What is cinnamon? A plain guide

A cinnamon supplement is the dried inner bark of a Cinnamomum tree, ground into powder or concentrated into an extract and put into a capsule or tablet. Two species dominate the market — cassia and Ceylon — and the difference between them matters more than most labels let on, mainly because of a compound called coumarin.

Two different plants sold under one name

Most of what's sold as "cinnamon" — in the grocery aisle and in supplement capsules — is cassia (Cinnamomum cassia, also called C. aromaticum or Chinese cinnamon): a single thick curl of bark, reddish-brown, with a sharp, spicy-hot flavor. Ceylon cinnamon (Cinnamomum verum, sometimes marketed as "true cinnamon") comes from a different tree, forms thin, multi-layered quills, and has a milder, sweeter flavor. Labels don't always say which one is inside; "cinnamon" alone, with no species named, is cassia more often than not.

The species matters because of coumarin, a naturally occurring aromatic compound. A 2012 analysis of 60 ground cinnamon samples from twelve retail brands found coumarin levels averaging 2,650 to 7,017 mg per kilogram in the cassia-derived samples; a single Ceylon sample, sourced directly from a Sri Lankan plantation and tested in the same study, had none. The gap is large enough that European food-safety regulators set a tolerable daily intake for coumarin — 0.1 mg per kilogram of body weight, or about 7 mg a day for a 70 kg adult — largely because of how much cassia cinnamon can contribute to a day's total. Cinnamon dosage works through what that means in grams.

Cinnamaldehyde and coumarin are not the same thing

Cinnamaldehyde is the compound responsible for cinnamon's characteristic smell and flavor, and it's present in both cassia and Ceylon. Coumarin is a separate compound, present in far larger amounts in cassia than in Ceylon, and it's coumarin — not cinnamaldehyde — that drives the safety limit above. A label that advertises "high cinnamaldehyde content" isn't telling you anything about coumarin exposure, and vice versa.

How it's sold as a supplement

Capsules and tablets generally contain one of two things: ground bark powder (cassia or Ceylon, at gram-level doses) or a concentrated water-soluble extract, standardized to a specific compound class and used at a much lower milligram dose. The two aren't interchangeable gram for gram — a capsule labeled "500 mg cinnamon extract" is not a twentieth of a 10 g bark dose; it's a differently processed product with its own separate literature. How to choose a good cinnamon covers what to check on a label before assuming one form for the other.

What it is as a food

As a spice, a teaspoon of ground cinnamon (about 2.6 g) provides roughly 6 calories and a meaningful amount of manganese, according to USDA FoodData Central. That's a small fraction of what most supplement capsules or trial doses provide — culinary use and supplement use aren't really the same exposure.

What people take it for

Cinnamon is one of the most-searched supplement ingredients tied to blood sugar, and that's almost entirely what the human research on it has looked at. Cinnamon benefits: what the research does and doesn't show and blood sugar supplements: what the evidence supports cover what those trials found and didn't find. This page sticks to what cinnamon is, not what it does.

Questions people ask

Why take a cinnamon supplement?

Most people buy one hoping it will affect blood sugar — that's the research question almost every human trial has tested. Whether the evidence actually supports that at typical supplement doses is a separate question, covered in cinnamon benefits.

What is a Ceylon cinnamon supplement?

It's a capsule or tablet made from Ceylon cinnamon bark (Cinnamomum verum) rather than the more common cassia. The main practical difference is coumarin content, which runs consistently low in Ceylon and highly variable in cassia.

Does cinnamon supplement thin your blood?

Cinnamon's coumarin is chemically related to warfarin, a prescription blood thinner, though it isn't the same compound and hasn't been shown to thin blood the way that medication does. Cinnamon and medications: what to check covers what's actually documented.

How do you take a cinnamon supplement?

Follow whatever label is on the product in front of you — dose and form vary enough between products that there's no single instruction that applies to all of them. Cinnamon dosage and when to take cinnamon cover what's actually been tested.

Is a cinnamon supplement the same as ground cinnamon from a grocery store?

It can be — a lot of bark-powder capsules are essentially the same ground cassia or Ceylon bark sold as a spice, just measured into a capsule instead of a shaker. A concentrated extract is a different, more processed product.

Related reading: cinnamon benefits, cinnamon dosage, and how to choose a good cinnamon.