Remedy · root & spice
Cinnamon and blood sugar: what the evidence says
Mixed trial results for blood sugar and no change in long-term HbA1c. Cassia cinnamon, the common supermarket kind, carries coumarin, which limits how much is sensible.
By the editors of Alimentotherapy Last reviewed 3 min read Not medical advice
Cinnamon
Cinnamomum verum and C. cassia
Best-supported use: Blood sugar in type 2 diabetes
The short answer
A Cochrane review of 10 trials found no significant effect of cinnamon on HbA1c, insulin or after-meal glucose in people with diabetes, though a later meta-analysis found lower fasting glucose Leach 2012; Allen 2013. NCCIH says research does not clearly support cinnamon for any health condition, and cassia cinnamon contains coumarin, which can harm the liver in large amounts NCCIH; Abraham 2010.
The evidence, use by use
Each claim graded on human studies only. How we grade
| Use | Grade | What the research found |
|---|---|---|
| Blood sugar in type 2 diabetes | Limited | In 10 trials (543 patients), 120 mg to 6 g a day lowered fasting glucose but did not change HbA1c. A Cochrane review of 10 trials found no significant difference in HbA1c, insulin or after-meal glucose. Allen 2013; Leach 2012 |
| Cholesterol and triglycerides in type 2 diabetes | Limited | The same meta-analysis reported small drops in total and LDL cholesterol and triglycerides, from small trials with very different doses and products. Allen 2013 |
| Weight loss | Not supported | NCCIH says it is unclear whether cinnamon supplementation helps with weight loss, and higher quality research would be needed. NCCIH |
Blood sugar: why the results disagree
The trials were small, short (4 to 18 weeks) and used doses from 120 milligrams to 6 grams a day, mostly of cassia cinnamon Allen 2013; Leach 2012. Cochrane rated the risk of bias high or unclear in all but two trials and concluded there is insufficient evidence to support cinnamon for diabetesLeach 2012. HbA1c, the measure of average blood sugar over months, did not change in either review.
If you take diabetes medicine, do not swap it for cinnamon. For the food patterns with better evidence, see blood sugar.
Cassia, Ceylon and coumarin
Much of the cinnamon sold in supermarkets is cassia, and labels often do not say. Cassia contains coumarin, a natural compound that can damage the liver in sensitive people. European regulators set a tolerable daily intake of 0.1 mg of coumarin per kilogram of body weight, and a German survey found heavy consumers of cassia cinnamon can reach that level from foodAbraham 2010. Ceylon cinnamon contains only trace amounts NCCIH.
In the kitchen
Cinnamon as a spice in normal cooking is fine for nearly everyone. If you use it daily by the spoonful, in smoothies or oatmeal, Ceylon cinnamon is the lower-coumarin choice. Labels often do not say which species they contain.
Safety
Never swallow a spoonful of dry ground cinnamon as a dare. NCCIH warns serious harm is possibleNCCIH.
Before you try it: safety and interactions
Who should avoid it or ask first
- You have liver disease: avoid regular large amounts of cassia cinnamon because of coumarin.
- You take diabetes medicine: talk to your clinician before adding cinnamon supplements, so low blood sugar can be watched for.
- You take any regular medicine and want to use supplements: NCCIH advises asking your provider first.
Possible side effects
- Stomach upset or allergic reactions with large amounts or long use.
- Skin irritation or contact dermatitis from cinnamon oil or powder on the skin.
Pregnancy and breastfeeding
Cinnamon in normal food amounts is considered safe; there is little information on supplement doses in pregnancy or while breastfeeding. NCCIH; Abraham 2010
Medicine interactions
We found no well-documented medicine interactions for cinnamon at food amounts. That is not proof there are none: tell your pharmacist about any herb or supplement you take.
Check another food or medicine in the interactions list.
Common questions
Does cinnamon lower blood sugar?
The evidence is mixed. A 2013 meta-analysis of 10 trials in type 2 diabetes found lower fasting glucose, but neither it nor a Cochrane review found a change in HbA1c, the long-term measure. It is not a substitute for diabetes medicine.
What is the difference between cassia and Ceylon cinnamon?
Cassia, the most common cinnamon in US supermarkets, contains coumarin, which can harm the liver in large amounts; Ceylon cinnamon contains only traces. For daily spoonful use, Ceylon is the lower-coumarin choice.
Sources
Primary research and government sources, each checked on the date this page was reviewed.
- CochraneLeach MJ, Kumar S. Cinnamon for diabetes mellitus. Cochrane Database Syst Rev. 2012. PMID 22972104.
- PubMedAllen RW, et al. Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis. Ann Fam Med. 2013. PMID 24019277.
- PubMedAbraham K, et al. Toxicology and risk assessment of coumarin: focus on human data. Mol Nutr Food Res. 2010. PMID 20024932.
- NCCIHNational Center for Complementary and Integrative Health. Cinnamon: Usefulness and Safety.
Keep reading
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