In addition to coffee, caffeine occurs naturally in tea, kola nuts, and ilex plants, as well as cocoa in small amounts. The substance can, however, also be prepared synthetically from uric acid and added to various consumables. In pure form it is odorless, somewhat bitter in taste, white, powdery, and soluble in water. The substance is also rapidly absorbed by the body, which distributes the caffeine through all of its tissues and fluids, producing a stimulating effect on the central nervous system, heart, kidneys, and blood vessels. The body rids itself of caffeine through metabolism and urination.