Comparison guide
Ceylon or cassia cinnamon?
Nearly every blood-sugar trial used cassia, and the result is a small drop in fasting glucose with an inconsistent effect on HbA1c. What really separates the two is coumarin: cassia is rich in this liver-toxic compound, while Ceylon has only trace amounts.
The options, compared
| Option | Evidence | Best for | The honest note | |
|---|---|---|---|---|
| Ceylon Cinnamon | Limited evidence | Regular daily use | Nearly free of coumarin, which is the main reason to choose it; its glucose benefit is extrapolated from cassia trials rather than shown directly. Look for Cinnamomum verum or zeylanicum on the label, since plain 'cinnamon' is usually cassia. | View |
| Cassia Cinnamon | Moderate evidence | Occasional, low-dose use | The type actually used in the glucose trials, most commonly 1–3 g/day, but a few grams a day can exceed the tolerable daily intake of coumarin. People with liver disease or on hepatotoxic drugs should prefer Ceylon. | View |
Our verdict
If you take cinnamon regularly, choose Ceylon: the blood-sugar effect of either type is small, and Ceylon avoids cassia's coumarin load. Neither replaces diabetes treatment, and both may add to the effect of glucose-lowering medication, so monitor if you take insulin or sulfonylureas.