I loved and went back three times to Be Bop. They have a separate vegan/gluten free menu and the staff answers all questions about ingredients: http://www.bebopristorante.com/
I had one meal at one of the Mens@Sana locations. this is a buffet type of place (no al you can eat, though) with healthy grains and greens etc.
not the best meal I had but solid and filling.
We had cake and coffee at Mudra Cafe, it sucks we came straight from be bop with full stomachs because their food looks great!
Their cakes are a bit pricey but the coffee is dirt cheap (and delicious) so it evened out in the end.
We had ice cream at Grom (a chain, I think) that marks their vegan option. they only had lemon when we went but usually have more flavors to pick from.
I was only there for a weekend and mostly walked around, went to the Casa Museo Boschi-di Stefano (it's free!) and had tons of cheap cheap and great espresso.
Here are my photos: http://www.flickr.com/photos/theknife/s ... 25/detail/
make sure to spin on the bull's balls! :)