Something is Fishy about Omega 3’s causing aggressive Prostate Cancer

I heard about this this study from a news wire late yesterday evening and already received about a dozen emails from patients, friends and colleagues on the latest news suggesting that omega-3 fatty acids increases the risk of prostate cancer – including aggressive prostate cancer.

HERE is the link to the abstract of the study

Details of the study:

• Brasky et al. looked at collected data and specimens from the SELECT trial which showed in a study that those men who consumed synthetic form of vitamin E had a 17% chance of developing prostate cancer – More on the SELECT trial and synthetic vitamin E HERE

• The findings indicate that high concentrations of EPA, DPA and DHA — the three anti-inflammatory and metabolically related fatty acids derived from fatty fish and fish-oil supplements — are associated with a 71 percent increased risk of high-grade prostate cancer.

• The study also found a 44 percent increase in the risk of low-grade prostate cancer and an overall 43 percent increase in risk for all prostate cancers. (Brasky et al. 2013)

• What’s even more interesting is that Omega 6 fatty acids were associated with lower risks of total prostate cancer(Brasky et al. 2013)

Interestingly, this same study group published a paper in 2011 showing Docosahexaenoic acid (DHA) was positively associated with high-grade prostate cancer but trans-fatty acids found in participants blood showed a DECREASE risk of aggressive prostate cancer.(Brasky et al. 2011)

That’s right, the same trans fatty acids from margarine and cooked oils that contribute to heart disease. Yes, the same type of fat that is banned from New York restaurants.

Omega 6 fatty acids has shown to have an adverse effect if taken in excess and has been implicated in the development of several cancers including prostate (Berquin et al. 2007). Omega 6 fatty acids (namely arachidonic acid) is converted by CycloOxygenase -2 enzyme into prostaglandin E2, a pro-inflammatory molecule implicated in the development of numerous cancers (Wang et al. 2007)
Imbalanced Omega 6: Omega 3 ratios (higher Omega 6) have shown to increase the risk of prostate cancer (Leitzmann et al. 2004)

Take home message from both Brasky studies: Eat more trans fatty and omega – 6 fatty acids and men will prevent aggressive prostate cancer.  I don’t know about this. This smell too…well,  fishy.

My take on this (thus far)

One must be very careful with making decisions based on the latest news bytes and headlines. We, as a society, have a tendency to make decisions based on the last study or news advertised, rather than the combination of studies published on a specific topic.

The last study is not necessarily the best study.

In addition, studies should be read critically – there are inherent flaws in most of them.

The findings from Brasky et al. 2013 seem to be a retrospective study (looking back in time) and does NOT show cause and effect.

Studies that are prospective in design rank higher in importance of evidence and are more useful and suggestive in our decision making on what to consume to improve our health.

Are there prospective studies showing protective benefits of omega 3 fatty acids against prostate cancer?

Yup.

Researchers investigated the effect of dietary fish intake amongst 6272 Swedish men who were followed-up for 30 years. That study reported that men who ate no fish had a two–three-fold increase in the risk of developing prostate cancer compared with those who consumed large amounts of fish in their diet. (Terry et al. 2001)
Another prospective cohort study based on the Physician’s Health Study found that fish consumption (≥5 times per week) was not related to prostate cancer risk but was protective of prostate cancer–specific death.(Chavarro et al. 2008)
Other studies have suggested lower prostate cancer risk with Omega 3 fatty acids from fish in Swedish men (Norrish AE, et al.) and in Japanese and Brazilian men (Kobayashi et al. 1999).

A large prospective cohort established in 1986 looked at 51,529 American men, 40 – 75 years of age, completed a mailed questionnaire about demographic and medical information found that a high intake of fish was associated with a lower risk of metastatic prostate cancer. A similar association was also found for dietary marine fatty acids from food.

An important clinical study published by a group at the Harvard School of Public Health examined the link between dietary fish consumption and the risk of metastatic prostate cancer. This paper reported results from the Health Professionals Follow-up Study that involved 47,882 men over twelve years. During the twelve years, 2,483 cases of prostate cancer were identified. Of these, 617 were advanced and 278 were metastatic. Eating fish more than three times a week reduced the risk of prostate cancer but had an even greater impact on the risk of metastatic prostate cancer. For each additional 500 mg of marine fat consumed, the risk of metastatic disease decreased by 24%! (Augustsson, et al. 2003).

In a meta-analysis (a study of studies) Szymanski and his team found that a significant 63% reduction in prostate cancer-specific mortality in those that consumed fish but no link between eating lots of fish and men’s risk of developing prostate cancer. (Szymanski et al. 2010).

Am I getting carried away with all these citations yet?

I know the content became scientifically heavy but I just wanted to make a point that there are reason’s why many practitioners like myself recommend fish and fish oils to patients.

Final note and Doggy Bag

Most men will develop prostate cancer within time regardless of what they eat or don’t eat. If you live long enough, you’ll get it. The deadly kind is what we are trying to avoid.

The 71% aggressive prostate cancer associated with Omega 3 fatty acid consumption sounds dubious.

The fish oils from fish or supplements in the study did not control for the quality of fish or fish oil. Some fish (and fish oil supplements) can contain environmental chemicals that can contribute to prostate cancer such as PCB (Ritche et al. 2005). Also, fish oils can oxidize easily if not careful which may make them more damaging. This was not accounted for in this study.

Personally, I am not ready to ignore the plethora of research suggesting its beneficial effects.

I just popped 3 fish oils a minute ago. I am not making any personal changes on my fish oil consumption based on a blood test of Omega 3 fatty acids from a retrospective study. In my opinion, this study is informative, mildly suggestive, but weak.

I do recommend for readers to be properly monitored by a nutritionally oriented physician when making dietary choices. There are individual nuances where, indeed, a nutrient can potentially make health matters worse.

Lastly, (whew!) another shortcoming of both Brasky studies is that we do not know the diet of the studied subjects.

The consumption of fish or fish oil supplements with crappy food does not make the crappy food less crappy. Another words, a poor diet with fish or fish oils will not protect men from prostate cancer.

This is a hot topic, so chime in if you’d like.

References:

Berquin IM, Min Y, Wu R et al. Modulation of prostate cancer genetic risk by omega-3 and omega-6 fatty acids. J Clin Invest 2007; 117: 1866–75
Wang MT, Honn KV, Nie D. Cyclooxygenases, prostanoids, and tumor progression. Cancer Metastasis Rev 2007; 26: 525–34

Terry P, Lichtenstein P, Feychting M, Ahlbom A, Wolk A. Fatty fish consumption and risk of prostate cancer. Lancet 2001; 357: 1764–6

Chavarro JE et al. A 22-y prospective study of fish intake in relation to prostate cancer incidence and mortality. Am J Clin Nutr 2008; 88: 1297–303.

Augustsson, K., et al., A prospective study of intake of fish and marine fatty acids and prostate cancer. Cancer Epidemiol Biomarkers Prev, 12(1): p. 64-7, 2003.

Szymanski KM, Wheeler DC, Mucci LA. Fish consumption and prostate cancer risk: a review and meta-analysis. Am J Clin Nutr. 2010 Nov;92(5):1223-33.

Leitzmann MF, Stampfer MJ, Michaud DS, et al. Dietary intake of n-3 and n-6 fatty acids and the risk of prostate cancer. Am J Clin Nutr. 2004 Jul;80(1):204-16.

Ritchie JM, Vial SL, Fuortes LJ, Robertson LW, Guo H, Reedy VE, Smith EM.Comparison of proposed frameworks for grouping polychlorinated biphenyl congener data applied to a case-control pilot study of prostate cancer. Environ Res. 2005 May;98(1):104-13.