Claim: Fish oil supplements increase prostate cancer risk

Though I’m skeptical of the link with prostate cancer (weak statistical results), the important part of this study is…

… the finding that:

The analysis, which combined the data from 20 studies, found no reduction in all-cause mortality, heart attacks or strokes.

… which is the reason to buy these supplements in the first place.

The media release is below.

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Study confirms link between omega-3 fatty acids and increased prostate cancer risk

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

SEATTLE – A second large, prospective study by scientists at Fred Hutchinson Cancer Research Center has confirmed the link between high blood concentrations of omega-3 fatty acids and an increased risk of prostate cancer.

Published July 11 in the online edition of the Journal of the National Cancer Institute, the latest 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.

The increase in risk for high-grade prostate cancer is important because those tumors are more likely to be fatal.

The findings confirm a 2011 study published by the same Fred Hutch scientific team that reported a similar link between high blood concentrations of DHA and a more than doubling of the risk for developing high-grade prostate cancer. The latest study also confirms results from a large European study.

“The consistency of these findings suggests that these fatty acids are involved in prostate tumorigenesis and recommendations to increase long-chain omega-3 fatty acid intake, in particular through supplementation, should consider its potential risks,” the authors wrote.

“We’ve shown once again that use of nutritional supplements may be harmful,” said Alan Kristal, Dr.P.H., the paper’s senior author and member of the Fred Hutch Public Health Sciences Division. Kristal also noted a recent analysis published in the Journal of the American Medical Association that questioned the benefit of omega-3 supplementation for cardiovascular diseases. The analysis, which combined the data from 20 studies, found no reduction in all-cause mortality, heart attacks or strokes.

“What’s important is that we have been able to replicate our findings from 2011 and we have confirmed that marine omega-3 fatty acids play a role in prostate cancer occurrence,” said corresponding author Theodore Brasky, Ph.D., a research assistant professor at The Ohio State University Comprehensive Cancer Center who was a postdoctoral trainee at Fred Hutch when the research was conducted. “It’s important to note, however, that these results do not address the question of whether omega-3’s play a detrimental role in prostate cancer prognosis,” he said.

Kristal said the findings in both Fred Hutch studies were surprising because omega-3 fatty acids are believed to have a host of positive health effects based on their anti-inflammatory properties. Inflammation plays a role in the development and growth of many cancers.

IMAGE: Corresponding author Theodore Brasky, Ph.D., a research assistant professor at the Ohio State University Comprehensive Cancer Center, was a postdoctoral trainee at Fred Hutch when the reserach was conducted.
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It is unclear from this study why high levels of omega-3 fatty acids would increase prostate cancer risk, according to the authors, however the replication of this finding in two large studies indicates the need for further research into possible mechanisms. One potentially harmful effect of omega-3 fatty acids is their conversion into compounds that can cause damage to cells and DNA, and their role in immunosuppression. Whether these effects impact cancer risk is not known.

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.

The current study analyzed data and specimens collected from men who participated in the Selenium and Vitamin E Cancer Prevention Trial (SELECT), a large randomized, placebo-controlled trial to test whether selenium and vitamin E, either alone or combined, reduced prostate cancer risk. That study showed no benefit from selenium intake and an increase in prostate cancers in men who took vitamin E.

The group included in the this analysis consisted of 834 men who had been diagnosed with incident, primary prostate cancers (156 were high-grade cancer) along with a comparison group of 1,393 men selected randomly from the 35,500 participants in SELECT.

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15 responses to “Claim: Fish oil supplements increase prostate cancer risk

  1. Maybe it’s better to eat beneficial fish than just taking the oils as suppliments.

  2. I once took 6 grams of fish oil a day for a while till I started having nose bleeds at night. Reduced to 3 grams, nose bleeds stopped. Anecdotal conclusion : taking fish oil does in fact influence blood clotting and could have beneficial effect if taken in moderation.

  3. A balance in the diet is needed between omega 3 alpha linoleic acid and linoleic (Omega 6 fatty acid) which is way out of balance in present day food “products”, and this is best obtained by avoiding man-made spreads like that used to be called margarine, but which now have fancy names, and contain hydrogenated, and partially hydrogenated oils (which are worse) containing dangerous trans fats. Sunflower, corn, soybean and canola oils contain excess Omega six. The best foods to create a normal balance are a moderate amount of fish, natural seeds and nuts, and a moderate amount of unprocessed (virgin) olive oil. Nothing wrong with a bit of butter as well. Of course this study refers ro males, but could have implications for females too. Stick to good quality foods that our ancesrors ate before modern technology intervened to make millionaires out of suckers.

    • I thought Canola oil was suppose to be relatively high in Omega 3 which is why we are encouraged to use it in cooking, and why it has a subtle fishy smell to it. I have to say, during cooking much of the Omega 3 gets destroyed. Eat more sushi.

      • Marque2, my understanding is that the processing involved in producing canola oil can produce trans fats up to 4.6% of volume. If hydrogenated as well this content may be raised to as high as 40%. OK, the Canadian government authorities list the transfat of canola at a minimal 0.2%, but research at the University of Florida, Gainesville has found levels as high as 4.6% in commercial canola oil. Trans fat in canola oil is usually not listed on labels. It was not used by our ancestors. I would avoid it.

  4. “dangerous trans fats”

    Where are the bodies?

  5. Used to take fish oil supplements but after about 4 days they left such a taste in my mouth I quit taking them. Can’t go around smelling like a fish processing plant.

  6. You’re not supposed to chew them!

    • Farmer: That supplement from the vet sure perked up my bull.
      Farmer2: What’s in it?
      Farmer: I dunno but it tastes minty.

  7. We analyzed the study already (see our blog), but “… which is the reason to buy these supplements in the first place” is overly simplistic. Quality of life can vastly change, regardless of mortality.

  8. Take a look at Sol’s analysis. It is simple to follow, clear, and puts the lie to the headline.

  9. The bodies, Gamecock, will be found in the morgue. Hopefully you and I will not be among them. Trans fats apparently increase deposition of LDL cholesterol in arteries which can have nasty results

  10. In my opinion, I felt that the researchers in this study—as well as others they reported on–had a negative bias against nutritional supplements. This wasn’t a double-blind, placebo controlled trial about omega-3s—in fact, we don’t even know if the participants in this study took omega-3s. Instead, the researchers drew a conclusion based on a.2% difference in omega-3s—one that can show association, but not causation.

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