Two Barks, One Name

The cinnamon in your cupboard is probably not the cinnamon you think it is. Here is how to tell Ceylon from cassia, what each one does for you, and where the sweet stuff can quietly turn on you.

By Madame WhiskersteinWellness Desk, Cat House Meow

Every cinnamon roll, every dusted latte, every holiday candle makes the same quiet promise: this is cinnamon. But “cinnamon” on a label is less a single spice than a family name, and the two branches of that family behave very differently once they are inside a body. One is the pale, papery bark of Cinnamomum verum (also called Cinnamomum zeylanicum), native to Sri Lanka and sold as Ceylon or “true” cinnamon. The other is cassia, a thicker, harder, more fiery bark from several related species grown across China, Indonesia, and Vietnam. Most of what sits in supermarket spice aisles is cassia, sold simply as “ground cinnamon.”

Germany’s food-safety scientists put the difference plainly: there is the mild Ceylon cinnamon from Sri Lanka, and there are the tangier cassia types, which carry more of a compound called coumarin.¹ That one molecule is the whole story of why the two barks are treated so differently by regulators, and why a person who sprinkles a little on toast and a person who spoons it into a morning smoothie every day are living in two very different risk worlds.

How to read a cinnamon stick from the end, as described by German and Austrian food-safety authorities.^2,3

The molecule in the middle: coumarin

Coumarin is a naturally occurring flavor compound with a sweet, hay-like scent. In animal experiments, and in patients who were once given it as a medicine, coumarin was shown to damage the liver in sensitive individuals.² For that reason, the German Federal Institute for Risk Assessment (BfR, from the German Bundesinstitut für Risikobewertung) set a Tolerable Daily Intake (TDI) of 0.1 milligrams (mg) of coumarin per kilogram (kg) of body weight: the amount a person can eat every day for life without appreciable health risk. The European Food Safety Authority (EFSA) arrived at the same number independently.²

Translate that into a spice jar and it gets concrete fast. A 60 kg (about 132 pound) adult reaches the daily limit at roughly 2 grams of cassia cinnamon, a little under a level teaspoon. A small child of 15 kg (about 33 pounds) reaches it at around half a gram.^1,2 The Austrian Agency for Health and Food Safety (AGES, from the German Agentur für Gesundheit und Ernährungssicherheit) turns that into kitchen advice: children should get no more than half a teaspoon of cinnamon a day in their porridge or other dishes.³

A little under a teaspoon of supermarket cassia can use up an adult’s entire daily coumarin allowance. Ceylon, by comparison, carries only trace amounts.

There was once a popular argument that coumarin locked inside cinnamon bark is poorly absorbed and therefore harmless. The BfR tested that directly and rejected it: coumarin from cinnamon is absorbed about as well as the pure compound, so the same limit applies.¹ The good news, in the institute’s own framing, is that briefly going over the limit, say during a week of holiday baking, is not a health risk. The concern is the steady, daily, heavy habit.²

Who is most at risk

Not everyone processes coumarin the same way. A study from Japan examining traditional Kampo herbal medicines that contain cinnamon bark notes that only a few percent of patients treated with coumarin were sensitive to its liver-damaging effect. The suspected reason is genetic: a variant of the liver enzyme cytochrome P450 2A6 (CYP2A6) that breaks coumarin down poorly, pushing it toward a more toxic by-product. That “poor metabolizer” variant is considerably more common in Asian populations than in people of European descent.⁴

What the research actually says about benefits

Cinnamon has a long résumé in traditional medicine. A systematic review from the University of Colombo in Sri Lanka notes that it has been used for respiratory, digestive, and gynecological complaints, and that laboratory and animal studies from around the world have shown a range of effects for Ceylon cinnamon, including antioxidant, anti-inflammatory, antimicrobial, and blood-glucose-lowering activity, along with possible cardiovascular benefits.⁵

Human evidence is thinner, and worth reading carefully. The same Colombo team ran a phase I clinical trial in 30 healthy adults, giving a Ceylon water extract in rising monthly doses of 85, 250, and 500 mg over three months. They judged it safe at those doses, while stressing that well-planned human safety studies are still needed before anyone advocates regular medicinal use.⁶ A 2025 randomized, double-blind, placebo-controlled trial in 150 Sri Lankan adults over 12 weeks found that Ceylon extract lowered low-density lipoprotein (LDL, the “bad”) cholesterol compared with placebo, but not by a statistically significant margin.⁸

So the honest summary is this: Ceylon cinnamon is a promising, well-tolerated spice with real biological activity in the lab, modest and inconsistent effects in people, and a far cleaner safety profile than cassia. It is not a cure. It is a better habit.

The contamination nobody tastes: lead

Coumarin is the risk built into the plant. Lead is the risk that sneaks in through the supply chain, and it can hit either kind of cinnamon. In late 2023, Ecuador’s National Agency for Health Regulation, Control and Surveillance (ARCSA, from the Spanish Agencia Nacional de Regulación, Control y Vigilancia Sanitaria) opened an investigation with United States regulators into fruit purées made with cinnamon that carried high levels of lead, and began inspecting every business using cinnamon in its production chain.⁹

Researchers at the Pontifical Catholic University of Ecuador (PUCE, from the Spanish Pontificia Universidad Católica del Ecuador) tested everyday spices and sauces and found lead in six samples at 3 to 5 milligrams per kilogram, up to 20 times the permitted limit, noting that the problem extended beyond cinnamon.¹⁰ By February 2024, the Ecuadorian independent outlet Primicias reported 468 confirmed, probable, and suspected cases of elevated blood lead in children across 44 US states, with investigators’ leading theory being deliberate adulteration for profit: lead chromate, a bright pigment, adds weight and color to ground spice.¹¹

And a word for the whiskered members of the household

Here is where the Cat House has to be firm. Cinnamon essential oil is on the list of oils that are poisonous to cats, whether they lick it or it touches their skin. Cats have fewer of the liver enzymes needed to break these compounds down, kittens and cats with liver disease are even more vulnerable, and there is no antidote, only fast supportive care from a veterinarian.¹² That means cinnamon diffusers, simmering potpourri, and oil-soaked décor have no business in a home with cats. Ground cinnamon from your kitchen is a far smaller concern than the concentrated oil, but it offers a cat nothing and belongs nowhere near the food bowl.

For the humans: choose Ceylon for anything you eat daily, save cassia for the occasional cinnamon bun, keep the portions small for children, and keep the oils away from the cats. Sweet, spicy, and sensible. That is the Cat House way.

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