Cinnamon
Cinnamon has promising but mixed evidence for blood sugar support. Ceylon cinnamon is the safer choice for daily supplementation. It also has anti-inflammatory and antimicrobial properties, though evidence in humans remains limited.
Cinnamon is studied primarily for its effects on blood sugar regulation. NCCIH states that some research shows cinnamon may help lower blood sugar in people with diabetes, but study results have been mixed. MSK notes cinnamon has anti-inflammatory and antimicrobial properties. Ceylon cinnamon (Cinnamomum verum) is preferred over cassia cinnamon (Cinnamomum cassia) for long-term supplementation due to lower coumarin content.
Where to get it
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Traditional & historical use
Cinnamon has been used medicinally for over 4,000 years. Ancient Egyptians used it for flavouring and embalming. Traditional Chinese medicine used it for warming the body and improving circulation. Ayurvedic medicine used it for digestive complaints, cold and flu, and blood sugar support. It has been used globally as one of the oldest known spices.
Active compounds & mechanisms
Key compounds: cinnamaldehyde, cinnamic acid, cinnamate esters, procyanidins (type A), eugenol, coumarin (high in cassia cinnamon), linalool, terpenes
Cinnamaldehyde is the primary bioactive compound, responsible for the characteristic aroma and most studied anti-inflammatory effects. It inhibits NF-κB signalling and reduces pro-inflammatory cytokines. Procyanidins (type A polyphenols) may improve insulin sensitivity by activating insulin receptor kinase and GLUT4 translocation, potentially enhancing glucose uptake. Coumarin is present in cassia cinnamon at levels that can be hepatotoxic with prolonged high-dose use; Ceylon cinnamon contains negligible amounts and is safer for daily supplementation.
Research & evidence
Strong support Some support Weak or no supportColours show how well the sources back each point. The reason is next to each one.
Some studies show cinnamon may reduce fasting blood glucose in people with type 2 diabetes.
Mixed evidenceSome support. Results are mixed
Study details
Some research shows that cinnamon may help lower blood sugar, but study results have been mixed.
Source: NCCIH, Cinnamon (Last Updated December 2020), Research Findings View source
Cinnamon may modestly lower total cholesterol and LDL cholesterol.
Mixed evidenceSome support. Results are mixed
Study details
Some meta-analyses suggest cinnamon modestly reduces total cholesterol and LDL; effect sizes are small and not consistent across all studies.
Source: MSK About Herbs, Cinnamon (updated August 2023), Research Findings View source
Cinnamaldehyde inhibits NF-κB and reduces inflammatory markers in vitro.
Limited evidenceSome support. Based on one or a few small trials
Study details
Laboratory studies show cinnamaldehyde has anti-inflammatory effects; human clinical evidence remains limited.
Source: MSK About Herbs, Cinnamon (updated August 2023), Research Findings View source
Long-term high-dose cassia cinnamon consumption may cause liver damage due to coumarin.
Limited evidenceSome support. Reviewers rated the certainty low
Study details
Coumarin in cassia cinnamon at high doses over time has been associated with liver toxicity in animal studies and case reports.
Source: NCCIH, Cinnamon (Last Updated December 2020), Safety View source
Gut health notes
Cinnamon has mild antimicrobial properties that may support gut health by modulating pathogenic bacteria. Animal studies suggest prebiotic-like effects, though human evidence is limited.
Dosage
| Form | Amount |
|---|---|
| Capsule | 250–500 mg of Ceylon cinnamon extract (standardised) 1–2x daily, or 1–6 g of Ceylon cinnamon powder daily; most studies use 1–3 g/day |
| Powder | 1/4 to 1 teaspoon (1–3 g) of Ceylon cinnamon powder per day mixed into food or beverages; do not use cassia cinnamon at these doses long-term |
| Tea | 1 cinnamon stick (Ceylon) steeped in hot water for 10–15 minutes; 1–2 cups daily |
Side effects
Generally safe at food amounts. High-dose cassia cinnamon carries risk of liver damage over time. Monitor blood sugar if you take diabetes medications.
Well documented Reported (case reports, anecdotal or one study) None reportedThe circle shows how well documented an effect is, not how serious it is. A rarely reported effect can still be serious, so always read ‘When to stop’.
| Effect | Frequency | When to stop |
|---|---|---|
| Mouth soresWell documentedListed plainly by NIH, MSK or LiverTox | Not stated | Stop and talk to a doctor if you notice any unexpected or concerning symptoms. |
| Liver damage (cassia only)ReportedCase reports only | Not stated | Stop and talk to a doctor if you notice any unexpected or concerning symptoms. |
| Low blood sugar (hypoglycaemia)Well documentedListed plainly by NIH, MSK or LiverTox | Not stated | Stop and talk to a doctor if you notice any unexpected or concerning symptoms. |
| Allergic reactionsWell documentedListed plainly by NIH, MSK or LiverTox | Not stated | Stop and talk to a doctor if you notice any unexpected or concerning symptoms. |
Safety & interactions
Safety
Ceylon cinnamon consumed in amounts typically found in food is considered safe. NCCIH notes that long-term use of cassia cinnamon at high doses may cause liver damage due to coumarin content. MSK says some people develop contact dermatitis from topical use. NCCIH advises that little is known about the safety of cinnamon during pregnancy and breastfeeding beyond food amounts, so medicinal use should be discussed with a healthcare provider.
Contraindications
Cassia cinnamon should not be taken in large daily doses long-term due to coumarin, which can cause liver damage. Cinnamon may lower blood sugar, making it potentially risky in people with diabetes who are already on blood-sugar-lowering medication — monitor closely. Avoid medicinal cinnamon during pregnancy without healthcare provider advice. If you take diabetes medications, warfarin, or antibiotics, see Drug interactions.
Drug interactions
Cinnamon may lower blood sugar and could have additive effects with diabetes medications, increasing risk of hypoglycaemia. NCCIH notes that if you take medication for diabetes, talk to your health care providers before using cinnamon supplements. Monitor blood sugar closely.
Cassia cinnamon contains coumarin, a compound with blood-thinning properties. Combining cinnamon supplements (especially cassia) with warfarin may increase bleeding risk. MSK advises caution.
Cinnamaldehyde may inhibit CYP2C9 enzyme activity, potentially increasing levels of drugs metabolised by this pathway. Relevant for drugs with narrow therapeutic windows.
Established: stated plainly by an authoritative source. Documented: supported by case reports or trial data. Theoretical: based on mechanism, animal data, or a cautious listing. Always check with your pharmacist or prescriber.
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