Unprocessed means untreated with preservatives. Smoked, salted, dried, potassium benzoate, etc. The evidence I'm referencing is a meta-review of epidemiological studies. The lack of a causal pathway refers to the failure to find anything when doing intervention studies on particular substances. So it could very well be that the epidemiological studies are all failing to properly control for confounding factors. Nutritional self reporting is notoriously terrible. Epidemiological studies often rely on spaced surveys, sometimes asking questions about food habits over an entire year. That people are unable to provide accurate info is unsurprising. Still, it is not zero evidence.
My own hypothesis is that the animal's diet has a lot more to do with the potential harm to you than currently realized. Animals with crappy diets are sickly. We likely have a natural aversion to eating sickly animals for a reason.
Uh, yeah. The reason for that is that sickly animals carry parasites. It is logical that we wouldn't want to eat parasite-ridden or diseased animals, because then WE get the parasites. If the animal is not parasite-ridden, there's no good reason to believe it would be unhealthy to eat.
My personal suspicion for the cause is underlying SES factors (wealthy people tend to eat better, fresher food than the poor) as well as the simple issue of dietary selection - people who watch what they eat are also more likely to exercise and generally have healthier habits than those who are willing to eat anything.
There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.
Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.