What They Are
Nightshades are vegetables (actually they’re usually fruits that are eaten as vegetables) that are members of the Solanaceae family of plants. They include Paleo-friendly foods like tomatoes, tomatillos, peppers, eggplants, and potatoes (not sweet potatoes). Those are all healthy foods, right?
Yes, and not only can you include them as part of a healthy diet, you should be sure to do so. But not everyone can tolerate nightshades. Some people experience digestive issues and inflammation when they eat them. For that reason, whether you choose to include nightshades in your diet should be solely a matter of N=1. There’s no sense in eating food that bothers you, no matter what health benefits it may claim.
Mark Sisson gave nightshades a Primal pass for those of us who aren’t sensitive to them.