The Solanaceae family of plants, commonly known as Nightshade vegetables or Nightshades, contains a diverse range of crops of over 2000 members with significant culinary, economic, and cultural importance. Familiar edible Nightshades include tomatoes, peppers, eggplants, and white potatoes. Many pharmacologically active compounds used in traditional medicine, including atropine and hyoscyamine, are derived from Nightshades. In addition to these beneficial pharmacologic agents, Nightshade-derived glycoalkaloid compounds, a key defense mechanism against predation, have been shown to disrupt intestinal epithelium and to potentially activate mast cells in the gut mucosa, leading to adverse symptoms in humans. There is a new appreciation that mast cell activation is an allergic inflammatory mechanism contributing both to pain in irritable bowel syndrome (IBS) and to gut inflammation in inflammatory bowel disease (IBD). Given their ubiquity in Western diets and their shared glycoalkaloid active compounds, edible Nightshades are attracting new interest as a potential trigger for worsening gut symptoms in functional and inflammatory gastrointestinal disorders. Here, we review the limited existing literature on the adverse effects of Nightshade consumption, including the effects of Nightshade-derived glycoalkaloids on IBD gut inflammation, and the under-recognized contribution of Nightshades to food allergies and allergic cross-reactivity. We then highlight new evidence on the contributions of mast cell activation to GI disorder pathogenesis, including potential linkages between Nightshade antigens, intestinal mast cells, and GI dysfunction in IBS and IBD.