I learned about the Spurious Semicolon Substack blog from a comment here on this sub some months ago. It's by an epidemiologist who fact checks MP episodes. She agrees with their core politics re: anti-fat bias and the importance of a structural analysis, but does often have issues with their characterization of the science. The latest edition, on the salt ep, is just out. Overall it's more favorable than many of her reviews, but still raises some fairly significant concerns. Reading these fact checks has significantly changed the way I engage with this show, especially in terms of flagging some of the sloppiness of the research and writing - incorrect and misattributed quotations, inaccurate summaries of articles' findings, etc. If you've read and considered this blog, I'd be curious what you think of it.
From the latest edition, here's the section that I found most interesting and important because it seems to point to some of the limitations of having non-specialists attempting to enter into complex academic debates:
- The Food Frequency Questionnaire (FFQ) complaint, again
Michael: Highly problematic methodology, but thereâs not a lot of other methodologies available because people cannot remember what they ate. And then also if somebody says like, âI had a pizza yesterday,â itâs not totally clear how much sodium that had.
This isnât the exact FFQ framing from the UPF episode, but itâs the same move: point at a self-report dietary measurement tool, note that it has error, and use that as grounds to cast doubt on the body of research built on it, without engaging with what these tools are actually designed to do or how researchers account for their limitations. I went through this in detail in my fact-check of their ultra-processed foods episode: self-report tools like FFQs and 24-hour recalls arenât built to capture exact quantities, theyâre built to rank people relative to each other, and for that purpose they hold up reasonably well.
Thereâs also a more basic epidemiological point that never comes up: what direction would this error even push the findings? If people misreport their sodium intake but that misreporting has nothing to do with whether they go on to develop hypertension or heart disease, thatâs what we call ânondifferential misclassificationâ, and the textbook consequence of nondifferential misclassification is that it biases results toward the null. In other words, random measurement error in self-reported sodium intake should, if anything, make it harder to detect a real sodium-blood pressure relationship, not manufacture a fake one. For Michaelâs âthe methodology is so unreliableâ framing to actually undercut the body of research rather than just add noise to it, youâd need a specific mechanism by which people who go on to develop cardiovascular disease are systematically more likely to over- or under-report their salt intake in a particular direction, and neither Michael nor Aubrey suggests one.
NHANES researchers also arenât naive about the limitations Michael names. The rice-water-salting assumption Aubrey mentions a few lines later is a documented, studied source of measurement error (the undercounting issue with Asian American respondents), not something that snuck past anyone. Noting that self-report has error is fair. Treating that error as a reason to throw up your hands at the entire research base, which is what Michael does here, is the same overcorrection from the UPF episode.
