1. Subscribersonhouse
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    10 Jul '13 21:23
    http://medicalxpress.com/news/2013-07-link-omega-fatty-acids-prostate.html

    Men, don't take fish oil pills, now shown to increase the chance of prostate cancer by over 50%. That is a big number and has been confirmed.

    There is a large vitamin supplement industry pushing pills and more and more of them are found to be very harmful, not beneficial as the ads say.
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    10 Jul '13 21:39
    Looks like people need to stop eating fish lol.
  3. Cape Town
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    10 Jul '13 22:06
    Originally posted by sonhouse
    Men, don't take fish oil pills, now shown to increase the chance of prostate cancer by over 50%. That is a big number and has been confirmed.
    Then why does the article you link say 43%?

    And what is the risk of prostate cancer if you don't take the supplements? ie what is it a percentage of?

    I also notice later in the article:
    The analysis, which combined the data from 20 studies, found no reduction in all-cause mortality, heart attacks or strokes.

    You would think that if there was significant increased mortality, they would have picked it up too?
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    11 Jul '13 20:02
    Did they use purified fish oil? If not, then they would be giving people Mercury poisoning while they are at it. That would explain why there would be a negative effect.
  5. Standard memberDeepThought
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    12 Jul '13 01:50
    There is very little evidence that dietary supplements do anything other than harm. Most of the evidence for benefit is anecdotal and from people who are health conscious anyway. Whenever a randomized controlled trial is undertaken they find no effect or harms.
  6. SubscriberKewpie
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    12 Jul '13 05:551 edit
    Originally posted by twhitehead
    Then why does the article you link say 43%?

    70% for high-grade prostate cancers (the fatal ones), a much lower number for low-grade non-fatals, 43 is the overall average. The article is worth a proper read.
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    12 Jul '13 08:40
    Originally posted by Kewpie
    70% for high-grade prostate cancers (the fatal ones), a much lower number for low-grade non-fatals, 43 is the overall average. The article is worth a proper read.
    Yes, I did read it, and yes, I agree the evidence suggests taking omega-3 as a supplement has no overall benefits. However, just throwing out a percentage without stating what it is a percentage of, is meaningless to misleading. What percentage of the population actually get either type of cancer? Without knowing this, the stats cannot be used to judge my personal risk factors.
  8. Standard memberDeepThought
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    12 Jul '13 12:42
    Originally posted by twhitehead
    Yes, I did read it, and yes, I agree the evidence suggests taking omega-3 as a supplement has no overall benefits. However, just throwing out a percentage without stating what it is a percentage of, is meaningless to misleading. What percentage of the population actually get either type of cancer? Without knowing this, the stats cannot be used to judge my personal risk factors.
    Try typing something like: "prostrate cancer prevalence" into google and see what comes up. The reason for giving relative risks rather than absolute ones is because that is what is being measured. They see how many people get ill in the treatment group and compare that with the number that get ill in the control group. This tells them the effect of the treatment, which is what is of interest. They don't translate that into an overall risk because it's an additional source of error. Their study hasn't measured the prevalence figures for the population as a whole (who don't spend their days taking placebo pills). The absolute numbers aren't helpful from clinical point of view and require synthesis with data not collected in that study - so if there's a problem with the prevalence data it doesn't mess up their results.

    The percentage probably represents a risk ratio. A 44% increased risk means that people in the treatment group were 1.44 times more likely to get prostrate cancer than people in the control group. The real problem is that the article doesn't give the significance, or what the overall power of the study was, so it's hard to tell how seriously to take it.
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    12 Jul '13 18:34
    You might want to read up on the connection between Mercury poisoning and cancer in general.
  10. Cape Town
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    12 Jul '13 19:02
    Originally posted by DeepThought
    Try typing something like: "prostrate cancer prevalence" into google and see what comes up.
    Good advice.

    I get: 152.0 per 100,000 men

    So with fish oil it becomes: 217 per 100,000 men.
    Considering that the study had under 2000 men, of which about 3 would have normally had prostate cancer I wonder if the sample size was large enough. Anyone know enough statistics?
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    12 Jul '13 19:39
    http://www.michaelsavage.wnd.com/2013/07/dangers-of-fish-oils-and-prostate-cancer-based-on-flawed-science-says-dr-michael-savage/

    You might want to listen to this.
  12. Standard memberDeepThought
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    12 Jul '13 19:51
    Originally posted by Eladar
    http://www.michaelsavage.wnd.com/2013/07/dangers-of-fish-oils-and-prostate-cancer-based-on-flawed-science-says-dr-michael-savage/

    You might want to listen to this.
    Why would I want to listen to an extremist?
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    12 Jul '13 19:57
    Because he is interviewing a guy with credentials? Because he is a trained scientist?
  14. Standard memberDeepThought
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    12 Jul '13 20:484 edits
    Originally posted by twhitehead
    Good advice.

    I get: 152.0 per 100,000 men

    So with fish oil it becomes: 217 per 100,000 men.
    Considering that the study had under 2000 men, of which about 3 would have normally had prostate cancer I wonder if the sample size was large enough. Anyone know enough statistics?
    Look up "power (statistics)" on Wikipedia. It's not simple to calculate, and depends on details of how they did their study. The effect is fairly small, but 2,000 is fairly big by the standards of studies, some phase II trials have as few as 15 people in each arm. They've probably got enough power to make the claim. I'll see if I can access the original paper or not.

    Edit: The paper is free to download here: http://jama.jamanetwork.com/data/Journals/JAMA/5009/JRV50027.pdf
    I'll tell you what I think when I've read it.

    Edit 2: This is not the right paper. (But has good methods and finds no evidence that omega-3 either prevents or causes cancer).

    Edit 3: Here is the correct reference: http://jnci.oxfordjournals.org/content/early/2013/07/09/jnci.djt174.abstract?sid=4283f806-047c-4f33-9646-cbaa88c24e65
    It costs $32 for 1 days access to the paper. So I'm only reading the abstract.

    Edit 4: This is back to front. They found 863 people with prostate cancer and looked at their blood serum. More people who had cancer had high levels of omega-3. They've shown an association, but it could be that people with prostate cancer are at high risk of having omega-3 in their blood rather than the other way round. I'd avoid reading too much into this study. A better design would be to put 10,000+ people on a long term trial where one lot take omega-3 pills and the rest take smarties, and see who does better.
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    12 Jul '13 22:071 edit
    Originally posted by DeepThought
    Look up "power (statistics)" on Wikipedia. It's not simple to calculate, and depends on details of how they did their study. The effect is fairly small, but 2,000 is fairly big by the standards of studies, some phase II trials have as few as 15 people in each arm. They've probably got enough power to make the claim. I'll see if I can access the origi where one lot take omega-3 pills and the rest take smarties, and see who does better.
    and the rest take smarties,

    Careful! Smatties contain sugar and other ingredients that might indirectly effect the chances of getting cancer!
    (I remember a study sowing sugar encourage people to eat more thus leading to greater obesity. Then another study showing that obesity alone, even after filtering out other causal factors, increases the risk of many kinds of cancer)
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