No, your mother did not lie to you when she said that green stuff is amazingly healthy. Kale, broccoli, and cabbage are indeed nutrient-rich and high-fiber vegetables that you need to ingest in order to have a strong digestive system. However, these foods are also rich in raffinose, which is a sugar that can only be digested by the bacteria in your stomach and its fermentation is exactly what causes you to bloat.