Cinnamon

What is cinnamon?

Cinnamon is a spice made from the dried inner bark of Cinnamomum trees. NCCIH explains that there are two main types: Ceylon cinnamon (Cinnamomum verum), often called “true” cinnamon and grown mainly in Sri Lanka, and cassia cinnamon (Cinnamomum aromaticum), which is the type most commonly sold in North America. Cinnamon has a long history in traditional medicine in China, India and Persia, and today it is promoted as a supplement for diabetes and weight loss.

What the research says

Cinnamon is one of the most studied spices for blood sugar, but the results are hard to interpret. NCCIH notes that it is often unclear which species or part of the plant was tested, and the chemistry differs considerably between them. Its overall conclusion is that research does not clearly support cinnamon for any health condition and that it is unclear whether it helps with diabetes or weight loss.

NCCIH’s review of supplements for diabetes adds detail. A 2019 review of 16 studies with 1,098 participants found that cinnamon supplementation reduced fasting blood glucose and insulin resistance in people with prediabetes and type 2 diabetes, but the studies differed in dose, duration and participants. Other reviews found possible effects on blood pressure and blood lipids, with smaller effects in Western countries, in higher-quality studies and in studies lasting longer than two months. In the same fact sheet, NCCIH groups cinnamon with chromium and berberine as supplements with weak evidence of a possible benefit, while stressing that there is no reliable evidence any herbal supplement can control diabetes.

How it’s used in supplements

Blood sugar formulas typically include cinnamon bark powder or extract, often without stating the species or the amount. That matters for two reasons. First, without a dose you cannot compare a product with the amounts used in research. Second, cassia cinnamon contains varying levels of coumarin, a compound that might cause or worsen liver problems. NCCIH says cassia usually does not contain enough coumarin to cause harm, but prolonged use of high-coumarin products could be a concern for people with liver disease.

Cinnamon is likely safe in food amounts, and NCCIH notes that supplemental doses below 6 grams per day do not appear to pose a health risk for most people. Higher amounts can cause digestive upset or allergic reactions. Because cinnamon may lower blood glucose, people taking insulin or other diabetes medicines should talk with their doctor first, since combining herbs with diabetes drugs can cause unwanted effects. Large supplemental amounts are best avoided during pregnancy.