Apparent benefit tied to fish fats’ impact on a key pro-inflammatory factor; Fats' effects seen as stronger in certain genetic variants
by Craig Weatherby
What's a guy supposed to do?
Two recent studies found that screening tests for PSA, or prostate specific antigen, are good at discovering prostate cancer, and can save lives... especially for men with aggressive forms of the disease.
But the same studies found that PSA tests often raise false alarms, which can lead to needless treatment and resulting impotence or incontinence (Andriole GL et al 2009; Schröder FH et al. 2009).
This does not mean men should avoid getting a PSA test and/or rectal exam, since ignorance can be deadly. At the very least, men should discuss the testing options with their physician.
The PSA dilemma only increases the importance to men of ensuring they are doing all they can to deter the disease through lifestyle choices, including maintaining a healthy weight.
New study supports omega-3s for prostate health
Omega-3s from fish may help deter prostate cancer, according to a new report out of the University of California-San Francisco.
A team led by professor John S. Witte, Ph.D., conducted a “case-control” study, in which they compared the diets of 466 men diagnosed with aggressive prostate cancer to the diets of 478 healthy men (Fradet V et al. 2009).
They classified the men according to their estimated omega-3 intake, and found that the men who consumed the most omega-3s from fish or fish oil were 63 percent less likely to have aggressive prostate cancer, compared to men with the lowest omega-3 intake.
The researchers then examined the effect of omega-3s in men with a genetic variant of the pro-inflammatory COX-2 enzyme, which causes it to drive inflammation even more powerfully.
(Prescription pain relievers such as Vioxx and Celebrex are called COX-2 inhibitors, because they reduce inflammation and pain by blocking that enzyme. However, unlike omega-3s, turmeric, and other natural COX-2 inhibitors, these potent synthetic drugs produce worrisome side effects.)
Men with low omega-3 intakes and this virulent gene variant were more than five times more likely to have advanced prostate cancer.
In contrast, men with high omega-3 intakes had a substantially reduced risk, even if they carried the risky COX-2 gene variant.
As Witte said in a press release, “The COX-2 increased risk of disease was essentially reversed by increasing omega-3 fatty acid intake by a half a gram [500 mg] per day.”
And he made a telling analogy: “If you want to think of the overall inverse association in terms of fish… the strongest effect was seen from eating dark fish such as salmon one or more times per week” (AACR 2009).
This study supports indications from several other epidemiological studies suggesting that omega-3s may discourage prostate cancer growth, especially in the presence of the riskiest COX-2 gene variants (Hedelin M et al. 2007).
Eric Jacobs of the American Cancer Society, says the jury is still out on connecting omega-3s with a reduced risk of advanced prostate cancer: “In this study, a diet high in long-chain omega-3 fatty acids was associated with lower risk of developing advanced prostate cancer… [but] some previous studies did not find similar results.”
He called for more research into omega-3s’ role in prostate cancer prevention, and added that many studies have shown that obesity is associated with increased risk of developing advanced prostate cancer.
For more on this topic, search our newsletter archive for “prostate”.
- American Association for Cancer Research (AACR). Omega-3 Fatty Acids Reduce Risk of Advanced Prostate Cancer. March 24, 2009. Accessed online at http://www.aacr.org/home/public--media/aacr-press-releases.aspx?d=1267
- Andriole GL, Grubb RL 3rd, Buys SS, Chia D, Church TR, Fouad MN, Gelmann EP, Kvale PA, Reding DJ, Weissfeld JL, Yokochi LA, Crawford ED, O'Brien B, Clapp JD, Rathmell JM, Riley TL, Hayes RB, Kramer BS, Izmirlian G, Miller AB, Pinsky PF, Prorok PC, Gohagan JK, Berg CD; PLCO Project Team. Mortality results from a randomized prostate-cancer screening trial. N Engl J Med. 2009 Mar 26;360(13):1310-9. Epub 2009 Mar 18.
- Fradet V, Cheng I, Casey G, Witte JS. Dietary Omega-3 Fatty Acids, Cyclooxygenase-2 Genetic Variation, and Aggressive Prostate Cancer Risk. Clin Cancer Res. 2009 Mar 24. [Epub ahead of print]
- Hedelin M, Chang ET, Wiklund F, Bellocco R, Klint A, Adolfsson J, Shahedi K, Xu J, Adami HO, Grönberg H, Bälter KA. Association of frequent consumption of fatty fish with prostate cancer risk is modified by COX-2 polymorphism. Int J Cancer. 2007 Jan 15;120(2):398-405.
- Reinberg S. Omega-3 Fatty Acids Guard Against Advanced Prostate Cancer. HealthDay News, March 24, 2009. Accessed at http://health.usnews.com/articles/health/healthday/2009/03/24/omega-3-fatty-acids-guard-against-advanced.html
- Schröder FH, Hugosson J, Roobol MJ, Tammela TL, Ciatto S, Nelen V, Kwiatkowski M, Lujan M, Lilja H, Zappa M, Denis LJ, Recker F, Berenguer A, Määttänen L, Bangma CH, Aus G, Villers A, Rebillard X, van der Kwast T, Blijenberg BG, Moss SM, de Koning HJ, Auvinen A; ERSPC Investigators. Screening and prostate-cancer mortality in a randomized European study. N Engl J Med. 2009 Mar 26;360(13):1320-8. Epub 2009 Mar 18.