FoodsHerbs & spicesBlood sugar
Cinnamon is one of the most-studied culinary spices for metabolic health. The effect is modest and inconsistent — and there’s an important safety twist depending on which cinnamon you buy.
Key takeaways
- Meta-analyses show cinnamon can modestly lower fasting blood glucose in type 2 diabetes, though results are inconsistent.1
- Cassia cinnamon (the common supermarket type) is high in coumarin, which can stress the liver at high daily intakes.2
- Ceylon (“true”) cinnamon is very low in coumarin — the safer choice for regular, higher use.
- Culinary amounts are fine for everyone; it’s a flavour-first spice, not a diabetes treatment.
What it is
Cinnamon is the bark of Cinnamomum trees. Its aroma comes from cinnamaldehyde, and it carries antioxidant polyphenols. Two main types are sold: cassia (cheaper, stronger) and Ceylon (milder, low-coumarin).
The evidence
Systematic reviews find cinnamon produces a small reduction in fasting glucose (and sometimes lipids) in type 2 diabetes, but the effect is inconsistent and not a substitute for medication or diet.1
Ceylon vs cassia & coumarin
Cassia contains far more coumarin, a compound that can be hepatotoxic in large amounts; a few grams of cassia daily can exceed the safe intake.2 For anything beyond occasional cooking, choose Ceylon.
How to use
Enjoy freely in food. If using it deliberately for blood sugar, pick Ceylon and keep expectations modest.
References
Educational summary, not a prescription.
- Allen RW, et al. Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis. Ann Fam Med 2013. pmc.ncbi.nlm.nih.gov
- Impact of cassia bark consumption on glucose and lipid control in type 2 diabetes (coumarin intake). 2021. pmc.ncbi.nlm.nih.gov
This article summarises nutrition science for education and is not a substitute for individual medical advice.