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Vegetarian dietary patterns associated with lower mortality

  1. Jun 4, 2013 #1

    Monique

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    A large-scale study published in JAMA Internal Medicine finds that vegetarian dietary patterns are associated with lower mortality (12% less). The association does not hold for British vegetarians, so there must be some additional differences that cause the effect.

    http://archinte.jamanetwork.com/article.aspx?articleid=1691919 [Broken]
     
    Last edited by a moderator: May 6, 2017
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  3. Jun 4, 2013 #2

    Simon Bridge

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    ... or that the vegetarians in the study tended to look after their health better in other ways as well (except the Brits - maybe it's the tea)? Perhaps adopting a vegetarian lifestyle makes people more aware of their health or people who adopt a vegetarian lifestyle tend to be more health-conscious that those who just go with the path of least resistance?

    There were 2570 deaths among 73 308 participants during a mean follow-up time of 5.79 years.

    "mean follow up time?" rises a red flag...
    presumably the distribution of follow-up times is in the main body of the work?
    if the vegetarians were followed up in a short time and the non-vegetarians after a long time, this would give slightly higher mortality rates for non-vegetarians... but I cannot check.

    USA death rate is 7.995/1000
    UK death rate is 6.236/1000
    (both age standardized, all-cause, for 2011 - using national stats databases)
    The sample managed 6.05/1000

    Don't know how the samples were selected by nationality.
    Not mentioned in the summary - but it says that they used North American 7th day adventists ... was the British thing a different study?

    But it looks like just being British has a similar effect on mortality rates to being in the sample. Could this explain why the British sample did not show much difference?

    Maybe the data reflects that the US meat eating population is more likely to be careless of their health rather than that the vegetarians are more likely to be careful?

    On a shallow reading, I think you are correct - there are other factors influencing the results. The concluding recommendation (everyone should be vegetarian) appears to overstate the significance of the findings.

    The ideal experiment would be long term on a closed community with a controlled diet - no self selection ... probably won't get that one past the ethics committee though.
     
  4. Jun 4, 2013 #3
    I know it sounds cheesy, but I do one of these babies everyday and they're great.

    https://www.youtube.com/watch?v=t3rQHwgjsWA

    I typically put kale, spinach, broccoli, collard greens, carrots, walnuts, ground flax, strawberries, apples, bananas, blackberries, and a combination of fresh blueberries and frozen blueberries (or any combination of the above). The frozen ones give it a cool, smoothie feel. Of course, all the ingredients are organic unless unavailable :smile:

    Edit: Oh yeah, and cleanup's a snap! :wink:
     
    Last edited: Jun 4, 2013
  5. Jun 4, 2013 #4

    Evo

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    Sounds awful. I know a lot of people like drinking this stuff, but I'd rather eat them. I just don't get blending everything into a liquid. WHY???? Why not just eat them?
     
  6. Jun 4, 2013 #5
    C'mon Evo, you don't like chompin on Kale, do you?
     
  7. Jun 4, 2013 #6

    Evo

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    I love cooked kale, I can't imagine drinking it, it's very bitter.

    I saw someone on tv baking "kale chips", so I tried it. OMFG, NOOOOO!! it was horrible, so bitter it was inedible. Do not do it!! People on tv do bad things and pretend it's ok, trust me, kale chips are inedible, if you have functioning taste buds.
     
    Last edited: Jun 4, 2013
  8. Jun 5, 2013 #7
    Simon, there is both pathophysiological and epidemiological studies implicating the role of meat in cardiovascular disease and cancer.

    There was a meta-analysis of seven cohort studies published in the Annals of Nutrition & Metabolism (http://www.ncbi.nlm.nih.gov/pubmed/22677895) which suggested a protective effect of a vegetarian diet on mortality. This did not include the study that Monique posted about. If it were included, it would have strengthened the finding.

    I agree with you that a randomised controlled trial (double-blind if it's somehow possible!) would provide the strongest evidence. This is not feasible. However, I pose to you this question: If we can accept the evidence that smoking is harmful for your health based on case-control and cohort studies, can we not accept that meat may be detrimental to your health based on the same type of studies?
     
  9. Jun 5, 2013 #8

    Simon Bridge

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    Yes but none of them are this paper. I have restricted my observations to the paper presented for discussion - I do hope you are not advocating blind acceptance of stuff that makes it past peer-review?

    In any case, you appear to be arguing against a position I have not taken.

    I have not, for instance, said that meat eating in not bad for you nor that the adoption of a vegetarian diet not good for you. All I have pointed out is that, from the information available to someone without a subscription to that journal, the article does not provide as much support for the authors recommendations (that these finding mean that everyone should be on a vegetarian diet) as the authors represent in their conclusion.

    The data does demonstrate that North Americans could lower their mortality rates by being more health-conscious ... maybe even by adopting a taxpayer-subsidized public heath service.

    What other studies show does not change the strength of this one - even if someone did a totally conclusive study coming to the same conclusions - I would not, on the information available, want to put this study next to it as support ... and neither should any pro-veg activist.

    OTOH: maybe it is better than it looks - I didn't get past the paywall. I had hoped that someone who did get past would be able to answer some of my questions.

    We certainly can. (my emph)

    The trick, as with the smoking studies, is to work out how harmful and in what way.
    The early smoking studies had a similar problem - perhaps smoking was a symptom and not the cause ... it took a while for the evidence to accumulate.

    Not eating meat may be harmful in other ways if vegetarians were as relaxed about their health as the average meat-eater. They would have troubles with iron and vitamin B12 for instance ...

    http://www.ncbi.nlm.nih.gov/pubmed/21139125
    http://ajcn.nutrition.org/content/90/4/943.full

    ... but I don't think there is any doubt it can be done with a health-conscious population and may well be a good idea. I don't know. But maybe just being careful with your health in general can have the same effect?

    Remember - journal articles are deliberately written for an audience of hardened skeptics. The whole point is to submit them scientific skepticism. There is too much "if you are not for us you are against us" mentality around food politics as there is. But you know all this already.

    -----------------------

    Aside - I have exactly this argument, but back the other way, with people promoting an almost-all-meat diet, no grains at all - the latest on the grounds that paleolithic humans ate lots of meat - citing studies showing some sort of benefit. Then there's people sold on some dietary suppliment with mega-doses of trace elements, vitamins, etc you know the kind.
     
  10. Jun 5, 2013 #9

    Monique

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    I can not answer in detail, because I'm stressed for time, but I want to remark that the authors do not suggest that everyone should be on a vegetarian diet. Their suggestion is to carefully consider the diet:
     
  11. Jun 5, 2013 #10

    D H

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    Color me skeptical. Would you believe a research study that claims benefits of drinking wine not just funded by but also performed by The Wine Institute? Of course not. This study came out of Loma Linda University. I'm skeptical of any dietary study performed under their auspices. They have a vegetarian agenda to push. Has there ever been a study out of Loma Linda that goes against the Seventh Day Adventist dietary rules? Show me one and I'll think of converting to vegetarianism. A hat eatin' vegetarianism.

    Comparing non-vegetarian Seventh Day Adventists with those who follow that faith's guidelines is particularly problematic. What other of the religions rules and guidelines did they break? Did the study control for drinking, smoking, caffeine? Partying late at night? Even if the studies did control for all of those influences, there's one they cannot control for. Non-vegetarian Seventh Day Adventists are, by definition, rule breakers. They are rebels. Non-conformists. Do rebels live shorter lives than conformists? Probably.
     
  12. Jun 5, 2013 #11
    You are a master of the straw-man argument Simon. I'll address some of the flaws in your argument in order of their appearance.

    "Yes but none of them are this paper." How would you know? You have not read the paper. Surely one should appraise the entirely of a work before coming to a conclusion.

    "I do hope you are not advocating blind acceptance of stuff that makes it past peer-review?" There is nothing I have said that would allude to this. I have submitted papers to peer review and been a reviewer. As with any process that involves humans, there's significant room for error.

    "In any case, you appear to be arguing against a position I have not taken." Your earlier conclusion was that there were other factors influencing the results. My argument was that this is likely not the case. So I am directly arguing against your position.

    "...the article does not provide as much support for the authors recommendations..." The authors conclusions were that "Vegetarian diets are associated with lower all-cause mortality and with some reductions in cause-specific mortality. Results appeared to be more robust in males. These favorable associations should be considered carefully by those offering dietary guidance." I think the paper supports this conclusion.

    "The data does demonstrate that North Americans could lower their mortality rates by being more health-conscious ... maybe even by adopting a taxpayer-subsidized public heath service." Which data? If we're restricting our observations to the paper presented, the data does not. Where does the data presented demonstrate that North Americans could lower their mortality rate through a taxpayer-subsidised public health service? There is no evidence of this in the body of the paper, and there certainly isn't in the abstract.

    "What other studies show does not change the strength of this one." You've confused what I wrote. What I stated was that if the study discussed here (Orlich et al, 2013) was included in the 2012 meta-analysis I mentioned, this would likely increase the effect size. Do you understand how a meta-analysis is performed?

    "The early smoking studies had a similar problem - perhaps smoking was a symptom and not the cause" This is simply not true. I did a recent review of the early literature on smoking and lung cancer for a lecture I gave. In 1958, a case-control study looking at cigarette smoking and lung cancer was published in the British Medical Journal. It demonstrated an exposure odds ratio for men of ~ 14 (p < 0.00001). I don't think the epidemiologists who undertook this study were ever under the impression that lung cancer led to cigarette smoking.

    "They would have troubles with iron and vitamin B12 for instance" This speculation, whilst commonly believed to be true, is not supported by evidence when it comes to the lacto-ovo vegetarian diet - the most common form of vegetarianism (https://www.mja.com.au/open/2012/1/2/iron-and-vegetarian-diets, https://www.mja.com.au/open/2012/1/2/vitamin-b12-and-vegetarian-diets).

    This study is the latest in a series of good quality studies examining diet and chronic disease. In light of the global burden of obesity and cardiovascular disease, these are pertinent studies. In my opinion, there is now sufficient evidence to suggest excessive red meat intake can be harmful to one's health. I work as a physician and while I never advice my patients to abstain from eating meat entirely, I do encourage them to moderate their intake, consistent with the evidence available at present.
     
  13. Jun 5, 2013 #12
    Haha, agreed.
     
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