Easily the best health food grocery store in Florence, Naturasi served as my go-to market for most vegan staples. Complete with tofu, soy milk, dried fruits and nuts, and a surprisingly large selection of whole grain breads, cereals, and pastas that are not often available in the U.S. (their brown risotto rice verily impressed me as I have not found it yet back in the states). Their produce selection is a bit limited, though I happily bought it comforted by its organic quality (which can prove difficult to find in Italy). The only two products Naturasi lacks are nutritional yeast and flax seed oil, which I bought at De Herbore on Via Proconsolo near Piazza del Duomo.
See pictures and more restaurant reviews at my blog: http://farmersmarketvegan.wordpress.com/