Potatoes are dangerous! They belong to the evil Nightshade family and are related to such notorious plants as tobacco which is responsible for lung cancer and belladonna which is poisonous. Tomatoes are part of the family, too, as well as peppers and eggplant.
Seriously though, all Nightshades contain alkaloids (in case of potatoes solanine) which aren't exactly beneficial for you, though some may disagree. As a result, there has been a lot of speculations going on whether we should really stop eating potatoes and tomatoes. Especially potatoes are linked to arthritis and autoimmune diseases in general.
Others point out that the dangers of eating potatoes are likely exaggerated and many Nightshade plants are perfectly harmless and even provide various health benefits. This article, for instance, points out that tomatoes are more of a wonder food than health hazard since they contain lycopene, an antioxidant which can potentially prevent various forms of cancer.
Myself, I'm not convinced that potatoes, tomatoes and paprika are what brings so many people to an early grave, however, certain precautions may be not out of place, as of not eating green tomatoes and unpeeled potatoes. You can also try and substitute regular potatoes with sweet ones, which belong to the world healthiest foods.
Pity they are so expensive over here!