Black tea contains an abundant source of natural plant-derived antioxidant compounds called polyphenols that aid in fighting harmful free radicals. Research shows that these free radicals can cause heart disease, cancer and increase the risk of strokes. Drinking black tea with its high antioxidant levels may help protect the body by combating harmful free radical activity. Further health benefits of black tea may include lowering cholesterol, strengthening the immune system, promoting healthy blood vessel functionality and even protecting teeth and bones. In addition, black tea provides a source of nutrients including magnesium, managanese, potassium, calcium, and the vitamins C and K all in trace amounts.