People who follow the Paleo diet often do so for health reasons, eschewing many carbs, especially grains, in favor of lean meats and vegetables. Now, research indicates that this “caveman” style of eating may have hidden dangers to your heart health. The Paleo diet, which draws nutritional guidelines from the diets of our human ancestors, advocates eating like a hunter and gatherer—consuming lots of meat, vegetables, nuts, and some fruits—while excluding agriculturally-based foods such as grains, legumes, and dairy, along with refined sugar and processed oils. Though no one would argue the nutritional merits of vegetables and lean protein, pulling...