When I say I'm sceptical towards a vegetarian diet, it's not because of the things you'd miss because I accept that you can get all essential amino acids and vitamins and so on. What I'm sceptical towards is more what comes with those nutrients. In the study I quoted about autists behaviour in relation to diet, the change in behaviour is blamed on peptides derived from gluten. The ultimate answer to the problem is we have not evolved to eat starchy grains and so it affects us. In that study, it seems it changes the way autists respond to their environment -> it changes behaviour. More typical for such diet studies, it could be shown to be connected with lifestyle diseases.
A vegetarian diet will have us eat much more stuff we are not adapted to eating. This will cause changes in health and behaviour, just like gluten does. The reason it seems healthy, I think, is that it's now always compared to some idea of a normal western diet which probably includes stuff like fries and coka cola. If you compare a vegetarian diet to something like a paleolithic caveman diet, I think it would come out as worse. This is why I think a choice to be vegetarian is still a choice to be "unhealthy" ..
