Go to the Green House, shop with the fishermen (or go fishing) and you will find a wide array of foods that fit your list.
There is also a small heath-food store in Belize City that stocks some otherwise hard to find supplements.
Thank you Diane.The fact that I will easily be able to keep ahold of my sugar levels through diet is very reassuring. It's nice to know that there is a health food store with the basics on the mainland, too!
Bob