Cinnamon
Summary
Cinnamon is sold for blood sugar. A Cochrane review of 10 trials (577 people) found insufficient evidence, while a meta-analysis of 10 trials in type 2 diabetes found lower fasting glucose and lipids but no change in HbA1c. Trials differ widely. Cassia cinnamon contains coumarin, which has been linked to liver problems.
Key facts
How it works
ProposedAnimal studies suggest cinnamon may improve glycaemic control; how it would act in people has not been established.[3]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| HbA1c and glucose in diabetes | No effect | Grade C | Systematic review · n = 577 · 2012 People with type 1 or type 2 diabetes in 10 trials Form: Cinnamon monopreparations (mainly cassia) · Dose: Mean 2 g/day · Duration: 4–16 weeks No significant difference in HbA1c, insulin or post-meal glucose; the fasting glucose effect was inconclusive. Most trials had high or unclear risk of bias. | 22972104 (opens PubMed)Source [3] |
| Fasting glucose and lipids in type 2 diabetes | Improved | Grade C | Meta-analysis · n = 543 · 2013 Adults with type 2 diabetes in 10 trials Form: Cinnamon (mostly cassia) · Dose: 120 mg to 6 g/day · Duration: 4–18 weeks Fasting glucose fell 24.6 mg/dL, total cholesterol 15.6, LDL 9.4 and triglycerides 29.6 mg/dL versus control, and HDL rose 1.7 mg/dL; HbA1c did not change. | 24019277 (opens PubMed)Source [2] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Cassia cinnamon (Cinnamomum cassia / aromaticum) | Varies | No head-to-head human absorption data in the sources cited here. | Contains coumarin; liver interactions have been reported.[1] | Most diabetes trials |
| Ceylon cinnamon (Cinnamomum verum) | Varies | No head-to-head human absorption data in the sources cited here. | Contains only trace coumarin.[1] | Few trials |
Studied doses
Doses studied in human trials ranged from 120 mg to 6 g of cinnamon per day for 4–18 weeks, with a mean of about 2 g/day in the Cochrane review.[2][3]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Some anticancer medicines and nicotineNIH fact sheetNCCIH notes some components of cinnamon may interact with an anticancer medicine or with nicotine.[1]
Who should be careful
- Liver conditions (cassia)
- Coumarin in cassia cinnamon has been linked to liver problems.[1]
- Breastfeeding
- Little is known about larger amounts of Ceylon or cassia cinnamon while breastfeeding.[1]
- People on diabetes medicines
- Trials were small and inconsistent; changes to diabetes care belong with your clinician.[3]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Frequently asked questions
Does cinnamon lower blood sugar?
One meta-analysis found lower fasting glucose but no HbA1c change; Cochrane judged the evidence insufficient.[2][3]
Cassia or Ceylon?
Most supplements and trials use cassia, which has more coumarin; Ceylon has only trace amounts.[1]
Is cinnamon safe for the liver?
Food amounts are likely safe; NCCIH notes liver interactions with coumarin in cassia.[1]
Sources
- [1]Cinnamon. National Center for Complementary and Integrative Health (NCCIH), 2024. fact-sheet
- [2]Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis.. Ann Fam Med, 2013. meta-analysis
- [3]Cinnamon for diabetes mellitus.. Cochrane Database Syst Rev, 2012. systematic-review
What changed
- First draft. Every PMID checked against NCBI E-utilities (title, journal and year taken from the PubMed record) and each evidence row written from its PubMed abstract; self-reviewed in a separate adversarial pass.