POTATO is a nightshade plant. Gnocchi is made from nightshade potato flour. Some have experienced pain after indulging in a potato. Others have noticed a flare up of arthritis. Some have had dramatic potassium increases. Plants in this family are estrogen producing plants. Potatoes are also high in oxalates. Oxalates can be a problem for PKD'rs. Nightshade plants contain high amounts of solanine which interferes with calcium absorption.