Epidemiologic nutritional studies are proven to be totally useless. They literally are a questionnaire asking people what do they eat, take some health markers and drawing conclusions. I spent the morning reading through the data of that "plant-based diets reduce colorectal cancer" on the front-page of the Guardian [1], and it's yet another pile of cherry picked inconclusive crap people will keep sharing on social media.
From just 2 minutes with your paper: "Higher heme iron intake appeared to be
significantly associated with a 31 % (95 % CI 4–67 %)
elevated risk of developing CHD" --- lmao, loving that 95% confidence interval between 4 and 67%.
Passing those out as proof of real science keeps the disinformation and terrible practice alive. If I had a dime every time a random commenter gave me a link to an epidemiologic nutritional study, I could fund a double blind randomized one myself.
1: https://www.theguardian.com/science/2022/nov/29/plant-based-... — have fun reading the actual numbers in Tables 2, 3 and 4 of the linked paper.