Containing a wealth of vitamins C, A, and K, and excellent sources of calcium, magnesium, potassium, manganese, and iron, bok choy deserves its reputation as a powerhouse among vegetables. Vitamin A, for instance, is essential for a properly functioning immune system, while vitamin C is an antioxidant that shields the body from free radicals. Bok choy supplies potassium for healthy muscle and nerve function, and vitamin B6 for carbohydrate, fat, and protein metabolism.