47 replies to this topic

[brundall]

Any thoughts? http://www.dailymail...-cancer-70.html

[joelcairo]

"There is not really a single example of where taking a supplement lowers chronic disease risk."

Well this is horse manure. Really makes me wonder about any study that he was involved in.

I was looking for the published study corresponding to the Daily Mail article, and I found this 2013 study: The top third of consumers of omega-3 fatty acids only had 62% the incidence of pancreatic cancer as compared to the bottom third.
http://aje.oxfordjou...177/2/152.short

And this 2012 study, suggesting that high consumers of DHA and EPA had only 57% and 64%, respectively, risk of ovarian cancer:
http://link.springer...2-0436-z#page-1

And this one from 2011: "Intake of eicosapentaenoic and docosahexaenoic acids were inversely associated with [breast cacner] risk."
http://www.tandfonli...33#.Ud4UFWcr7Nt

Seems like the jury is not yet in.

[Luddist]

Here's the abstract: http://jnci.oxfordjo...djt174.abstract

This is a better news article: http://health.usnews...risk-study-says

They measured blood lipids while doing a study on selenium and vitamin E related to prostate cancer. It's not specifically pointing at fish oil supplements as a cause for higher prostate cancer. I wonder if maybe toxic contaminants in larger fish in the study participants' diets could be influencing the results. Fish-accumulated toxins would reasonably be proportional to blood omega 3 levels.

A study specifically isolating fish oil supplements vs. dietary fish vs. neither and cancer risk would be good to see.

Edited by Luddist, 11 July 2013 - 03:07 AM.

[ta5]

The study was not on fish oil, omega 3 intake, or fish intake.

Here is a another recent meta-analysis that found a possible increased risk of aggressive prostate cancer risk. Again, this is also looking at serum levels, not intake. It's interesting that 5-ar inhibitors have the same type of risk profile: lower risk overall, but increased risk of high-grade cancer.




Can Urol Assoc J. 2013 May;7(5-6):E333-43.

The relevance of serum levels of long chain omega-3 polyunsaturated fatty acids and prostate cancer risk: A meta-analysis.

Chua ME, Sio MC, Sorongon MC, Morales ML Jr.
Institute of Urology and Research and Biotechnology Division, St. Luke's Medical Center, Philippines;

Our objective was to systematically analyze the evidence for an association between serum level long chain omega-3 polyunsaturated fatty acid (n-3 PUFA) and prostate cancer risk from human epidemiological studies. STUDY PROCEDURES: We searched biomedical literature databases up to November 2011 and included epidemiological studies with description of long chain n-3 PUFA and incidence of prostate cancer in humans. Critical appraisal was done by two independent reviewers. Data were pooled using the general variance-based method with random-effects model; effect estimates were expressed as risk ratio with 95% confidence interval (CI). Heterogeneity was assessed by Chi(2) and quantified by I(2), publication bias was also determined.

RESULTS:
In total, 12 studies were included. Significant negative association was noted between high serum level of n-3 PUFA doc-osapentaenoic acid (DPA) and total prostate cancer risk (RR:0.756; 95% CI 0.599, 0.955; p = 0.019). Likewise, a positive association between high blood level of fish oil contents, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and high-grade prostate tumour incidence (RR:1.381; 95% CI 1.050, 1.817; p = 0.021) was noted; however, this finding was evident only after adjustment was done on interstudy variability through the removal of a lower quality study from the pool.

CONCLUSIONS:
High serum levels of long chain n-3 PUFA DPA is associated with reduced total prostate cancer risk. While high blood level of EPA and DHA is possibly associated with increased high-grade prostate tumour risk.
PMID: 23766835

Edited by ta5, 11 July 2013 - 03:24 AM.

[smithx]

What do y'all make of this one? The paper isn't out yet (tomorrow?) but here's the press release:

Study confirms link between high blood levels of omega-3 fatty acids and increased risk of aggressive prostate cancer

Consumption of fatty fish and fish-oil supplements linked to 71 percent higher risk

http://www.fhcrc.org/en/news/releases/2013/07/omega-three-fatty-acids-risk-prostate-cancer.html

[smithx]

This is the author's press release:

http://www.fhcrc.org...ate-cancer.html

[Robot]

I can't tell from the abstract if they had made certain that the subjects with confirmed prostate cancer had started supplementation before diagnosis. This is a rather critical piece of information, because just taking blood serum levels of positively diagnosed subjects does not infer any direction of causality. It is highly likely that people with prostate cancer diagnosis would then start taking multivitamins, omega3 supplements and eat more fish (less meat). Does anyone have access to the actual paper?

[8bitmore]

I can't tell from the abstract if they had made certain that the subjects with confirmed prostate cancer had started supplementation before diagnosis. This is a rather critical piece of information, because just taking blood serum levels of positively diagnosed subjects does not infer any direction of causality. It is highly likely that people with prostate cancer diagnosis would then start taking multivitamins, omega3 supplements and eat more fish (less meat). Does anyone have access to the actual paper?

Yeah agreed; full paper here would be really good. I really dislike this sort of fearmongering and would love to look closer at how conclusion was reached (we have seen absolutely awful (i.e. hand-picked sources by authors to reach certain conclusion) meta-studies done on supplements before)

[niner]

Well, "It doesn't prove causality", as they say in cases like this, but dang, that sucks. That's another paper to add to my collection of "high dose fish oil dangers" links, which already included their earlier paper. So, let's see, what's more likely to kill me, CVD or pCa? Given my history, I'd probably have to say pCa, but it's kind of a tough call. How much fish oil is ok? They say:

The difference in blood concentrations of omega-3 fatty acids between the lowest and highest risk groups was about 2.5 percentage points (3.2 percent vs. 5.7 percent), which is somewhat larger than the effect of eating salmon twice a week, Kristal said.

Nutritiondata.com says a 154g serving of Atlantic wild salmon, cooked (dry heat) is 3982mg total omega 3. Thus the "high risk" group is 8g total w3 a week. That's less than I supplement at the moment, but not that much less.

[kjh]

Would love more clarity on this too. This really shook me. Because to me, fish oil is probably the most benign of the stuff I take.

[joelcairo]

These are all studies of fish oil with respect to prostate cancer specifically. On balance I'd say there was a trend to a beneficial effect or perhaps no effect.

It may be significant that some studies look at absolute levels of consumption or serum levels, and others look at the omega-3/omega-6 ratio.


A high ratio of dietary n-6/n-3 polyunsaturated fatty acids is associated with increased risk of prostate cancer [2011]
http://www.sciencedi...271531711000030

"Our results showed no significant associations between specific n-3 or n-6 PUFA intakes and prostate cancer risk."

"The highest dietary ratio of n-6/n-3 was significantly associated with elevated risk of high-grade (OR, 3.55), but not low-grade prostate cancer (OR, 0.95)."



Dietary Omega-3 Fatty Acids, Cyclooxygenase-2 Genetic Variation, and Aggressive Prostate Cancer Risk [2009]
http://clincancerres...15/7/2559.short

"Increasing intake of LC n-3 [long-chain omega-3 fatty acids] was strongly associated with a decreased risk of aggressive prostate cancer. The OR for prostate cancer comparing the highest with the lowest quartile of n-3 intake was of 0.37."



Fatty fish consumption and risk of prostate cancer [2001]
http://www.sciencedi...140673600048893

"During 30 years of follow-up, men who ate no fish had a two-fold to three-fold higher frequency of prostate cancer than those who ate moderate or high amounts did."



Effects of Omega-3 Fatty Acids on Cancer RiskA Systematic Review [2006]
http://jama.jamanetw...rticleid=202260

"Among the 4 [prostate cancer] studies that assessed risk relative to fish consumption, 1 demonstrated a favorable effect (risk for never/seldom consumption relative to moderate consumption [RR, 2.3]), 1 showed a trend toward a favorable effect, and 2 did not find an association."

"No significant association with the incidence of prostate cancer was found with marine omega-3 fats, EPA, or DHA consumption."

[Luddist]

I can't tell from the abstract if they had made certain that the subjects with confirmed prostate cancer had started supplementation before diagnosis. This is a rather critical piece of information, because just taking blood serum levels of positively diagnosed subjects does not infer any direction of causality. It is highly likely that people with prostate cancer diagnosis would then start taking multivitamins, omega3 supplements and eat more fish (less meat). Does anyone have access to the actual paper?

Yeah agreed; full paper here would be really good. I really dislike this sort of fearmongering and would love to look closer at how conclusion was reached (we have seen absolutely awful (i.e. hand-picked sources by authors to reach certain conclusion) meta-studies done on supplements before)

I'm not saying he definitely has one, but this quote: “We’ve shown once again that use of nutritional supplements may be harmful,” by Alan Kristal, Dr.P.H. sounds like he could be showing a bias to me. Then again, given that he's done research on this before with similar results, it's a factual statement.

Browsing the organization's press releases, it's bothersome to me that when they refer to vitamin E as being potentially harmful, they don't specifically say they're talking about the dl-alpha tocopherol acetate form as used in the "SELECT" study. There's evidence that a proper balance of vitamin E tocopherols and tocotrienols, light on the alpha tocopherol variety, has positive effects. Overgeneralizing is not a good thing for science.

Edited by Luddist, 11 July 2013 - 06:38 PM.

[motorcitykid]

Maybe fish oil is the smoking gun? What type of fish oil was used in the study. Most fish oil supplements contain some sort of ingredient to help preserve the oil. Nordic Naturals contain D-alpha tocopherol and rosemary extract. LEF contains olive leaf extract. Maybe these added ingredients used to preserve the fish oil have something to do with the prostate cancer phenomenon.

[niner]

joelcairo, thanks for doing the legwork on that and putting this latest paper/media frenzy into some context. I think the most important of those might be the third ref:

The Lancet Volume 357, Issue 9270, 2 June 2001, Pages 1764–1766
Fatty fish consumption and risk of prostate cancer

Paul Terry, Paul Lichtenstein, Maria Feychting, Anders Ahlbom, Alicja Wolk
Karolinska Institutet, Stockholm, Sweden
http://dx.doi.org/10...6/S0140-6736(00)04889-3

Consumption of fatty fish might reduce the risk of prostate cancer, although epidemiological studies of fish consumption are rare. We studied the association between fish consumption and prostate cancer in a population-based prospective cohort of 6272 Swedish men. During 30 years of follow-up, men who ate no fish had a two-fold to three-fold higher frequency of prostate cancer than those who ate moderate or high amounts did. Our results suggest that fish consumption could be associated with decreased risk of prostate cancer.

I like this study because it is large and is prospective. I'd like to hear what the Fred Hutchinson guys have to say about the existing literature. Were they just grandstanding to get their names on TV?

[Robot]

Common sense also points to a non-detrimental effect when you look at the shockingly and unusually low prostate cancer rate in Eskimo cultures, where they consume a very large amount of fish (and thus omega3 oils). You could say these Inuit cultures have a genetic protection, but then this coincidence seems to occur too frequently in other high fish consuming countries, like Japan, Greece and Sweden too.

[nameless]

Playing Devil's advocate, it isn't unreasonable to assume too much fish oil can suppress one's immune system. Killer cell studies showed it only required a rather small amount of EPA to do this (720mg-ish, if I recall right). I have never been sure if this is immune system modulation rather than true suppression though.

It'd be nice to figure out what dose the high Omega 3 group in the study would be equivalent to. There is also the possibility that fish is fine, but supplements were causing a problem ... if they didn't have E in them, they could have suppressed serum E in the participants, for instance.

[babcock]

I fully believe in the benefit of omega-3's but I'm not sure how bioavailable they are in pill form. I try to eat a lot of salmon and other fish in my regular diet in order to get the omega-3's.

Here's a few studies:

Omega-3 Fatty Acid Supplementation Not Associated With Lower Risk of Major Cardiovascular Disease Events

Omega 3 fatty acid for the prevention of cognitive decline and dementia

[niner]

I fully believe in the benefit of omega-3's but I'm not sure how bioavailable they are in pill form. I try to eat a lot of salmon and other fish in my regular diet in order to get the omega-3's.

Here's a few studies:

Omega-3 Fatty Acid Supplementation Not Associated With Lower Risk of Major Cardiovascular Disease Events

Omega 3 fatty acid for the prevention of cognitive decline and dementia

Both of these studies find no benefit from fish oil; the first for CVD, and the second for dementia. I don't think the problem is bioavailability- but something isn't working here. I do think that excessive amounts of fish oil can be harmful.

[babcock]

I fully believe in the benefit of omega-3's but I'm not sure how bioavailable they are in pill form. I try to eat a lot of salmon and other fish in my regular diet in order to get the omega-3's.

Here's a few studies:

Omega-3 Fatty Acid Supplementation Not Associated With Lower Risk of Major Cardiovascular Disease Events

Omega 3 fatty acid for the prevention of cognitive decline and dementia

Both of these studies find no benefit from fish oil; the first for CVD, and the second for dementia. I don't think the problem is bioavailability- but something isn't working here. I do think that excessive amounts of fish oil can be harmful.

Yea, that was what I was getting at. First study is regarding supplementation directly.

[Hebbeh]

Playing Devil's advocate, it isn't unreasonable to assume too much fish oil can suppress one's immune system. Killer cell studies showed it only required a rather small amount of EPA to do this (720mg-ish, if I recall right). I have never been sure if this is immune system modulation rather than true suppression though.

It'd be nice to figure out what dose the high Omega 3 group in the study would be equivalent to. There is also the possibility that fish is fine, but supplements were causing a problem ... if they didn't have E in them, they could have suppressed serum E in the participants, for instance.

I don't buy the immune suppression theory. I'm 56 years old. Been using fish oil going on 15 years. I currently take 4 grams/day but I've taken more before...much more. At one time I was taking 18 grams/day...for a year. Anyway, I don't get sick. Not even when all the people around me are sick. I might have had a cold 4 or 5 years ago. Fish oil hasn't had any negative effect on my immune system.

I believe that a lot of unhealthy people take fish oil and other supplements (after the fact) after an unhealthy lifestyle in the hopes of curing their ills. To little to late. And then the studies link the supplements (fish oil in this case) to the pre-existing health conditions....it couldn't of been the unhealthy lifestyle and pre-existing conditions....it had to be the fish oil they popped after the fact that killed them.

Edited by Hebbeh, 12 July 2013 - 04:21 AM.

[nameless]

I don't buy the immune suppression theory. I'm 56 years old. Been using fish oil going on 15 years. I currently take 4 grams/day but I've taken more before...much more. At one time I was taking 18 grams/day...for a year. Anyway, I don't get sick. Not even when all the people around me are sick. I might have had a cold 4 or 5 years ago. Fish oil hasn't had any negative effect on my immune system.

I believe that a lot of unhealthy people take fish oil and other supplements (after the fact) after an unhealthy lifestyle in the hopes of curing their ills. To little to late. And then the studies link the supplements (fish oil in this case) to the pre-existing health conditions....it couldn't of been the unhealthy lifestyle and pre-existing conditions....it had to be the fish oil they popped after the fact that killed them.

N = 1 is a real dangerous way to look at any supplement (or med). It also doesn't really apply to this particular prostate cancer risk study either. Perhaps you have a great immune system, better than most people. Perhaps you have great genetics ... or are taking other supplements that help. Or are just lucky.

I was referring to killer cell studies like this one:
Dietary supplementation with eicosapentaenoic acid, but not with other long-chain n-3 or n-6 polyunsaturated fatty acids, decreases natural killer cell activity in healthy subjects aged >55 y.
http://www.ncbi.nlm....pubmed/11237929

I am not saying it plays a role in the prostate cancer study, nor can say it's 100% accurate either ... but too much fish oil has shown to cause issues like this. Too much fish oil without E can also cause low serum E. It would be interesting to know what participants received Omega 3s from diet vs fish oil, but I don't think they can figure that out (study wasn't looking at fish oil intake originally). It is possible that the unhealthiest people in this study took extra fish oil in the belief it would help them. I would think (or hope) those who ran the study would have taken that into account, however -- if everyone with high Omega 3 serum levels in this study also smoked, were heavy drinkers, etc, I think it would be an obvious red flag.

Edited by nameless, 12 July 2013 - 06:55 AM.

[kakker]

I just saw this yesterday. A quick pubmed search led to another recent study that apparently reached different conclusions.

http://www.ncbi.nlm....pubmed/23613715

http://www.ncbi.nlm....les/PMC3629172/

Edited by kakker, 12 July 2013 - 02:02 PM.

[kakker]

A recent meta-analysis:

http://www.ncbi.nlm....pubmed/23766835

[nameless]

I just saw this yesterday. A quick pubmed search led to another recent study that apparently reached different conclusions.

http://www.ncbi.nlm....pubmed/23613715

http://www.ncbi.nlm....les/PMC3629172/

Interesting ... it could very well be how the fish is prepared that makes the difference. Salted/Smoked (or I would add blackened) fish would make some sense.

I had also considered the difference between fish oils and actual fish, and was wondering if the fact that fish oil tends to be predominantly EPA, while real fish is usually higher in DHA, could play a role. But I believe one previous prostate study showed an increase in risk from high DHA, so fish oil wouldn't be the culprit in that case, or at least not based on EPA/DHA ratios.

Maybe it's as simple as the way the fish is cooked, which is sort of similar to the flax seed + prostate scare ... ALA from meat vs other forms.

Edited by nameless, 12 July 2013 - 06:17 PM.

[Hebbeh]

It is possible that the unhealthiest people in this study took extra fish oil in the belief it would help them. I would think (or hope) those who ran the study would have taken that into account, however -- if everyone with high Omega 3 serum levels in this study also smoked, were heavy drinkers, etc, I think it would be an obvious red flag.

Apparently not....it was apparently intentionally omitted to influence the preconceived outcome of the study which was performed by an assistant professor apparently for the publicity.

http://www.michaelsa...michael-savage/

Edited by Hebbeh, 13 July 2013 - 02:17 AM.

[Hebbeh]

I was referring to killer cell studies like this one:
Dietary supplementation with eicosapentaenoic acid, but not with other long-chain n-3 or n-6 polyunsaturated fatty acids, decreases natural killer cell activity in healthy subjects aged >55 y.
http://www.ncbi.nlm....pubmed/11237929

How do we know the immune system modulation wasn't due to a reduction in inflammation which would be a good thing? Realize the study was done in the elderly and I'm willing to bet they had excessive inflammation. It's another bad study because the control group didn't provide a reasonable cross reference of population (people of all ages and health levels). I don't think you can conclude anything from this study.

Also, I doubt populations that consume a high fish diet have compromised immune systems...quite frankly the opposite seems to be the case.

Edited by Hebbeh, 13 July 2013 - 02:30 AM.

[nameless]

I was referring to killer cell studies like this one:
Dietary supplementation with eicosapentaenoic acid, but not with other long-chain n-3 or n-6 polyunsaturated fatty acids, decreases natural killer cell activity in healthy subjects aged >55 y.
http://www.ncbi.nlm....pubmed/11237929

How do we know the immune system modulation wasn't due to a reduction in inflammation which would be a good thing? Realize the study was done in the elderly and I'm willing to bet they had excessive inflammation. It's another bad study because the control group didn't provide a reasonable cross reference of population (people of all ages and health levels). I don't think you can conclude anything from this study.

Also, I doubt populations that consume a high fish diet have compromised immune systems...quite frankly the opposite seems to be the case.

That's one of the studies where I am not sure if it's modulation or suppression. There are others though... it's just one I remembered. Some other issues could be due to excess oxidation if the fish oil doesn't have E or other antioxidants.

There was at least one study in a younger group that didn't show a reduction in NK cell activity (which I don't have a link to handy). Although one can assume it's simply modulating excess inflammation, we don't know that for certain... if some of the people happened to have cancer, I am not sure if reducing killer cell activity would be such a good thing. And as for populations who eat a lot of fish and their immune systems, I am not sure we can definitely say real fish is the same as fish oil.

But I just mentioned that as a possibility of a cause. I like the fish preparation idea from another poster. And if they didn't in fact take other risk factors into account, that also could skew things.

[kakker]

I am curious what some of you are planning on doing regarding fish oil supplements. Are you going to keep taking them? I have had a (very mild) case of idiopathic small fiber peripherial neuropathy since 2003. I have had no progression at all while taking r-lipoic acid, fish oil, methylcobalaminm and ALCAR (recently discontinued until the TMAO issue is sorted out). I have no way of knowing if the supplements have been responsible for my good fortune, but I don't know that I want to find out! I don't know what I am going to do yet regarding fish oil.

Edited by kakker, 13 July 2013 - 03:59 PM.

[Kevnzworld]

I will continue to take a moderate amount of fish oil 2g, with 1 g EPA/DHA. I've mentioned the following on other threads, but given the prostate cancer study it bears repeating.
PUFA's become rancid very quickly. Their shelf life if stored improperly isn't great. If consumed without adequate lipid soluable antioxidants one can have a higher level of lipid peroxidation.
It's important to check the expiration date, and consume only the freshest refrigerated fish oils from reputable manufacurers ( Nordic, Carlssons etc ). I also take gamma E, tocotrienols , CoQ10 and astaxanthin . They have been shown to mitigate lipid peroxidation.

[nameless]

I am curious what some of you are planning on doing regarding fish oil supplements.

How much fish oil do you take? At a reasonable dose, I wouldn't be overly concerned. For most people, I think a low dose would be all that is needed (300mg-ish). But if treating a specific issue, then it's basically down to risk/reward.

For myself, I have been on a bit of a fish oil hiatus the past 2 months due to stomach issues. If I can get that sorted out, I probably will go for something around 500mg or so ... whatever 1 pill of Nordic Naturals is, perhaps EOD. I previously was taking 2/daily, but would rather err on the side of caution.