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. 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. Kidney beans contain a variety of bioactive plant compounds. Phytohaemagglutinin is a toxic lectin only found in raw or improperly cooked kidney beans. Kidney beans are high in protein and fiber and contain proteins that can reduce the digestion of starches (carbs), all of which may aid weight loss. Kidney beans are an excellent choice for people with type 2 diabetes and others who want to stabilize their blood sugar levels. They may also promote colon health and reduce your risk of colon cancer. Raw or improperly cooked kidney beans are toxic and should be avoided. What’s more, these beans contain antinutrients and may cause bloating, flatulence, and diarrhea in some people.