Chocolate (pronounced /ˈtʃɒklət/ ) is comprised of a number of raw and processed foods that are produced from the seed of the tropical cacao tree. Native to lowland, tropical South America, cacao has been cultivated for three millennia in Central America and Mexico, with its earliest documented use around 1100 BC. The majority of the Mesoamerican peoples made chocolate beverages, including the Maya and Aztecs, who made it into a beverage known as xocolātl, a Nahuatl word meaning "bitter water". The seeds of the cacao tree have an intense bitter taste, and must be fermented to develop the flavor. After being roasted and ground, the result is chocolate or cocoa.Much of the chocolate consumed today is made into bars that combine cocoa solids, fats like cocoa butter, and sugar. Chocolate has become one of the most popular flavours in the world. Gifts of chocolate molded into different shapes have become traditional on certain holidays: chocolate bunnies and eggs are popular on Easter, coins on Hanukkah, Santa Claus and other holiday symbols on Christmas, and hearts on Valentine's Day. Chocolate is also used in cold and hot beverages, to produce chocolate milk and hot cocoa.Chocolate contains alkaloids such as theobromine and phenethylamine which have physiological effects on the body. It has been linked to serotonin levels in the brain. Scientists claim that chocolate, eaten in moderation, can lower blood pressure. Dark chocolate has recently been promoted for its health benefits, including a substantial amount of antioxidants that reduce the formation of free radicals, though the presence of theobromine renders it toxic to some animals.