Author Topic: processed food and mortality  (Read 1017 times)

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Offline fred.slota

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Re: processed food and mortality
« Reply #15 on: February 13, 2019, 10:39:39 PM »
I'm still left with the conclusion that this study should not validate anything.  Correlation is not necessarily causation.

The point is that the reported relation between processed food and mortality is not mere correlation.  Rather, it is a relation observed after controlling for numerous potentially confounding variables.  This control can never be perfect, so it is rare that even the best prospective cohort study can be considered conclusive.  But you can't just brush the results off as "correlation."
Yes, I can, and with greater strength than just a brush.  "numerous potentially confounding variables"? Really? They controlled for six possible confounding variables.  Six.  By my count, that leaves, ummm, all the rest.

You can't just jump to "causation".


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Offline fred.slota

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Re: processed food and mortality
« Reply #17 on: February 14, 2019, 07:34:31 AM »
8 covariables.  Okay, now we're talking no other choice but to say this proves correlation.  I stand corrected.

Offline jt512

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Re: processed food and mortality
« Reply #18 on: February 14, 2019, 07:55:37 AM »
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You can't just jump to "causation".

You‘re right. You can’t „jump“ to conclusion. Nobody is. But the study is evidence in favor of causation. And due to the prospective cohort design and the statistical control, it is stronger evidence than mere correction.


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Offline jt512

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processed food and mortality
« Reply #19 on: February 14, 2019, 08:00:44 AM »

I certainly like the study results because it validates my prejudice against processed foods.

Snap.

At least he admits it.


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Offline jt512

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processed food and mortality
« Reply #20 on: February 14, 2019, 08:10:51 AM »
Just an observational study, but, something to consider.

https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2723626

Without being able to read the full article (it’s behind a paywall) it looks like a pretty good study.  And of course there’s the almost mandatory authors’ caveat that there’s a need for further prospective studies.  Although, how you’d do a prospective trial is a mystery to me.

The authors conclude that more prospective studies are needed, not necessarily prospective trials.  The study itself is a prospective study.

OK, I stand corrected.  It’s not a controlled study though.  People have to choose themselves to consume ultra-processed food, and they may differ in some significant way difficult to control for, although the authors tried to control for the factors they could think of.  People eating ultra-processed food may be under stress that can’t be quantified.

Prospective cohort studies, like the present, are classified as controlled studies.  The quality of the evidence is much greater than would be from an uncontrolled study, like a cross-sectional study.

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« Last Edit: February 14, 2019, 06:40:40 PM by jt512 »
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Offline fred.slota

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Re: processed food and mortality
« Reply #21 on: February 14, 2019, 09:15:21 AM »
Prospective cohort studies, like the present, are classified as controlled studies.  The quality of the evidence is much greater than would be from an uncontrolled study, like a cross-sectional study.

You‘re right. You can’t „jump“ to conclusion. Nobody is. But the study is evidence in favor of causation. And due to the prospective cohort design and the statistical control, it is stronger evidence than mere correction.

Yes, they are greater than uncontrolled.  And yes, they are stronger evidence.  But you are vastly overselling the improvement.

The base information in the study shows a linkage between ultraprocessed food and death.   Pure correlation.  Might be the cause, might be a side effect of some other cause.

Is this effect because UPF causes death, or because something else causes death and is linked with UPF? So you look at overweight people.  The study shows there is also a linkage between overweight people and death.  But control for weight, and you find that the UPF link is still present, independent of weight.  So the conclusion is stronger that UPF can cause death, independent of age.

You control for age, income, educational level, living alone and physical activity level, all of which the study shows are also linked with death, and you find that the UFP effect is still there despite all of those other influences.  Even stronger conclusion that UPF can cause death.

You've controlled for 6 factors.  6 very important factors.  You've got a stronger case.  But, there's still so much else in the world to consider.

Pre-existing conditions.  Depression.  Whether you have kids.  Left-handedness.  Being ginger.  Alcoholism. 

You are right to say that this study that attempted to control for some factors is better than an uncontrolled study.  I applaud them for doing that work.
You are right to say that this study better shows the possibility that UPF increases mortality.
You are right to say it is evidence in favor of causation.

But it is still a long way from being strong evidence, from being persuasive evidence. 




You shouldn't conclude aliens when you prove that a UFO isn't a satelite, weather balloon or bird.
You shouldn't conclude Nessie when you prove that a photo isn't shopped, a croc or a dolphin.
And you shouldn't conclude UPF causes death when you prove its not age, income or weight.

It might be an alien, Nessie or UPF.  But you still don't know.

This study should not validate your prejudice against UPF.

Offline jt512

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Re: processed food and mortality
« Reply #22 on: February 14, 2019, 12:48:09 PM »
Prospective cohort studies, like the present, are classified as controlled studies.  The quality of the evidence is much greater than would be from an uncontrolled study, like a cross-sectional study.


You‘re right. You can’t „jump“ to conclusion. Nobody is. But the study is evidence in favor of causation. And due to the prospective cohort design and the statistical control, it is stronger evidence than mere correction.

Yes, they are greater than uncontrolled.  And yes, they are stronger evidence.  But you are vastly overselling the improvement.

Please reread what I have written without reading anything into what I've written.  If after doing that you still think I'm "overselling" the study, please quote the statements that you feel constitute "overselling."

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You've controlled for 6 factors.  6 very important factors.  You've got a stronger case.  But, there's still so much else in the world to consider.

The investigators controlled for sex, age, income, education, marital status, urbanization, BMI, physical activity, smoking, alcohol intake, energy intake, family cancer history, family CVD history, overall diet quality, number of diet reports, reporting season, and death within three years of enrollment.  That's 17 factors.  I have no idea where you got 6 (or 8 ) from.

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You are right to say that this study that attempted to control for some factors is better than an uncontrolled study.  I applaud them for doing that work.
You are right to say that this study better shows the possibility that UPF increases mortality.
You are right to say it is evidence in favor of causation.

But it is still a long way from being strong evidence, from being persuasive evidence.

I doubt that the investigators care whether you applaud them or not.  Other than that, I agree with everything you wrote above.  This is not, however, the only evidence of processed foods increasing mortality.  The case is stronger when the totality of the evidence is considered.  That said, I agree with you that it is not completely convincing.  But that said, I think it is sufficient to warrant limiting one's consumption of processed foods.

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This study should not validate your prejudice against UPF.

Huh?  What makes you think I have a prejudice against UPF?  Are you confusing me with bachfiend?
« Last Edit: February 14, 2019, 06:38:01 PM by jt512 »
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Offline fred.slota

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Re: processed food and mortality
« Reply #23 on: February 14, 2019, 01:17:44 PM »
Sorry, linguistically my 'you's were/are a bit fluid.  I appear to have been you'ing directly to you, you'ing at other specific yous, and at other times you'ing at a rhetoric generic 2nd person you.

As to where I got 6, the full paper is behind a paywall.  The 6 I mentioned were the six mentioned in the Results section of the publicly readable section.

 

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