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Coumarin: why the cinnamon you buy matters

Two different barks are sold as cinnamon. Cassia — Cinnamomum cassia and its relatives — is the cheap, dark, strongly flavoured one that fills most supermarket jars. Ceylon cinnamon, Cinnamomum verum, is paler, more brittle and more expensive. The difference that matters for health is coumarin, and cassia has a lot of it.

General information, not a diagnosis. The tolerable daily intake is a lifetime average with a safety margin built in, so exceeding it on a baking day is not a health event; regularly high intake is the concern, especially for children, whose smaller body weight makes the same spoonful a larger dose. If you take a cinnamon supplement, tell your doctor, particularly if you have liver disease or take other medicines. Coumarin is not an anticoagulant and this page is not about warfarin.

The number, and why a per-spoon figure would be misleading

The European Food Safety Authority established a tolerable daily intake for coumarin of 0.1 mg per kilogram of body weight per day — which works out at 6 mg a day for a 60 kg adult and rather less for a child. That figure is well established, it is based on liver effects seen in sensitive individuals, and it is a lifetime daily average with a safety factor already applied. A single day above it is not a health event; a habit of being above it is what the value is designed to prevent.

What this page will not do is tell you how many milligrams are in your teaspoon. Published analyses of cassia coumarin content vary by a wide margin between batches, origins and species within the cassia group, and a single number quoted as though it applied to your jar would be false precision on a question where precision matters. The honest version is the shape: cassia can carry enough coumarin that a few grams a day approaches the tolerable intake for a small adult, and considerably less does so for a child.

Germany’s federal risk assessment institute raised this publicly in the context of Christmas baking, where cinnamon stars and similar products are eaten by children in quantity over a few weeks, and the resulting attention is why Ceylon cinnamon became easy to find in European shops.

Telling cassia from Ceylon

Price is the fastest signal: Ceylon costs several times more, and anything cheap is cassia. The botanical name is the reliable one, and Ceylon cinnamon is usually labelled Cinnamomum verum or Cinnamomum zeylanicum, sometimes as “true cinnamon”. In stick form the difference is visible — Ceylon quills are made of many thin, brittle, papery layers rolled together like a cigar, while cassia is one thick, hard, hollow curl of bark that resists breaking.

Ground, the two are hard to distinguish by eye, which is why the label is the answer. Ceylon is lighter and more tan; cassia is redder and darker. Flavour differs too: Ceylon is more delicate and citrusy, cassia is hotter and more assertive, which is exactly why cassia dominates in baking.

The practical position: for occasional use in cooking, either is fine. For someone who eats cinnamon daily — in porridge, in coffee, as a supplement — or for children eating a lot of cinnamon baking, switching to Ceylon removes the question entirely at the cost of a few euros.

Two things coumarin is not

It is not warfarin. Warfarin is a synthetic 4-hydroxycoumarin derivative, and the anticoagulant activity comes from that specific modification and from what happens when the compound is metabolised by spoiled sweet clover. Dietary coumarin is not an anticoagulant and does not thin blood. The historical connection is real — warfarin was discovered from mouldy sweet clover poisoning cattle — but the compound on your porridge is not the drug.

And it is not the reason to take cinnamon supplements. Cinnamon has been studied for blood glucose and lipids, and the results have been inconsistent, with small and short trials, varied preparations and no established clinical role. If cinnamon is being taken in supplement doses for a medical purpose, the coumarin exposure is a real consideration and the benefit is not established — a poor trade, and worth mentioning to whoever manages your diabetes care.

Coumarin also appears in tonka bean, which is restricted or banned as a food ingredient in several jurisdictions, in sweet woodruff, and in some herbal teas. It has a distinctive sweet, hay-like, vanilla-adjacent smell, which is why it was historically used as a flavouring before the liver effects were characterised.

Coumarin by food group

Bands, not decimals. Where a published quantity for a specific food could not be verified against a document, this surface prints the band rather than a number — and every food below links to its own nutrition page so you can see what else is in it.

What changes the number

• Species is the whole variable: Ceylon carries very little coumarin, cassia carries a lot.
• Batch and origin vary widely within cassia, which is why no single per-spoon figure is trustworthy.
• Body weight sets the tolerable intake, so the same spoonful is a much bigger dose for a child.
• Baking does not destroy it — coumarin survives oven temperatures.
• Supplement doses are far above culinary use, which is where the exposure question becomes real.

Talking to someone who can actually test

Nothing on this surface is personal medical advice. If a food genuinely makes you ill, if you have had a kidney stone or a gout attack, or if you are considering removing a food group from your diet, the person to talk to is your doctor, pharmacist or a registered dietitian — they can test for the things that can be tested for, which a table cannot.

Sources: European Food Safety Authority — opinion establishing the tolerable daily intake for coumarin of 0.1 mg per kg body weight per day. · German Federal Institute for Risk Assessment (BfR) — public assessments of coumarin exposure from cassia cinnamon, including in seasonal baking. · Analytical surveys reporting the wide variation in coumarin content between cassia batches and origins, and the very low content of Cinnamomum verum. · Food names and links: the site food database. Checked 2026-09-06.

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