4 ms·

The first three grey Q&A boxes on the Harvard response are a pretty devastating rebuttal to the paper. To summarize: - 3 of the 5 meta-analyses reviewed suppo

by koboll 7y ago

The first three grey Q&A boxes on the Harvard response are a pretty devastating rebuttal to the paper. To summarize: - 3 of the 5 meta-analyses reviewed support the consensus on red meat's health dangers - The other 2 are irrelevant and shouldn't have been considered at all - The paper handwaves away the conclusions of the 3 by raising reliability issues that could be applied to any meta-analysis of nutrition, since it's impossible to perform nutritional research as rigorously as drug research

tomp 7y ago
Don't all 3 of those conflate red and processed meat? Not very sciency...
- amanaplanacanal 7y ago
  That's one of my personal pet peeves.
- TrinaryWorksToo 7y ago
  And there's a big difference too! We know nitrites aren't good for us, and can make meat red. But not all meat contains nitrites.
- scotty79 7y ago
  Isn't the most red meat consumed also processed? Don't know. Just asking. If so it would make sense to use it in research.
  - tomp 7y ago
    Maybe? Probably most food consumed is processed... but the advice should then be, eat unprocessed food (salad, steak, fruit not fruit juice, ...) In addition, some ways of processing food are likely less harmful... e.g. pickling vegetables and drying meat (without using nitrites, such as certain traditional EU PDO meats like Prosciutto di Parma).
    - scotty79 7y ago
      > but the advice should then be, eat unprocessed food I think it was not so much to give advice as to answer the question. Is that one thing that we are eating bad for us?
gwern 7y ago
> Among the five published systematic reviews, three meta-analyses basically confirmed previous findings on red meat and negative health effects. The sheer chutzpah of handwaving away the only paper that matters - the one meta-analyzing the randomized experiments - by counting a bunch of different confounded correlational approaches as each equal in value to it. Here is the only sentence you need to read: https://annals.org/aim/fullarticle/2752326/effect-lower-versus-higher-red-meat-intake-cardiometabolic-cancer-outcomes https://annals.org/aim/fullarticle/2752326/effect-lower-vers... 'Of 12 eligible trials, a single trial enrolling 48 835 women provided the most credible, though still low-certainty, evidence that diets lower in red meat may have little or no effect on all-cause mortality (hazard ratio [HR], 0.99 [95% CI, 0.95 to 1.03]'
- gyuserbti 7y ago
  Experiments have problems too. Let's say you successfuly blind people in a nutrition study (is this possible?). Randomized. How do you ensure they're following protocol? For how long? And who is adhering? How do you know you're manipulating what you think? Experiments introduce control at the expense of generalizability, and some types of experiments more so than others. Observational studies aren't perfect but they do have advantages, and in nutrition I wouldnt trust experiments more (maybe not less either to be fair). We have plenty of experiments in animals for example and those arent much more interpretable, at least in nutrition. Nothing is simple.
  - gwern 7y ago
    > Let's say you successfuly blind people in a nutrition study (is this possible?) What blinding do you need for all-cause mortality? Do you think people are lying on the form where the coroner says they are dead? > How do you ensure they're following protocol? For how long? And who is adhering? How do you know you're manipulating what you think? Every single problem here is far, far, far worse for all those observational studies you cite. > Observational studies aren't perfect but they do have advantages Their only advantages are that they make it cheap and easy to get the wrong answer precisely and churn out lots of papers and meta-analyses. Fortunately, here we have the more expensive, hard, but correct results. Guess what the second set of results say? > We have plenty of experiments in animals for example and those arent much more interpretable, at least in nutrition. Indeed. Because most nutrition research, especially the ones based on correlational results, are wrong. That's why the randomized experiments aren't 'interpretable': because the theories are wrong. You will indeed have trouble "interpreting" the results which keep showing all the theories are wrong. This is a feature, not a bug.

by koboll 7y ago

tomp 7y ago

Don't all 3 of those conflate red and processed meat? Not very sciency...

amanaplanacanal 7y ago
That's one of my personal pet peeves.
TrinaryWorksToo 7y ago
And there's a big difference too! We know nitrites aren't good for us, and can make meat red. But not all meat contains nitrites.
scotty79 7y ago
Isn't the most red meat consumed also processed? Don't know. Just asking. If so it would make sense to use it in research.
- tomp 7y ago
  Maybe? Probably most food consumed is processed... but the advice should then be, eat unprocessed food (salad, steak, fruit not fruit juice, ...) In addition, some ways of processing food are likely less harmful... e.g. pickling vegetables and drying meat (without using nitrites, such as certain traditional EU PDO meats like Prosciutto di Parma).
  - scotty79 7y ago
    > but the advice should then be, eat unprocessed food I think it was not so much to give advice as to answer the question. Is that one thing that we are eating bad for us?

gwern 7y ago

> Among the five published systematic reviews, three meta-analyses basically confirmed previous findings on red meat and negative health effects. The sheer chutzpah of handwaving away the only paper that matters - the one meta-analyzing the randomized experiments - by counting a bunch of different confounded correlational approaches as each equal in value to it. Here is the only sentence you need to read: https://annals.org/aim/fullarticle/2752326/effect-lower-versus-higher-red-meat-intake-cardiometabolic-cancer-outcomes https://annals.org/aim/fullarticle/2752326/effect-lower-vers... 'Of 12 eligible trials, a single trial enrolling 48 835 women provided the most credible, though still low-certainty, evidence that diets lower in red meat may have little or no effect on all-cause mortality (hazard ratio [HR], 0.99 [95% CI, 0.95 to 1.03]'

gyuserbti 7y ago
Experiments have problems too. Let's say you successfuly blind people in a nutrition study (is this possible?). Randomized. How do you ensure they're following protocol? For how long? And who is adhering? How do you know you're manipulating what you think? Experiments introduce control at the expense of generalizability, and some types of experiments more so than others. Observational studies aren't perfect but they do have advantages, and in nutrition I wouldnt trust experiments more (maybe not less either to be fair). We have plenty of experiments in animals for example and those arent much more interpretable, at least in nutrition. Nothing is simple.
- gwern 7y ago
  > Let's say you successfuly blind people in a nutrition study (is this possible?) What blinding do you need for all-cause mortality? Do you think people are lying on the form where the coroner says they are dead? > How do you ensure they're following protocol? For how long? And who is adhering? How do you know you're manipulating what you think? Every single problem here is far, far, far worse for all those observational studies you cite. > Observational studies aren't perfect but they do have advantages Their only advantages are that they make it cheap and easy to get the wrong answer precisely and churn out lots of papers and meta-analyses. Fortunately, here we have the more expensive, hard, but correct results. Guess what the second set of results say? > We have plenty of experiments in animals for example and those arent much more interpretable, at least in nutrition. Indeed. Because most nutrition research, especially the ones based on correlational results, are wrong. That's why the randomized experiments aren't 'interpretable': because the theories are wrong. You will indeed have trouble "interpreting" the results which keep showing all the theories are wrong. This is a feature, not a bug.