Fascinating! The Adventist studies, especially Adventist 2, is the closest thing we have to a long-term randomized control trial in nutrition. It's fabulous.
They break it down into 5 types of Adventists — one who eat a little meat, three variations of vegetarians including pesco and lacto vegetarians, and vegans. I've deep-ended on the study and read a couple books about it and listened to the study director speak. The vegans really do stand apart in so many different ways, among them maintaining an average BMI of 22.5.