I recently discovered that there are two kinds of cinnamon: Ceylon, or “true” cinnamon, and cassia, which comes from a related, but different tree. It turns out that what we in the U.S. know as cinnamon is actually cassia; Ceylon cinnamon is generally not sold in stores. OTOH, in Europe, only Ceylon cinnamon can be sold as “cinnamon.” (I was reminded of this last night when one of the bakers on the Great British Baking Show mentioned she was going to use cassia bark in a recipe.)
The taste of Ceylon cinnamon is more subdued and subtle than that of cassia.
However, the more important difference, for some people at least, is that large doses of cassia can cause liver damage.
Due to a blood-thinning component called coumarin that could damage the liver if consumed in larger amounts,[7] European health agencies have warned against consuming high amounts of cassia.[8] Other bioactive compounds found in the bark, powder and essential oils of C. cassia are cinnamaldehyde and styrene. In high doses these substances can also be toxic for humans.[9]
I learned this alarming news a few months after my wife’s cardiologist advised her to start having smoothies for lunch with “heart-healthy” spices, including two teaspoons of cinnamon. He, and the author whose book he was citing, said nothing about the distinction between cassia and true cinnamon, so my wife has consumed over a pound of cassia since July. I am dismayed, to say the least.
I have discarded all our remaining cassia and bought a new supply of Ceylon cinnamon.