A Closer Look at Fish Oil and Prostate Cancer – Part 3

In two previous blog posts I reviewed the current
controversy about the study by Thomas Brasky and colleagues, who found that men
with high-grade prostate cancer had slightly higher levels of the fish-based
omega-3s, EPA and DHA.  As I noted, this
is a study with many flaws and limitations, which restricts its
credibility.  In addition, I’ve detailed
other variables that may explain the study’s findings – cooking the fish at
very high temperatures, which can generate mutagenic compounds, the tendency of
both DHA and EPA to get oxidized (go rancid), and the potential that the
fish/fish oil had mercury contamination. 

So, what can men concerned about preventing prostate cancer
do based on the results of these studies? And what do these studies say to men who already have prostate cancer?

First, let’s review why it’s important to include fish and
fish oil in the diet.  In the real world,
people aren’t concerned about preventing one disease at a time.  We’re concerned about preventing all diseases
– heart disease, diabetes, cancer, dementia and many others.  While family history may motivate individuals
to take special steps against one disease, they still need to be cognizant of
the other health risks associated with diet. 
Recent studies and reviews indicate that fish consumption or fish oil
may contribute to the prevention of colorectal cancer (and breast cancer),
Alzheimer’s disease, asthma, stroke and coronary heart disease.  People may also increase fish consumption or
take fish oil to manage various health conditions, including diabetics who have
had heart attacks, people with macular degeneration, those with heart failure,
men with elevated C-reactive protein, kidney dialysis patients and those with
elevated triglycerides.  I would note
that in all these cases it is the entire diet that is important: if you eat a
lot of fish, or take fish oil supplements, but still have a diet that is high
in vegetable oils that contain omega-6s, trans fats, refined flours and sugars,
or various kinds of junk foods, you are still putting yourself at risk of
several diseases.  In other words, there
is no supplement regimen out there that will compensate for a poor diet!

So there are many sound reasons for men to be taking fish
oil and eating fish.  But the problems
raised by Brasky’s study may still be of concern to some patients.  Can the possible concerns with fish
consumption raised by Brasky’s study and the other studies we mentioned be
alleviated?  Since there’s no test for
the particular gene analyzed by Catsburg’s team, it’s wise for men, as well as
women (who might be incurring genetic damage related to some other type of
cancer), to limit consumption of white fish that is grilled, pan-fried,
oven-broiled, barbequed or otherwise exposed directly to very high temperatures,
especially when this results in the fish being overdone.  Some of the same precautions that are
recommended for avoiding grilled meat can be applied to fish.  These include using lower-temperature cooking
methods, such as baking or poaching (a wonderful and easy way to cook fish –
see the recipe for Poached Peppercorn Salmon that follows this article).  You can also gently pre-cook fish before
putting it on the barbeque, so that it doesn’t need to be on the grill as long,
or remove charred portions of the fish before eating.  And don’t overcook fish – it should be cooked
until just done, for better taste and texture as well as safety.

You can reduce the risk of mercury pollution by limiting
intake of predator fish like swordfish, shark, mackerel, marlin, albacore,
yellowtail and orange roughy, and not eating canned tuna more than about once a
week. If you’re interested in prostate cancer prevention, you don’t have to
give these up entirely, and I would urge you, in fact, to continue including
them in your diet.  But I don’t suggest
eating two cans of tuna every day, as some people involved in body-building are
rumored to do!  High quality fish oil
supplements, obtained from deep cold water sources, do not contain
mercury. 

The problem with possible oxidation of fish oil, as well as,
to some extent, the free radicals generated when fish is grilled or barbequed,
can also be addressed through antioxidants. 
One of the crucial steps is to ensure that your diet contains sufficient
broad-spectrum antioxidants from vegetables and fruits.  At the Block Center, we do comprehensive
“terrain testing” on our patients, which, among many other things, enable our
dietitians to determine if someone’s dietary antioxidant intake is sufficient,
and how you can use better food choices and possibly supplementation to reach
optimal antioxidant capacity in your blood. 
Terrain testing will also tell you whether or not you have inflammatory
conditions that should be addressed by taking an anti-inflammatory supplement
such as fish oil or curcumin, and what dosage level would be needed and
suitable for you based on these laboratory findings.  Oxidized fish oil can be avoided by using a
high quality fish oil product, ideally one that’s undergone independent
testing.  Products that are molecularly
distilled increase the critical anti-inflammatory components, and if they are
processed under nitrogen rather than in open air, it is possible to avoid the
unnecessary and harmful oxidation that can occur routinely with many fish oils.  These procedures are used in the fish oils
recommended at the Block Center.  Our
Arctic Blox fish oil product is tested for mercury and other heavy metals, and
does not contain any such contaminants. 
It also has added tocopherols and rosemary extract that provides further
antioxidant protection to help keep the fish oil from going rancid. 

What about men who already have prostate cancer? 

Dr Brasky specifically noted that the data in his study do
not apply to men with prostate cancer. 
The finding that prostate cancer mortality is lower in men with high
fish intake, noted in the meta-analysis by Szymanski and colleagues, still
stands and was not contradicted by Brasky’s work or the other studies we have
mentioned.  In addition, a randomized
trial in which men with early prostate cancer either continued their customary
diet or switched to a comprehensive lifestyle intervention featuring a low-fat,
plant-based diet along with a soy supplement and, importantly, fish oil
supplementation, found that significantly fewer men had to undergo further
prostate cancer treatment in the lifestyle group than in those following their
usual diet.  This suggests that fish oil
as part of a full integrative program is helpful, not harmful, for prostate
cancer patients.  Another study
randomized prostate cancer patients to eat either a Western-type diet or a
low-fat diet supplemented with 5 grams daily of fish oil.  This diet was eaten for only about a month,
between the patients’ initial biopsies and prostate removal surgeries.  The fish oil group had a 32% reduction in
Ki-67, an index of prostate cancer cell proliferation.  When serum from these patients was applied to
prostate cancer cells in the lab, serum from fish oil patients significantly
reduced the cancer cell growth, whereas serum from the Western diet patients
slightly increased it.  We have observed
similarly positive results with our integrative program at the Block Center,
which regularly includes fish intake and fish oil supplements, even with
advanced prostate cancer patients.  Since
actual randomized trials are finding beneficial results with fish oil
supplementation for prostate cancer patients, we do not see any concern for
prostate cancer patients taking fish oil. 
In fact, I recommend and encourage it as part of a comprehensive diet
and lifestyle intervention, along with terrain testing, in order to determine
appropriate dosages of fish oil and antioxidants, as well as gauging other
nutritional needs.

The bottom line is that Brasky’s study is interesting, but certainly
not alarming, when viewed in the full context of the research in this area, and
when one takes a closer look at the study’s methodology.  The results of Catsburg’s related work on
overcooked and fried fish, and the need for all of us to make sure that we use
high quality supplements and maintain adequate antioxidant intake in our diets
can serve as good reminders to stick with our integrative dietary goals.  Remember that cancer, and health in general,
is not about one single lab test, one single food or one single
supplement.  It’s about all that you do
to take care of your health.  This is a
good opportunity to review what you’re doing with your diet and supplements, to
consider terrain testing if you’re concerned, and to remind yourself that it is
not a good idea for any of us to become overly upset or anxious over the
results of a single scientific study.