Surgeon Atul Gawande in Complications implicates excess consumption of potatoes.  Potatoes have toxins that cause neural malformation in animal fetuses.
In addition, according to Norman Childers in Arthritis: Childers' Diet to Stop It - The Nightshades, Aging and Ill Health and Annemarie Colbin in Food and Healing, potatoes belong to a family of foods called nightshade (including potatoes, tomatoes, eggplant and peppers + tobacco) which are high in potassium and tend to throw off the calcium balance, unless dairy is added.