says:

      I’m not aware of any specific connection between fish oil and vitamin K, although I do take both and think that most people should also.

  10. Sandra Reuben says:


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