Reviewed by the Scan Dose Research Team and Clinical Advisory Board
Cinnamon
MODERATE EVIDENCESupplementLast updated April 2026
SCAN DOSE SUMMARY
Cinnamon (Cinnamomum cassia and Cinnamomum verum/Ceylon) has moderate evidence for modest blood sugar reduction in type 2 diabetes — roughly 10-25 mg/dL fasting glucose reduction. Our research distinguishes between cassia (common, contains coumarin — liver toxic at high doses) and Ceylon (safer, less studied). The blood sugar effect is real but small and won't replace medication.
Cassia cinnamon contains coumarin compounds; may interact
Hepatotoxic drugsModerate
Coumarin in cassia is hepatotoxic at high doses; additive liver stress
CYP2A6 substratesMinor
Coumarin is metabolized via CYP2A6; competition possible
SAFETY PROFILE
Drug Interactions
⚠️ Coumarin Toxicity (Cassia vs Ceylon)
Cassia cinnamon (most common type sold) contains 1-10mg coumarin per gram. The European Food Safety Authority tolerable daily intake is 0.1mg/kg. For a 70kg adult, that's 7mg — easily exceeded with 2-3g of cassia cinnamon daily. Chronic coumarin exposure causes hepatotoxicity (PMID: 20024932). Ceylon (true) cinnamon contains negligible coumarin (<0.01mg/g) and is safe at higher doses.
Pregnancy & Lactation
Culinary amounts safe. Avoid supplemental doses — cassia coumarin may be teratogenic at high doses.
WADA Status
Not Prohibited
HOW SCAN DOSE SCORES THIS
Ceylon cinnamon products score higher than cassia for long-term use (coumarin safety)
Products not specifying species (cassia vs Ceylon): flag as potential coumarin risk
Diabetes medication users: automatic interaction flag
Products >2g/day cassia: liver toxicity warning
Cinnulin PF: branded extract with removal of coumarin — scores well
CLINICAL REFERENCES
1.
Allen RW et al. Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis.