The so called "experts" don't know a damned thing about health... they're just making it up (and revising it) on the fly. Check out Lewis Black in his special "Black on Broadway" and listen to his take on the situation.
I've yet to see conclusive evidence that it matters... I've seen vegetarians who've had long healthy lives and ones who haven't... I've seen people who live off a diet consisting primarily of meat and only supplementing it with vegetables once a week and living healthy lives... I'm hedonistic when it comes to food and I have far less health issues than most of my friends who restrict their diets.