Like its cousins, cauliflower and broccoli, kale is rich in fiber and beta-carotene. It is also an excellent source of calcium, iron, and vitamins A, C, and K. Part of what makes kale so healthy is its great quantity of phytochemicals, substances that have been shown to fight against a number of diseases, like cancer and cardiovascular disease. Kale also contains antioxidants to fight inflammation and detoxify the body and rid it of carcinogenic substances.