Kidney beans are a variety of common beans (Phaseolus vulgaris), a legume native to Central America and Mexico. The common bean is an important food crop and a major source of protein throughout the world. Used in a variety of traditional dishes, kidney beans are usually eaten well cooked. Raw or improperly cooked kidney beans are toxic, but well-prepared beans can be a healthy component of a well-balanced diet. NUTRIENT CONTENT : Kidney beans are among the best sources of plant-based protein. They’re also rich in healthy fibers, which moderate blood sugar levels and promote colon health.