The pigments in produce are healthful, and the peels or skins of fruits and vegetables are often the most colorful part. Colorful peels can be a concentrated source of potentially beneficial phytochemicals.
Apple peels may also help prevent cancer. Lab research has found that whole apples have a much greater effect on cancer cells than peeled ones, probably because of antioxidants in the apple skin.
You don’t need to wash fruits and vegetables with soap—plain water is fine. It will remove nearly all dirt, as well as bacteria and some pesticide residues, if any, on the surface. Scrub firmer produce like potatoes with a vegetable brush. The wax on cucumbers, apples, tomatoes and eggplants is harmless.