Omega-3s in the blood may boost risk of aggressive prostate cancer

http://www.eurekalert.org/pub_releases/2011-04/fhcr-hpo042511.php

by cwan • 15 years ago

13 8 15 years ago

Analyzing data from a nationwide study involving more than 3,400 men, researchers at Fred Hutchinson Cancer Research Center found that men with the highest blood percentages of docosahexaenoic acid, or DHA, an inflammation-lowering omega-3 fatty acid commonly found in fatty fish, have two-and-a-half-times the risk of developing aggressive, high-grade prostate cancer compared to men with the lowest DHA levels.

Correlation isn't causation. There are literally a billion possible factors that could be responsible besides a direct relationship. Of course, the same applies to any research demonstrating the efficacy of Omega-3s, too.

This is the problem with a lot of nutrition studies: a huge number of completely false associations were and still are being invented because of an inability to control for important factors. For example, the "fiber theory" of health has turned out to be almost completely false: it appeared to be "healthy" because eating fiber meant eating fewer (digested) carbohydrates. The fiber itself did almost nothing for health.

It gets worse when massive chains of correlations are assumed to be causes. A is correlated with B, B is correlated with C, C is correlated with D, therefore A causes D. The whole mess of saturated fats, cholesterol levels, heart attacks, and heart disease is a case of this.

aksbhat• 15 years ago

link to the paper: http://aje.oxfordjournals.org/content/early/2011/04/19/aje.k...

I guess that a paper won't get accepted in Am. J. Epidemiol without proper consideration of such correlation.

The studies generally try to control for homophilly, contagion and confounding etc.

gfunk911• 15 years ago

Discussion of this study

http://www.marksdailyapple.com/fish-oil-prostate-cancer/

georgieporgie• 15 years ago

That was a really interesting analysis.

"To top that off, this study derails the otherwise consistent train of research showing that DHA seems protective at best (and neutral at worst) when it comes to prostate health. In 2001, a study of over 6,000 Swedish men found that the folks eating the most fish had drastically lower rates of prostate cancer than those eating the least. Another study from New Zealand found that men with the highest DHA markers slashed their prostate cancer risk by 38% compared to the men with the lowest DHA levels. And yet another study tracking Japanese men in Japan and Brazil found that omega-3 levels in the blood were consistently linked with a reduction in prostate cancer."

(I'll keep taking my fish oil supplements until I hear something much more concrete)

robchez• 15 years ago

I hate how much play study's like this get in the media. Anyway, some links discussing it:

http://high-fat-nutrition.blogspot.com/2011/04/prostate-canc...

http://perfecthealthdiet.com/?p=3309

http://www.marksdailyapple.com/fish-oil-prostate-cancer/

tokenadult• 15 years ago

Good advice from the submitted article: "'Overall, the beneficial effects of eating fish to prevent heart disease outweigh any harm related to prostate cancer risk,' Brasky said. 'What this study shows is the complexity of nutrition and its impact on disease risk, and that we should study such associations rigorously rather than make assumptions,' Brasky said."

There is a lot of scholarly literature on the general issue,

http://scholar.google.com/scholar?q=docosahexaenoic+acid+pro...

and it will be interesting to see how the trade-offs are resolved.

CoffeeDregs• 15 years ago

[The following assumes there is a causal relationship...]

As a reader of Mark's Daily Apple and a follower of a Paleo diet, this study surprised me. Yes, the study can be argued against, but I have a more fundamental issue: "optimizing" your diet may be impossible. The needs of the human body and the composition of nutrients/macro-nutrients in food are both wildly varying and neither was "designed", so it's possible that strategies which keep you in great health in young/middle-age will produce ill-health later on. There's little evolutionary pressure exerted by grandparents on grandkids and prostate cancer is usually a very slow growing, late stage disease, so it shouldn't be inconceivable that a young/middle-age favoring diet harms late-stagers.

That said, prostate cancer (which my father had) has a very high survival rate, so I'd happily trade a litany of conditions potentially caused by a "non-good" diet for prostate cancer caused by a "good" diet.

jessriedel• 15 years ago

In numbers: there are about 300k male deaths per year from heart disease in the US, but about 30k from prostate cancer;

Omega-3s in the blood may boost risk of aggressive prostate cancer

Related Stories