Most Americans consider cinnamon a simple flavoring, but in traditional Chinese medicine, it's one of the oldest remedies, prescribed for everything from diarrhea and chills to influenza and parasitic worms. Cinnamon comes from the bark of a small Southeast Asian evergreen tree and is available as an oil, extract, or dried powder. It's closely related to cassia ( C. cassia ) and contains many of the same components, but the bark and oils from C. zeyleanicum are thought to have a better flavor.

What Is Cinnamon Used for Today?

Based on the results of one preliminary double-blind, placebo-controlled study, cinnamon has been widely advertised as an effective treatment for type 2 diabetes as well as high cholesterol . However, as described below, this conclusion was premature.

Germany's Commission E approves cinnamon for improving appetite and relieving indigestion ; however, these uses are not backed by reliable scientific evidence. 1

Two animal studies weakly suggest that an extract of cinnamon bark taken orally may help prevent stomach ulcers . 2,3

Preliminary results from test tube and animal studies suggest that cinnamon oil and cinnamon extract have antifungal, antibacterial, and antiparasitic properties. 4-10 For example, cinnamon has been found to be active against Candida albicans , the fungus responsible for vaginal yeast infections and thrush (oral yeast infection), Helicobacter pylori (the bacteria that causes stomach ulcers), and even head lice. However, it's a long way from studies of this type to actual proof of effectiveness. Until cinnamon is tested in double-blind human trials, we can't conclude that it can successfully treat these or any other infections. (For why double-blind studies are so important, see Why Does This Database Rely on Double-blind Studies? )

What is the Scientific Evidence for Cinnamon?

Based on previous animal studies that had suggested potential benefits of cinnamon for diabetes , 11,12 researchers in Pakistan performed a double-blind, placebo-controlled trial in people. 19 In this 40-day study, 60 people with type 2 diabetes were given cinnamon at a dose of 1, 3, or 6 g daily. The results reportedly indicated that use of cinnamon improved blood sugar levels by 18%-29%, total cholesterol by 12%-26%, LDL (“bad”) cholesterol by 7%-27%, and triglycerides by 23%-30%. These results were said to be statistically significant as compared to the beginning of the study and to the placebo group.

However, this study has some odd features. The most important is that it found no significant difference in benefit between the various doses of cinnamon. This is called lack of a dose-related effect, and it generally casts doubt on the results of a study. The researchers counter that perhaps even 1 g of cinnamon is sufficient to produce the maximum cholesterol-lowering effect, and therefore, higher doses simply didn’t add any further benefit. There is another problem with this study as well: no improvements were seen in the placebo group. This too is unusual, and also casts doubt on the results.

In an attempt to replicate these results, a group of Dutch researchers performed a carefully designed 6-week double-blind, placebo-controlled study of 25 people with diabetes. 20 All participants were given 1.5 g of cinnamon daily. The results failed to show any detectible effect on blood sugar, insulin sensitivity, or cholesterol profile. Although this second study was smaller than the first because it had fewer groups ("arms"), overall, its statistical validity is similar. Furthermore, a double-blind study performed in Thailand enrolling 60 people, again using 1.5 g of cinnamon daily, also failed to find benefit. 24 On the other hand, a double-blind study of 79 people that used 3 g instead of 1.5 g daily did find that cinnamon improved blood sugar levels. 21 In addition, a small study involving 22 prediabetic patients with metabolic syndrome found that an extract containing 500 mg cinnamon given once daily was effective at modestly reducing fasting blood sugar and systolic blood pressure, and increasing lean body weight. However, the low dosage of cinnamon used in this study raises concerns about the reliability of these results. 26 Another, very small study evaluated cinnamon for improving blood sugar control in women with polycystic ovary disease , and it too found evidence of benefit. 22

The bottom line: At present, it would be premature to consider cinnamon an evidence-based treatment for type 2 diabetes or high cholesterol, but it has definitely shown some promise.

Regarding type 1 diabetes, a study of 72 adolescents failed to find benefit with cinnamon taken at a dose of 1 g daily. 23

A meta-analysis (formal statistical review) of all published evidence concluded that, thus far, cinnamon has not yet been shown to have any effect on blood sugar levels in people with diabetes. 25

The bottom line: The evidence regarding cinnamon as a treatment for diabetes is highly inconsistent, suggesting that if cinnamon is indeed effective, its benefits are minimal at most.

Dosage

Typical recommended dosages of ground cinnamon bark are 1 to 4 g daily. Cinnamon oil is generally used at a dose of 0.05 to 0.2 g daily. 13

Safety Issues

As a widely used food spice, ground cinnamon bark is believed to be safe. However, cinnamon's essential oil is much more concentrated than the powdered bark commonly used for baking. There is some evidence that high doses of cinnamon oil might depress the central nervous system. 14 Germany's Commission E recommends that pregnant women should avoid taking cinnamon oil or high doses of the bark. 15 Maximum safe doses in young children, nursing women, or individuals with severe liver or kidney disease have not been determined.

When used topically, cinnamon bark oil may cause flushing and a burning sensation. 16 Some people have reported strong burning sensations or mouth ulcers after chewing cinnamon-flavored gum or candy. 17,18 However, these reactions disappeared within days of discontinuing the gum.