Blood Sugar

Ceylon or Cassia: How to Tell Which Cinnamon Is in Your Jar

By the Blood Sugar Balance editorial desk · Reviewed September 2026 · 6 min read

There are two things sold as cinnamon in American grocery stores, and they are not the same plant. One of them is the one nearly every blood sugar study was run on. The other is the one in almost every jar on the shelf.

Most labels say only "cinnamon." Federal labeling rules do not require the species, so the jar in your cabinet may not tell you which one you have been using. For someone adding a spoonful to oatmeal for the taste, this is trivia. For someone doing it because they read it might help with blood sugar, it is the whole question.

The two plants

Ceylon cinnamon comes from Cinnamomum verum, grown mainly in Sri Lanka. It is sometimes called "true cinnamon," which is a botanical description and not marketing.

Cassia cinnamon comes from related species grown mostly in Indonesia, China and Vietnam. It is cheaper to produce, and it is what the overwhelming majority of American supermarket cinnamon is made from.

They taste similar enough that most people never notice. They differ in one compound that matters.

Coumarin, and why the amount is not a footnote

Cassia contains coumarin, a naturally occurring compound that the liver has to process. Ceylon contains only trace amounts of it. European food safety authorities set a tolerable daily intake for coumarin, and analyses of cassia powder have found that a couple of teaspoons a day can approach or exceed it for a smaller adult.

This is the part that gets lost when a cinnamon tip circulates online. The advice is usually "take a spoonful daily." Nobody mentions that the daily part is exactly where the species stops being a detail.

How to tell them apart without a label

If you have sticks rather than powder, the difference is visible:

• How it rolls. Ceylon bark is thin and rolls into many fine layers, like a cigar made of paper. Cassia is a thick single curl, hollow in the middle, closer to a rolled piece of hardened bark.
• How it breaks. Ceylon crumbles easily between your fingers. Cassia is hard enough that you will look for a tool.
• Color. Ceylon runs tan and light brown. Cassia is darker, more reddish.
• Smell. Ceylon is milder and slightly sweet. Cassia is sharper and more aggressive, which is why it dominates in baking.

Powder is harder. Ceylon powder is usually lighter in color and finer, but at that point the honest answer is that you are relying on the label. If a product does not name the species anywhere on the package, it is almost certainly cassia. Producers who go to the expense of sourcing Ceylon say so, because it is the reason their product costs more.

What the research actually looked at

Interest in cinnamon and blood sugar goes back to work published in the early 2000s, and the literature since then is genuinely mixed. Some trials found modest changes in fasting glucose. Others found nothing measurable. Reviews have repeatedly pointed at the same set of problems: small groups, short study windows, and no standardization of what "cinnamon" meant from one study to the next.

That last problem is the interesting one. Studies used different species, different parts of the bark, different extraction methods and wildly different amounts. When a review pools trials that were not testing the same substance, "mixed results" is close to the only possible outcome.

The reasonable reading is not that cinnamon is proven and not that it is debunked. It is that the question was never asked cleanly enough to answer, and that the version most people are using at home — an unstandardized scoop of an unnamed species — is not the version anyone was studying.

Where this leaves a person at home

If you are going to do this daily, the species matters and the amount matters, in that order. Cassia and Ceylon are not interchangeable for a daily routine, and a kitchen spoon is not a measurement. Neither is a reason to expect a spice to do the work of managing a chronic condition, and none of this replaces what your doctor is monitoring.

It does explain why two people can follow the same advice for three months and have completely different experiences with it.

Continue reading The Real 30-Second Cinnamon Ritual A longer look at how the concentrated form is standardized, what a usable daily amount actually is, and the routine built around it.