Fishy links to multiple myeloma, NHL and leukemia

A blog reader, thank you!, sent me a study titled Dietary Fish Intake and Risk of Leukaemia, Multiple Myeloma, and Non-Hodgkin Lymphoma, published in “Cancer Epidemiology, Biomarkers & Prevention” in April 2004. The full study is available online, so I won’t load the post up with details that you can read for yourself, right here:


But, as always, a quick overview. The study is based on questionnaires, which always makes me wary, since there could be a million other unmentioned factors involved. But I decided to have a look at it anyway, since the findings might be relevant to us.


The researchers examined a total of 4175 controls, 914 leukemia cases, 287 myeloma cases, and 1408 NHL cases; these were participants in a study carried out between 1994 and 1998 in Canada. Interestingly, compared to controls, myeloma folks were older and less likely to have ever smoked. I have never smoked in my life, but I found this mention of non smoking rather puzzling. It almost seems to imply that smokers are more protected against getting myeloma…weird! As for the second point mentioned, I was diagnosed with MGUS in 1999, at age 38, then with SMM in 2005, at age 44 (okay, okay, so 44 is “older” compared to 38…!).


Now, for most of my life, my fish intake has been limited to occasional cans of tuna. Dreadful, I know. If only I could go back in time, I would eat tons of fish! Fact is, growing up, I simply didn’t like the taste of it…until I met Stefano, who is a gourmet cook…yes, the rather annoying but also wonderful type who can peer inside a nearly-empty fridge and come up with a scrumptious meal within minutes. Gotta love the guy. And boy, can he cook fish!


Anyway, back to the study. The Canadian researchers discovered that people who consumed greater proportions of their total energy intake from fresh fish had a significantly lower risk of each of the three types of cancer, and there was a significant dose-response for risk of leukemia and NHL. Furthermore, Those in the highest quartile for percentage of fat intake from fish were at lowest risk […].


Basically, the higher your weekly fish intake, the lower your risk of developing one of the LH cancers (=the three cancers combined).


Attention-grabber: There was no association between level of education and cancer status. Well, phew!, that is indeed comforting. Until now, I had been absolutely convinced there must be an association between my undergrad years at Harvard University, my subsequent grad school career and my myeloma… 😉


Discussion part of the study: The major conclusion of this paper is that increasing proportions of total energy and fat obtained from fresh fish seems to protect against the development of leukemia, NHL, and myeloma. For all cancer types, the strongest reduction in risk was associated with increasing proportion of total fat obtained from fresh fish. This supports the hypothesis that dietary fats provided by fish are the key to the protective effect of fish intake against LH and other cancers. Aha!


The study ends as follows: In summary, in a very large case-control study, we have found a strong protective effect of fresh fish intake for leukemia, myeloma, and NHL which is consistent with previous literature.


Okay, but here is a good question: how can we know if our freshly caught fish is contaminated or not? (Go read the part about the myeloma-attacked Japanese village on p. 5.) Indeed, for that matter, how do we know that anything we eat isn’t contaminated? Does the label “organic” (biologico, in Italian) really protect us enough? But I am getting off track, and besides, the implications of that question would provide enough fodder for an entirely separate post.


Interesting titbit: Animal studies have found that consumption of fish oils increases survival of animals with cancer. I glanced at the particular animal study (full text: listed in the bibliography, and it implies that fish oil, i.e., not fish fillets or whole bits of fish, was given to dogs with lymphoma. Fish oil


That is why I will stick to my free-from-contamination (!) daily fish oil capsules. But, about once a week, I will also eat fish caught by a small fishing cooperative off the coasts of Tuscany. At least, contaminated or not, the fish is fresh!


  1. Thanks for your – as usual interesting – article!

    I eat lots of fish and here I am – “the fish-eating-effect” has to be marginal, since the Scandinaviens do get MM exactly like everybody else…. Best regards from Oslo

  2. I wonder if it’s possible to make it even more precise and say that it’s the Omega 3 in fish oil that has the beneficial effect. If so, vegetarians can get by on flax oil. I know they are not the same thing but, if Omega 3 is the key, then it doesn’t matter which you take.

    I think I’ve just found the answer from the article. Here they discuss the ratio between Omegas 3 and 6. As I think you’ve noted in a previous post, Omega 6 is pro-inflammatory and is thought to promote MM via IL-6. Omega 3 suppresses Omega 6 and thus prevents allergic reactions such as asthma. The ideal dietary ratio is thought to be 1:2.

    “These long chain polyunsaturated n-3 fatty acids are thought to competitively inhibit the use of arachidonic acid, an n-6 fatty acid, for the production of eicosanoids (e.g., prostaglandins, leukotrienes). Eicosanoids derived from arachidonic acid have been associated with several carcinogenic processes including both tumor promotion and progression (11). A ratio of n-3:n-6 fatty acid intake 0.5 may be important in reducing cancer risk; however, Western diets tend to result in a much lower ratio”


  3. Hi Christine, yes, you are right, it’s not just our diet that had made us develop myeloma. I believe that a bunch of things combined make one cell go bonkers…and that is the origin of all this mess. Perhaps a virus, perhaps a bacterial infection, perhaps chronic inflammation of whatever…who knows?

    Quite true, Paul, and in fact I discussed the n-3/n-6 ratio in my page (and related posts) on Omega-3. And much more. We should not eliminate n-6 from our diets, of course, but we should try to achieve an ideal balance between the two omegas (and I quote from my Omega-3 page), i.e. 1:1, at the most 4:1. But the average North American diet, and probably European by now, ranges from 11:1 to 30:1.

    I really must try to achieve that. I wonder if it would make a difference. I must search for an n-3/n-6 food chart when I have time.

    🙂 Margaret

  4. Margaret-

    Thank you for writing about this study. I didn’t consume much fish pre my mm diagnosis but I now supplement with fish or cod liver oil daily. I continue to come across studies promoting omega-3 fatty acids and their many health benefits. Many of these studies discuss the importance of what you and Paul McKeen discuss, the omega 3-6 balance.

    As for possible toxicities, I recommend Carlson products due to their filtration process- pharmaceutical grade fish oil- Nordic Naturals is supposed to be pure as well.

    As for the fishy taste, Carlson offers a lemon flavored fish/cod liver oil in both bottle and capsule that is not fishy tasting.

    David Emerson

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