The Short Answer
✅ For daily supplementation: Ceylon cinnamon (Cinnamomum verum)
⚠️ For occasional cooking: Cassia cinnamon is fine in small amounts
The difference comes down to one key compound: coumarin. Ceylon has trace amounts. Cassia has significant amounts — enough that daily high-dose use can cause real liver damage in susceptible individuals.
What Is Coumarin and Why Does It Matter?
Coumarin is a naturally occurring aromatic compound found in many plants. In cinnamon, it contributes to the warm, spicy scent we associate with the spice. At low levels, it's harmless. At high levels — especially from daily supplementation — it poses hepatotoxic (liver-damaging) risk.
The European Food Safety Authority (EFSA) established a Tolerable Daily Intake (TDI) of 0.1 mg/kg body weight per day. For a 70kg adult, that's just 7mg of coumarin daily. Here's where the two cinnamons diverge dramatically:
| Type | Coumarin (g/100g) | In 1 tsp (2.6g) | Safe daily teaspoons (70kg adult) |
|---|---|---|---|
| Ceylon | 0.017 | 0.44mg | ~16 teaspoons |
| Cassia (Chinese) | 0.31 | 8mg | ~0.9 teaspoons |
| Saigon (Vietnamese) | 6.97 | 181mg | ~0.04 teaspoons |
Sources: Abraham et al., Mol. Nutr. Food Res., 2010; EFSA coumarin data 2008.
What Does the Research Actually Show?
Almost all the positive cinnamon clinical trials — on blood sugar, cholesterol, and inflammation — have used either Ceylon or unspecified "cinnamon extract." The landmark 2003 Khan et al. study in Diabetes Care used Cassia at 1-6g/day and showed significant reductions in fasting blood glucose (18-29%), LDL cholesterol, and triglycerides. However, that trial ran for only 40 days, which is below the threshold where chronic coumarin toxicity becomes a concern.
For long-term daily use, the 2013 Allen et al. meta-analysis in Annals of Family Medicine (n=10 RCTs) confirmed benefits for fasting glucose and HbA1c, but the authors specifically noted that Ceylon's lower coumarin profile makes it preferable for sustained use.
A 2014 German Federal Institute assessment found that people consuming large amounts of cinnamon-flavored foods (Christmas baked goods, oatmeal, etc.) regularly exceeded the EFSA TDI — purely from food, before supplementation. This becomes significant if you're also taking cinnamon capsules.
Flavor & Culinary Differences
Ceylon Cinnamon
- •Light, delicate, mildly sweet
- •Floral notes with hints of clove
- •Thin papery quill with multiple layers
- •Pale tan/beige colour
- •Subtle aroma — won't overpower
- •Ideal for: teas, desserts, supplements
Cassia Cinnamon
- •Bold, intensely spicy and sweet
- •The classic 'cinnamon' most people know
- •Single thick, hard layer of bark
- •Dark reddish-brown
- •Pungent, strong aroma
- •Ideal for: baking, coffee, savory dishes
Who Should Definitely Choose Ceylon?
People with liver conditions
Coumarin is metabolised by the liver. Pre-existing liver disease significantly increases sensitivity.
Those on daily supplementation (>1g/day)
Any dose above ~1g/day of Cassia risks exceeding the EFSA TDI, especially combined with dietary cinnamon.
People taking blood thinners (warfarin)
Coumarin has anticoagulant properties that can potentiate warfarin and increase bleeding risk.
Children and older adults
Lower body weight means lower TDI absolute values. Coumarin sensitivity also increases with age.
Those with Type 2 diabetes using cinnamon therapeutically
Long-term use at therapeutic doses requires Ceylon. Cassia is not appropriate for extended supplementation.
When Is Cassia Acceptable?
Cassia isn't inherently dangerous. The European Food Standards Agency permits it in food. The concern is exclusively about high doses, daily supplementation, and cumulative coumarin exposure. Cassia is perfectly acceptable:
- •Sprinkled on oatmeal or coffee occasionally
- •Used in baking and cooking (amounts are small)
- •In short-term studies or trials (under 4-6 weeks)
- •When budget is a primary constraint and amounts are small
Medical Disclaimer
This article is for educational purposes only. It does not constitute medical advice. If you are taking medications or have a health condition, consult your doctor before supplementing with cinnamon. Read our full Disclaimer.
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