Cinnamon
Also known as: Cinnamomum cassia, Ceylon cinnamon, Cinnamomum verum, Cinnamaldehyde
The blood-sugar spice with a coumarin catch — modest glucose effects, and cassia vs Ceylon matters.
In short
Cinnamon is a spice with genuine, if modest, metabolic credentials: meta-analyses of randomized trials find that cinnamon (typically cassia) lowers fasting blood glucose by a small amount — roughly the effect of a weak add-on therapy, not a replacement for medication. The catch is coumarin: cassia cinnamon, the supermarket default, contains a liver-toxic compound that limits how much you should consume, while Ceylon ('true') cinnamon has negligible coumarin. For most people cinnamon is a flavor with a bonus; for blood-sugar support it is a small, safe addition to — never a substitute for — standard care.
- Trials show small reductions in fasting blood glucose
- Cassia cinnamon contains coumarin, a liver toxin at high intake
- Ceylon cinnamon has negligible coumarin — safer for daily use
- Effects are real but small; not a diabetes treatment
What is Cinnamon?
Cinnamon occupies a rare niche: a pantry spice with enough clinical data to fill meta-analyses. The findings have settled into a predictable shape — small, statistically significant improvements in fasting glucose and lipids, occasionally contradicted by null trials, and never dramatic enough to displace medication. The decision for supplement users is less about whether and more about which: cassia is cheap and abundant but carries a coumarin ceiling, while Ceylon costs more and sidesteps the problem entirely.
Where it comes from
Natural sources
- Inner bark of Cinnamomum trees, dried into quills or ground
- Cassia (C. cassia) — the common supermarket cinnamon, stronger flavor, high coumarin
- Ceylon (C. verum) — 'true cinnamon', lighter flavor, negligible coumarin
How it's made
Supplements use powdered bark or extracts, sometimes standardized to polyphenols or cinnamaldehyde.
What it does in products
Benefits
Blood glucose
moderate evidenceMeta-analyses find cinnamon reduces fasting glucose by roughly 3–10 mg/dL and HbA1c modestly in people with type 2 diabetes or prediabetes — helpful as an adjunct, insufficient alone.
Lipids
moderate evidenceTrials show small improvements in total and LDL cholesterol and triglycerides; effect sizes are modest and inconsistent.
Antioxidant and anti-inflammatory activity
moderate evidenceCinnamon polyphenols measurably increase blood antioxidant capacity; long-term disease outcomes remain unproven.
Side effects & safety
Safety considerations
- Culinary amounts are safe in pregnancy; concentrated supplements are not recommended without medical advice.
- May add to blood-sugar-lowering effects of diabetes drugs — monitor glucose when adding cinnamon.
- High coumarin intake potentiates warfarin and stresses the liver.
- Not for: Liver disease (avoid high cassia intake)
- Not for: Allergy to cinnamon or balsam of Peru
How it's used
In supplements
Trials most often used 1–6 g of cassia powder daily (about 0.5–2 teaspoons) or 250–500 mg of extract. With cassia, keep daily intake under ~1 teaspoon (2–3 g) to stay within coumarin guidance; choose Ceylon for daily higher use.
Regulatory status
- Dietary supplement and GRAS food spice; no disease-treatment approval.
- GRAS (generally recognized as safe) for food use.
Popular products containing Cinnamon
- Cinnamon Bark 600 mgNOW Foods · Supplement
- Ceylon Cinnamon 1,200 mgSwanson · Supplement
- Ceylon Cinnamon CapsulesNutriFlair · Supplement
Product names and brands are shown for reference and belong to their respective owners.
Cassia vs Ceylon: why the variety matters
The coumarin content of cassia cinnamon is the difference between a spice and a supplement-safety question. Cassia runs roughly 0.2–0.8% coumarin, enough that a couple of teaspoons daily can approach the European tolerable intake, and chronic high intake has produced liver injury in case reports. Ceylon contains about a thousandth as much, making it the right choice for anyone consuming cinnamon daily by the spoonful. The trade-off is flavor and price: cassia is the bold 'cinnamon' most Americans know; Ceylon is sweeter, subtler, and more expensive. For occasional cooking, cassia is fine; for daily supplement use, Ceylon is the safer default.
Frequently asked questions
Does cinnamon really lower blood sugar?
The effect is real but small — meta-analyses put the average fasting-glucose drop in single digits. It can support, but not replace, diet, exercise, and prescribed diabetes care.
How much cinnamon is safe per day?
For cassia, about 0.5–1 teaspoon (2–3 g) daily stays within coumarin guidance for most adults. Ceylon has negligible coumarin, so daily culinary amounts are not a concern.
Which cinnamon is best for diabetes support?
Ceylon is the safer choice for daily use because of its negligible coumarin content. Most blood-sugar trials used cassia, so evidence applies mainly to cassia — but the compounds overlap substantially.
The bottom line
Cinnamon offers a small, well-documented nudge on blood sugar and lipids — worth adding to a metabolic health routine, never replacing medication. If you take it daily, make it Ceylon and keep cassia to culinary doses.
References
- Cinnamon. NCCIH (National Institutes of Health). https://www.nccih.nih.gov/health/cinnamon
- Cinnamon and blood glucose — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=cinnamon+blood+glucose+meta-analysis
- Cinnamon, coumarin, and liver — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=cinnamon+coumarin+liver
- Cinnamaldehyde compound summary. PubChem (National Library of Medicine). https://pubchem.ncbi.nlm.nih.gov/compound/637511