Cassia (Cinnamomum Aromaticum) is a close relative to Cinnamon (C. Verum, C. Zeylanicum, or "true cinnamon"), Saigon Cinnamon (C. loureiroi, also known as "Vietnamese cinnamon"), Camphor laurel (C.Camphora), Malabathrum (C. tamala), and Indonesian cinnamon (C Buramannii). Read customer reviews on Ceylon Cinnamon from around the world.
Cassia's flavour, however is less delicate than that of true Cinnamon; for this reason,Cassia is less expensive. Cassia is sometimes called "bastard Cinnamon".
There is a natural constituent contained in all types of Cinnamon known as coumarin. Some European countries have done safety studies on this component of Cinnamon and believes it can cause damage in some who are sensitive (although the damage is not permanent) and if taken in doses too high (as you might during a holiday season) can be detrimental to your health.
Here is an excerpt from the organization known as the BFR which is the Institute for Risk Assessments in Germany of various substances, especially food.
Whole branches and small trees are harvested for Cassia bark, unlike the small shoots used in the production of Cinnamon this gives cassia bark a much thicker and rougher texture than that of true Cinnamon.
Most of the spice sold as Cinnamon in the United States and Canada (where true cinnamon is still generally unknown) is actually Cassia. In some cases, Cassia is labeled "Chinese Cinnamon" to distinguish it from the more expensive True Cinnamon (C. verum), which is the preferred form of the spice used in South America and Europe. "Indonesian Cinnamon" can also refer to C.Burmannii), which is also commonly sold in the United States, labeled only as Cinnamon.
Cassia (C. Aromaticum) is produced in both China and Vietnam. Until the 1960s, Vietnam was the world's most important producer of Saigon Cinnamon (C.Lloureiroi), a species which has a higher oil content than Cassia, and consequently has a stronger flavor. Saigon cinnamon is so closely related to Cassia that it was often marketed as Cassia (or, in North America, "Cinnamon").Of the three forms of Cassia, it is the form which commands the highest price.
Because of the disruption caused by the Vietnam War, however, production of C. Burmannii, in the highlands of the Indonesia on island of Sumatra, was increased to meet demand, and Indonesia remains one of the main exporters of Cassia today. Indonesian cassia has the lowest oil content of the three types of Cassia and, consequently, commands the lowest price.
Saigon cinnamon, only having become available again in the United States since the early 21st century, has an intense flavour and aroma and a higher percentage of essential oils than Indonesian cassia. Cassia has a stronger and sweeter flavor, similar to Saigon Cinnamon, although the oil content is lower. In China (where it is produced primarily in the southern provinces of Guangxi, Guangdong, and Yunnan ) Cassia is known as Tung Hing.
Cassia bark (both powdered and in whole, or "stick" form) is used as a flavouring agent for candies, desserts, baked goods, and meat; it is specified in many curry recipes, where cinnamon is less suitable. Cassia is sometimes added to true cinnamon but is a much thicker, coarser product. Cassia is sold as pieces of bark (as pictured below) or as neat quills or sticks. Cassia sticks can be distinguished from true cinnamon sticks in the following manner: Cinnamon sticks have many thin layers and can easily be made into powder using a coffee or spice grinder, whereas cassia sticks are extremely hard, are usually made up of one thick layer, and can break an electric spice or coffee grinder if one attempts to grind them without first breaking them into very small pieces.
Cassia buds, although rare, are also occasionally used as a spice. They resemble cloves in appearance and have a mild, flowery cinnamon flavor. Cassia buds are primarily used in old-fashioned pickling recipes, marinades, and teas.