People that don’t drink used to drink a lot or had other conditions that stopped them from drinking. This wasn’t taken into account when creating studies about it not drinking, and low drinking where done. This made it look like low drinkers fared better than non-drinkers. But non-drinkers were non-drinkers for an unhealthy reason. And that’s why we ended up with studies that said some drinking is healthier than none. But it turns out they were wrong. Because the non-drinkers they used had medical issues that prevented them from drinking and caused more problems.