Vegetables are some of healthiest things that you can eat. So are meats, when they're unprocessed. We are made to eat them both!
I've been on the paleo diet for over a year and haven't been sick once! Whenever there's one of these flue waves going around and people warn about them I just chuckle to myself. Sometimes I feel some sinus issues and smile to myself and say: "I'll crush you in a day or two", and I do. =)