Coumarin doesn’t get much attention on a cinnamon label, but it’s the single biggest reason not all cinnamon is safe to use the same way.
It’s a naturally occurring compound found in cinnamon bark, and at high enough intakes, it’s been linked to liver stress. The catch is that how much coumarin you’re actually consuming depends almost entirely on which type of cinnamon you’re using.
Here’s what the regulatory limits are, how the two main types compare, and how to work out whether your own intake is in a reasonable range.
What Is Coumarin?
Coumarin is a naturally occurring aromatic compound found in a range of plants, cinnamon bark among them. The National Center for Complementary and Integrative Health notes that cassia cinnamon in particular contains coumarin, which can be toxic to the liver when consumed in large amounts or over a long period.
It isn’t added to cinnamon deliberately. It’s simply part of the bark’s natural chemistry, and the amount present varies enormously depending on the species.
The Official Safety Limit
The tolerable daily intake (TDI) for coumarin, set by the European Food Safety Authority (EFSA) and confirmed by Germany’s Federal Institute for Risk Assessment (BfR), is 0.1 mg per kilogram of body weight per day.
In practical terms:
- 60 kg (132 lb) adult: about 6 mg of coumarin per day
- 70 kg (154 lb) adult: about 7 mg of coumarin per day
- 80 kg (176 lb) adult: about 8 mg of coumarin per day
This is a conservative long-term safety threshold, not a hard toxic dose. It’s designed to be a level you could consume every day, indefinitely, without expected harm.
Ceylon vs Cassia: The Numbers That Matter
This is where the practical difference becomes clear. Published testing consistently finds a large gap between the two species.
| Cinnamon type | Coumarin content | Source |
|---|---|---|
| Ceylon (Cinnamomum verum) | Below detection limit to ~190 mg/kg | Peer-reviewed retail analysis |
| Cassia (Cinnamomum cassia, various origins) | 700–12,200 mg/kg | Peer-reviewed retail analysis |
A 2012 peer-reviewed analysis of 60 ground cinnamon samples from 12 retail brands found mean coumarin levels of roughly 2,650 to 7,017 mg per kilogram in cassia-derived samples, while a Ceylon sample from Sri Lanka tested in the same study was coumarin-free.
Doing the Math: How Little Cassia It Takes
Using a mid-range figure of about 2,900 mg/kg (2.9 mg per gram) for cassia cinnamon, here’s roughly what it takes to reach the EFSA daily limit for a 70 kg adult (7 mg):
- 7 mg ÷ 2.9 mg/g ≈ 2.4 grams of cassia cinnamon
That’s under a level teaspoon. If you’re using cassia cinnamon in coffee, oatmeal, or baking every day, it’s genuinely easy to approach or exceed the TDI, especially with higher-coumarin batches.
Ceylon cinnamon, by contrast, would require an impractically large amount, often several tablespoons or more, to reach the same coumarin exposure, since its levels are near or below the detection limit in most testing.
Does This Actually Cause Harm?
Most people who occasionally sprinkle cassia cinnamon on food are not at meaningful risk. The concern is specifically tied to regular, concentrated exposure over time, such as daily supplement use or habitual high intake.
There is at least one published case report illustrating the upper end of this risk: researchers documented a 23-year-old who developed hepatitis after consuming 1 to 2 grams of cinnamon daily for two months, an intake estimated at roughly 3.3 to 6.6 mg of coumarin per day at typical cassia concentrations, below the TDI in absolute terms but sustained daily over an extended period.
Separately, a study of patients taking traditional Kampo medicines containing cinnamon bark examined the relationship between total coumarin intake and liver enzyme changes, reinforcing that cumulative daily exposure, not a single dose, is what matters.
These aren’t reasons for alarm with occasional culinary use, but they are a reasonable basis for caution with daily, high-dose cassia supplementation.
Who Should Be Most Careful
- People taking a cinnamon supplement daily, rather than using it occasionally in cooking
- Anyone with a history of liver disease or impaired liver function
- People taking medications metabolized by the liver
- Anyone using concentrated cassia extract capsules rather than culinary-amount powder
For any of these situations, checking the product label for the species, or choosing a Ceylon-labeled supplement, is a simple way to reduce coumarin exposure without giving up the ingredient altogether.
FAQs
Regulatory bodies (EFSA and BfR) set the tolerable daily intake at 0.1 mg per kilogram of body weight, which works out to roughly 6–8 mg per day for most adults.
Based on typical coumarin concentrations, as little as about 2 to 2.5 grams, under a teaspoon, can approach the daily limit for an average adult. Lower-coumarin batches allow for more; higher-coumarin batches allow for less.
Not entirely, but its coumarin levels are so low in most testing that they’re often near or below the detection limit, making it far less of a concern for daily use compared with cassia.
There are documented case reports of liver injury linked to sustained, high-dose cassia cinnamon intake. This appears to be uncommon and tied to regular, concentrated exposure rather than occasional use.
Yes. Coumarin exposure is cumulative across everything you eat in a day, including cassia used in cooking, baked goods, and supplements, not just supplement doses alone.
If you have liver disease, take medications processed by the liver, or plan to use a cassia-based cinnamon supplement long-term, it’s worth discussing with your healthcare provider first.
Sources
- NCCIH — Cinnamon: Usefulness and Safety, National Institutes of Health
- AGES — Coumarin, Austrian Agency for Health and Food Safety, citing EFSA/BfR tolerable daily intake
- Assessment of Coumarin Levels in Ground Cinnamon Available in the Czech Retail Market, Journal of Food Composition and Analysis, via PMC
- Coumarin levels in cassia and Ceylon cinnamon, Journal of Agricultural and Food Chemistry (ACS, 2010)
- The Relation between Hepatotoxicity and Total Coumarin Intake from Traditional Japanese Medicines Containing Cinnamon Bark, PMC
Choosing a Ceylon-labeled supplement is the simplest way to keep coumarin exposure low even with daily use. See our picks for the best Ceylon cinnamon supplements, all selected for low coumarin content and third-party testing.
