Ceylon cinnamon (Cinnamomum verum) is a type of cinnamon that comes from the bark of an evergreen tree. Sri Lanka provides about 80% of the world's supply.

The oils found in Ceylon cinnamon are thought to reduce spasms, reduce gas, and fight bacteria and fungi. Chemicals in Ceylon cinnamon might also work like insulin to lower blood sugar. But these effects are thought to be fairly weak.

People use Ceylon cinnamon for diabetes, indigestion, diarrhea, obesity, and many other conditions, but there is no good scientific evidence to support these uses.