alt Hacker News> ...adjusting for other dietary factors, demographic variables, lifestyle behaviors, and comorbidities.
They give the data for the specific factors. What is the missing variable which explains their result?
Daily hours of sunlight? Average number of sudoku completions per day?
Sort of obvious, like dietary differences? They attempt a specific vegan control, but what if you aren't vegan but also dislike the taste of meat? What if you don't have a diagnosed health condition, but have a family history so you avoid eggs?
This isn't that complicated. Observational studies just have these weaknesses. We're past the point of observation here, as I said, and it's time to try intervention testing.