THE BLOG
09/05/2013 02:33 pm ET | Updated Nov 05, 2013

Something Fishy About Omega-3's: Prostate Cancer, Fish Oil and Panaceas

Just when we thought we had found a supplement with unquestionable benefit, our hopes of insuring good health by religiously swallowing the right pill are dashed.

Several recent studies report increased prostate cancer risk among men with high blood concentrations of omega-3 polyunsaturated fatty acids, or PUFA's. These are the fatty acids found in salmon, mackerel, herring, lake trout, sardines and albacore tuna. Blood levels reflect dietary intake of omega-3's, something that has been promoted for the prevention of heart disease and cancer. Health-minded consumers have propelled annual fish oil sales to more than $6 billion in products and fortified foods.

You might wonder how fish oil got on our medical radar. And if you haven't, I have. It can be very instructive tracing the origins of any accepted health practice. The foundation of such practices often proves inadequate to support the burden of broad claims.

In the early 70s, Danish investigators noted a dramatically lower incidence of cardiovascular disease among the Greenland Inuit. (If your asking yourself why Danish scientists would be in a position to notice something about the Inuit in Greenland, it's not as weird as it sounds. Greenland is part of the Danish Kingdom and Denmark keeps meticulous public health records.) The Danes theorized that the relative absence of cardiovascular disease in the Inuit stemmed from their distinctive diet of almost exclusively eating fish loaded with omega-3's.

So I couldn't help but ask, if these Inuit have high omega-3 blood levels due to their diet, do they have a high prevalence of prostate cancer? So I did my homework and found that the Inuit do indeed have an extraordinary prevalence of prostate cancer. Extraordinarily low. Clearly the prostate-cancer omega-3 story is more complicated.

The Inuit data proved all the more interesting in light of the evolution of their health over the past 50 years. As so often happens, with the "westernization/modernization" of the Inuit lifestyle, the incidence of cancer has increased dramatically, except for one. Prostate cancer remains incredibly rare amongst the Inuit regardless of fish or omega-3 blood levels.

Why is this story worth telling?

This is not the first time a supplement has been embraced as a therapeutic agent and subsequently found to have no effect or a negative one. Vitamins A, C, and E, beta carotene and selenium supplementation in the absence of a deficiency have all proven ineffective or something that increased mortality.

There are two overarching reasons this keeps happening.

The reductive nature of Western science lends itself to a certain kind of thinking. If a population is observed to have a particularly low incidence of a disease, we study them in an attempt to define the one factor that might explain it. We attempt to isolate the therapeutic agent. In this iteration it is omega-3's.

The second cause of repeated disappointment in health supplements has to do with our unrealistic expectations. We have outsourced responsibility for our health. We don't want to change the way we live despite documentation that lifestyle is one of the most powerful determinants of health. In this regard we collude with the reductive scientific thinking.
We want to continue to do the same things and get a different result by swallowing a magic pill. Commercial interests understand this very well. They have created a panoply of products that are supposed to make you loose weight, put on muscle and live longer disease-free lives without any change in behavior. And sales are good.

We are a tough species. Ten thousand generations of evolution have crafted humans that are remarkably effective at absorbing and using the essential nutrients from food. For better or worse, this machinery is programed to work on food, not pills or powders. The "housing" of these nutrients in food seems to be an important part of their utility.

Evolution has also wired us for lots of movement. We have inadvertently conducted a national experiment on the consequences of sedentary behavior and the consumption of huge caloric loads of processed foods. The results are in: an epidemic of obesity, diabetes, hypertension and cardiovascular disease.

It would seem that the Inuit's historical lack of cancer was more than a fish story. But we like simple stories that provide simple solutions and that don't ask us to change. If we can appreciate the benefits of whole foods, we should be able to understand the need for thinking about whole people.

Surely many variables determined the Inuit's remarkable health, including lots of physical activity, clean air and water, a close community of supportive social connections, a relatively homogenous population with similar genetics, and yes, their diet, too.

Anyone who has a pill to cure the man-made epidemics of our time smells a little fishy to me.

For more by Paul Spector, M.D., click here.

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