Cinnamon
Cassia or Ceylon? — coumarin, glycemia, and the dramatic difference between the two cinnamons.
In 1 minute
What does it provide? Cinnamaldehyde, proanthocyanidins, and — in the case of cassia — coumarin. Glycemic and lipid profile support, antimicrobial and antioxidant effects.
How much? In the kitchen, 1–4 g/day (≈ ½–1½ tsp). Ceylon unlimited; for cassia in the long term ≤ 1 g/day due to the EFSA TDI.
When to avoid? Cassia in high doses in liver disease, in coumarin sensitivity, in pregnancy as a high-dose supplement, alongside anticoagulants as a clinical supplement.
Cinnamon is one of the oldest spices in the world: it was already used in ancient Egyptian mummification rites around 2000 BCE, and appears in the Bible as an ingredient of holy anointing oil (Exodus 30:23). Arab traders kept its source secret for centuries — deliberately spreading myths: the classic "cinnamologus" (cinnamon bird) tale, preserved in Herodotus (5th century BCE), tells that unusual birds collect branches from cliffs on the Arabian coast. The real source (Sri Lanka and South India) remained a secret for nearly 2,500 years; 16th-century Portuguese sailors officially discovered it, and the cinnamon trade built immense wealth for Venice, then the Netherlands and England.
The 18th century brought the distinction between the two species: Cinnamomum verum (Ceylon, "true" cinnamon) and Cinnamomum cassia (Chinese, "fragrant" cinnamon). The cheaper cassia overtook Ceylon worldwide in the 20th century — but between 2006–2012, European food safety reviews showed that cassia contains 1000× more coumarin (average 5–12 mg/g), which can be hepatotoxic at high, long-term consumption. The EFSA 2008 TDI of 0.1 mg/kg/day for coumarin has framed the adult safety window ever since. Akilen's 2010 meta-analysis and Cochrane-level follow-ups, however, show that cinnamon supplements provide a clinically moderate, reproducible effect in T2D. **(EFSA, BMC Med 2010)
🔬 Scientific Background
Cinnamon's two key bioactives are cinnamaldehyde (essential oil, antimicrobial, insulin-sensitizing) and proanthocyanidin-A polymers (polyphenols, antioxidant + glycemic modulation). The water-soluble polyphenol fraction (Cinnulin PF) is the favored extract of clinical trials.
The glycemic evidence is moderately strong: according to Akilen 2012's meta-analysis and several Cochrane updates, 1–6 g/day of cinnamon moderately reduces fasting blood glucose (≈ −0.5 mmol/L) and HbA1c in T2D over 8–16 weeks. The effect is small but reproducible, and can be added as an adjunct alongside lifestyle/medication treatment.
Coumarin risk is a specific feature of cassia cinnamon: cassia's coumarin content averages 5–12 mg/g, while in Ceylon cinnamon it is present only in traces. With the EFSA 0.1 mg/kg/day coumarin TDI, a 70 kg adult's long-term daily cassia amount should remain below ~ 1 g. At high doses (often 5–10 g/day for long months), cholestatic hepatitis cases have been documented.
At the microbiome level, cinnamon's polyphenols bring relative increases in Bifidobacterium and Lactobacillus in vitro and in small human pilots; cinnamaldehyde exerts antimicrobial selection.
- + Oatmeal, yogurt, quark: classic glycemic-buffer combination — cinnamon moderates the postprandial glucose rise.
- + Apple, pear (pectin-fiber): synergistic glycemic modulation.
- + Coffee, cacao: polyphenol stack, flavor harmony.
- + Curry spice blend (turmeric, ginger, cumin, cardamom): the classic "garam masala" matrix.
- + Live cultures (yogurt, kefir): cinnamon polyphenol's microbiome-modulating effect is synbiotic.
- + With fat (butter, coconut fat, walnuts): cinnamaldehyde is fat-soluble, bioavailability increases.
- Cassia chronically over 1 g/day: coumarin exceedance per EFSA TDI — switch to Ceylon.
- Diabetic medications + high-dose cinnamon supplement: additive hypoglycemia, monitoring advised.
- Anticoagulants (warfarin, DOAC) + high-dose cassia: coumarin is a structural analogue, theoretical INR-elevating effect — medical supervision.
- Cinnamon essential oil on empty stomach: severe GI irritation — never consume pure essential oil internally.
- For infants in powder form: aspiration/choking hazard — the "cinnamon challenge" internet trend caused fatal accidents.
- Hepatotoxic medications + high-dose cassia chronically: additive hepatic stress.
- Active liver disease, unexplained liver enzyme elevation: cassia to be avoided; Ceylon is safer.
- Pregnancy (high dose): uterine-stimulating potential; culinary amount safe, clinical supplement not.
- Alongside anticoagulant therapy: only with medical supervision.
- Severe hypoglycemia predisposition: monitoring.
- Active gastric ulcer: high-dose extract may irritate.
- Cinnamaldehyde allergy (contact oral irritation, "cheilitis"): important also before chewing gum/mouthwash.
- Infant, small child: never in dry powder form.
- Planned surgery within 2 weeks: stop high-dose supplement.
Daily serving
½–1½ tsp (1–4 g) Ceylon cinnamon unlimited; cassia in the long term ≤ 1 g/day (children ≤ 0.3 g).
Preparation pattern
- Whole stick: in hot drink, in compote, 5–10 min steeping — essential oil dissolves well.
- Powder: sprinkle toward the end of cooking, don't cook long.
- Marinades: powdered cinnamon + olive oil + lemon — fat increases bioavailability.
Classic patterns
Breakfast oatmeal: oats + water/milk + ½ tsp cinnamon + grated apple + walnut — glycemic buffer.
Garam masala: cinnamon + cardamom + clove + cumin + pepper — Indian base spice.
Mulled wine: red wine + cinnamon stick + clove + orange peel — winter classic.
Moroccan tagine: lamb + cinnamon + ginger + plum — savory-sweet Mediterranean.
Storage and what to avoid
Storage: whole stick 2 years airtight, in dark place; ground powder 6 months. Freshly ground aroma is dramatically stronger.
What not to do: don't swallow dry (cinnamon challenge), don't give chronically in high doses to children's diet as cassia, don't arbitrarily combine clinical-dose supplements with warfarin.
References
[1] EFSA Panel on Food Additives. Coumarin in flavourings and other food ingredients with flavouring properties. EFSA Journal 2008;6(10):793.
[2] Akilen R et al. Cinnamon in glycaemic control: systematic review and meta-analysis. Clin Nutr 2012;31(5):609–615.
[3] Allen RW et al. Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis. Ann Fam Med 2013;11(5):452–459.
[4] Khan A et al. Cinnamon improves glucose and lipids of people with type 2 diabetes. Diabetes Care 2003;26(12):3215–3218.
[5] BfR (German Federal Institute for Risk Assessment). High daily intakes of cinnamon: health risk cannot be ruled out. BfR Opinion 2006.
[6] Ranasinghe P et al. Medicinal properties of "true" cinnamon (Cinnamomum zeylanicum): a systematic review. BMC Complement Altern Med 2013;13:275.
[7] EMA/HMPC. European Union herbal monograph on Cinnamomum verum. 2011.
[8] Lu T et al. Cinnamon polyphenol extract and gut microbiota modulation. Food Funct 2021.