Walk into any supplement store and pick up a cinnamon capsule. The odds are good it is Cassia cinnamon, not Ceylon. The label might just say “cinnamon.” The marketing might imply health benefits. What it probably will not mention is the coumarin content, and that omission could matter for your liver.
Here is what the research actually says about Ceylon vs Cassia cinnamon, and why the difference is not just a marketing distinction.
The Coumarin Problem with Cassia Cinnamon
Coumarin is a naturally occurring compound found in significant amounts in Cassia cinnamon. It is the same compound used as a precursor in some blood-thinning drugs. At high enough doses, it is hepatotoxic, meaning it damages liver cells.
The numbers are stark:
- Cassia cinnamon: 1 to 12 mg of coumarin per gram of cinnamon
- Ceylon cinnamon: approximately 0.004 mg of coumarin per gram
The European Food Safety Authority (EFSA) established a tolerable daily intake (TDI) for coumarin at 0.1 mg per kilogram of body weight. For a 150-pound (68 kg) person, that is about 6.8 mg of coumarin per day as the upper safe limit.
One gram of mid-range Cassia cinnamon contains roughly 5 mg of coumarin. Most cinnamon supplement doses run 1,000 to 3,000 mg per day. Do the math: a person taking 2,000 mg of Cassia cinnamon daily could be consuming 10 mg or more of coumarin, well over the EFSA limit.
Regulatory Action Against Cassia Cinnamon
This is not theoretical concern. Regulators have acted on it.
Germany’s Federal Institute for Risk Assessment (BfR) issued consumer warnings about Cassia cinnamon, particularly for children and people taking it in supplement form. The BfR recommended limiting intake of Cassia-containing products specifically because of coumarin.
Some European countries have placed restrictions on Cassia cinnamon content in food products. Germany limits the amount allowed in certain foods sold to children. This is not about trace amounts; it is about regular supplement-level exposure.
The EFSA’s evaluation found that at doses used in supplements, Cassia cinnamon can push coumarin intake to levels where liver damage is a realistic concern in sensitive individuals, particularly those with pre-existing liver conditions or genetic variations in coumarin metabolism.
What Is Ceylon Cinnamon?
Ceylon cinnamon (Cinnamomum verum) is called “true cinnamon” for a reason. It originates primarily from Sri Lanka (formerly Ceylon), though it is also grown in Madagascar, Brazil, and India. The bark is thinner and more delicate than Cassia, and the flavor is notably sweeter and more complex.
The coumarin content is so low (0.004 mg/g) that it is effectively irrelevant at any normal supplement dose. Even at 6,000 mg per day, Ceylon cinnamon would deliver only 0.024 mg of coumarin total, a fraction of the EFSA limit for a person of any body weight.
Ceylon also contains cinnamaldehyde, cinnamic acid, and other polyphenols that appear to be responsible for its blood sugar benefits. These compounds are present in both Ceylon and Cassia, but Ceylon delivers them without the coumarin baggage.
How to Tell Which Type You Have
The quickest check is the Latin name on the label:
- Ceylon: Cinnamomum verum or Cinnamomum zeylanicum
- Cassia: Cinnamomum cassia, Cinnamomum aromaticum, or Cinnamomum loureiroi
If the label just says “cinnamon” with no species listed, assume it is Cassia. Ceylon is more expensive to source and producers who use it tend to say so prominently.
You can also look at the physical bark if you are buying whole cinnamon. Ceylon forms thin, multi-layered quills that crumble easily. Cassia is thicker, harder, and forms a single-layer curl. Cassia also tends to be darker and redder in color.
Are the Blood Sugar Benefits the Same?
This is a fair question. Most of the cinnamon blood sugar research used Cassia cinnamon, not Ceylon, partly because Cassia is cheaper and more available for research purposes. The Khan et al. 2003 Diabetes Care study that is most frequently cited used Cassia.
The active compounds in both types overlap significantly. Cinnamaldehyde and the procyanidin polyphenols that appear to improve insulin sensitivity are present in both. The mechanism of action, specifically AMPK activation and insulin receptor potentiation, does not require coumarin. There is good reason to expect that Ceylon provides similar blood sugar benefits without the coumarin risk.
Studies that have specifically used Ceylon cinnamon show positive results for blood glucose management. A 2013 study in the Journal of the Academy of Nutrition and Dietetics found Ceylon cinnamon improved postprandial glucose response in adults. The evidence base is smaller than for Cassia simply because less research has been done, not because Ceylon works less well.
The Only Reasonable Choice for Supplements
For someone eating a sprinkle of cinnamon on oatmeal occasionally, the coumarin from Cassia is unlikely to be a meaningful concern. The dose is low and infrequent.
For someone taking a cinnamon supplement daily at 1,000 to 3,000 mg, Cassia is not a reasonable choice. The coumarin math puts daily intake at or above established safety limits. Ceylon at the same dose delivers no meaningful coumarin exposure.
The conclusion is not complicated. For food use in small amounts, either type is fine. For supplementation, Ceylon is the only type that makes sense from a safety standpoint.
If you want to know what to look for when choosing a supplement, see our full guide: Best Ceylon Cinnamon Supplement of 2026.
Key Takeaways
- Cassia cinnamon contains 250 to 3,000 times more coumarin than Ceylon
- EFSA’s safe daily coumarin limit can be exceeded with just 1-2 grams of Cassia cinnamon
- Germany and other European regulators have issued warnings about Cassia at supplement doses
- Ceylon cinnamon provides the same active compounds for blood sugar support with negligible coumarin risk
- If a supplement just says “cinnamon” without specifying Ceylon or the Latin name Cinnamomum verum, assume it is Cassia