A problem with the older studies that seemed to indicate that alcohol had health benefits was also that their control group, the people who didn’t drink, turned out largely not to do so because they already had severe medical problems. They weren’t allowed to drink because of them.
Compared to them it looked like the people who did drink were more healthy on average. So they concluded there must be health benefits to drinking alcohol.
A problem with the older studies that seemed to indicate that alcohol had health benefits was also that their control group, the people who didn’t drink, turned out largely not to do so because they already had severe medical problems. They weren’t allowed to drink because of them.
Compared to them it looked like the people who did drink were more healthy on average. So they concluded there must be health benefits to drinking alcohol.
This “Science VS” episode is about that (and has a bunch of citations in its transcript): https://gimletmedia.com/shows/science-vs/llhdgj