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I see this as an epistemological failure in nutrition that plagues other fields as well. We have all this knowledge of human physiology and metabolism, and make

I see this as an epistemological failure in nutrition that plagues other fields as well. We have all this knowledge of human physiology and metabolism, and make very little use of it in nutrition, acting as though we can't draw logical conclusions from what we know about those things, or trust those conclusions, or at least use them to apply serious skepticism to the apparent implications of low-quality data. For myself, until you can tell me by what means a particular food produces the claimed outcome, I dismiss your epidemiological nutrition study.

andrewf 7y ago
We have all this knowledge of human physiology and metabolism I think the depth of knowledge is very uneven. We're not sure how Tylenol works. (Disclaimer: I work in software, not bioscience)
- nzzzz 7y ago
  There will never be explanations on "how paracetamol (the principal substance of tylenol) works" because.. it doesn't work. It doesn't fare better than placebo. https://www.evidentlycochrane.net/paracetamol-widely-used-ineffective/ https://www.evidentlycochrane.net/paracetamol-widely-used-in... At least, placebos don't harm the user. There's evidence paracetamol is harmful. https://ard.bmj.com/content/75/3/552 https://ard.bmj.com/content/75/3/552 And dosages higher than 4g/day are known to destroy the liver. Paracetamol overdose is one of the most painful way to kill yourself. Its abuse being freely sold over the counter makes it the number one cause of liver failure in the US and UK. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1403265/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1403265/ >Paracetamol’s toxicity is also the single biggest cause of acute liver failure in the United States. Cases have been rising for six years, according to a study published in December (Hepatology 2005;42:1364-72). By 2003, the drug accounted for just over half the cases of acute liver failure, and about half of these cases were the result of unintentional overdose. It boggles the mind the substance has not been put under harsher control yet.
  - circlefavshape 7y ago
    Looks to me like you're over-generalizing. From skimming that article it appears that paracetamol is ineffective against chronic page, not the headache/hangover that most people use it for
- trappist 7y ago
  That's medicine, where the use of much better techniques are feasible and appropriate than in nutrition. What I'm saying isn't true of all fields. I'd put nutrition and economics near the top of the list, and medicine much further down.
o09rdk 7y ago
Although I think that's reasonable at some level, I think there's dangers in it as well, in that I don't think we really know that much about metabolism or physiology in the grand scheme of things. Physiological and microbiological studies are plagued by confounds and unreplicability problems, for example, and even where it's not, our understanding is more meager than many think. Trying to tie population-level findings to physiology is great if it's possible, but I don't see it as necessary on either end, at least for awhile. It wasn't that long ago that the role of microbiome was recognized, for example, and even now it's contentious. Conversely, scores of epidemiological findings have had nice physiological explanations that turned out to be much more complicated, like those involving saturated fat, cholesterol, and carbohydrates. DHA, omega fatty acids, etc. are similar. Physiology is complex enough that you can accommodate just about any finding. To carry this a bit further, it can be problematic going in the other direction too, from physiology to populations. Some of the anti-sugar advocacy, for example, was rooted in lab studies that neglected the effect of fiber in digestion of fruit, so you had people advocating that whole fruit consumption be avoided based on incomplete understanding. It's hard to argue that unprocessed whole fruit is undesirable on the basis of observational nutrition studies. Someone looking at the wet lab data and advocating abandonment of whole fruits might have done well to look at those observational studies to see why different trends were occurring. I'm not saying that tying one level to the other at some point isn't necessary. I just think one or the other level can't be dismissed out of hand just because things don't map onto each other initially. It's possible that one level provides clues that the other is missing; it's also possible to come up with plausible but wrong bridges between the two levels.

andrewf 7y ago

We have all this knowledge of human physiology and metabolism I think the depth of knowledge is very uneven. We're not sure how Tylenol works. (Disclaimer: I work in software, not bioscience)

nzzzz 7y ago
There will never be explanations on "how paracetamol (the principal substance of tylenol) works" because.. it doesn't work. It doesn't fare better than placebo. https://www.evidentlycochrane.net/paracetamol-widely-used-ineffective/ https://www.evidentlycochrane.net/paracetamol-widely-used-in... At least, placebos don't harm the user. There's evidence paracetamol is harmful. https://ard.bmj.com/content/75/3/552 https://ard.bmj.com/content/75/3/552 And dosages higher than 4g/day are known to destroy the liver. Paracetamol overdose is one of the most painful way to kill yourself. Its abuse being freely sold over the counter makes it the number one cause of liver failure in the US and UK. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1403265/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1403265/ >Paracetamol’s toxicity is also the single biggest cause of acute liver failure in the United States. Cases have been rising for six years, according to a study published in December (Hepatology 2005;42:1364-72). By 2003, the drug accounted for just over half the cases of acute liver failure, and about half of these cases were the result of unintentional overdose. It boggles the mind the substance has not been put under harsher control yet.
- circlefavshape 7y ago
  Looks to me like you're over-generalizing. From skimming that article it appears that paracetamol is ineffective against chronic page, not the headache/hangover that most people use it for
trappist 7y ago
That's medicine, where the use of much better techniques are feasible and appropriate than in nutrition. What I'm saying isn't true of all fields. I'd put nutrition and economics near the top of the list, and medicine much further down.

o09rdk 7y ago

Although I think that's reasonable at some level, I think there's dangers in it as well, in that I don't think we really know that much about metabolism or physiology in the grand scheme of things. Physiological and microbiological studies are plagued by confounds and unreplicability problems, for example, and even where it's not, our understanding is more meager than many think. Trying to tie population-level findings to physiology is great if it's possible, but I don't see it as necessary on either end, at least for awhile. It wasn't that long ago that the role of microbiome was recognized, for example, and even now it's contentious. Conversely, scores of epidemiological findings have had nice physiological explanations that turned out to be much more complicated, like those involving saturated fat, cholesterol, and carbohydrates. DHA, omega fatty acids, etc. are similar. Physiology is complex enough that you can accommodate just about any finding. To carry this a bit further, it can be problematic going in the other direction too, from physiology to populations. Some of the anti-sugar advocacy, for example, was rooted in lab studies that neglected the effect of fiber in digestion of fruit, so you had people advocating that whole fruit consumption be avoided based on incomplete understanding. It's hard to argue that unprocessed whole fruit is undesirable on the basis of observational nutrition studies. Someone looking at the wet lab data and advocating abandonment of whole fruits might have done well to look at those observational studies to see why different trends were occurring. I'm not saying that tying one level to the other at some point isn't necessary. I just think one or the other level can't be dismissed out of hand just because things don't map onto each other initially. It's possible that one level provides clues that the other is missing; it's also possible to come up with plausible but wrong bridges between the two levels.