Tofu, also known as bean curd, is a food prepared by coagulating soy milk and then pressing the resulting curds into solid white blocks of varying softness; it can be silken, soft, firm, or extra firm. Beyond these broad categories, there are many varieties of tofu. It has a subtle flavor, so it can be used in savory and sweet dishes. It is often seasoned or marinated to suit the dish and its flavors, and due to its spongy texture it absorbs flavors well. It is most often treated as a meat substitute. It is a traditional component of East Asian and Southeast Asian cuisines, and has been consumed in China for over 2,000 years. Nutritionally, tofu is low in calories, while containing a relatively large amount of protein. It is high in iron, and can have a high calcium or magnesium content depending on the coagulants (e.g. calcium chloride, calcium sulfate, magnesium sulfate) used in manufacturing.