Cinnamon

Background

• There are many types of cinnamon. Ceylon cinnamon (Cinnamomum verum), grown primarily in Sri Lanka, is known as “true” cinnamon. Cassia cinnamon (Cinnamomum aromaticum), grown in southeastern Asia, is the most common type sold in North America.
• Used as a spice for thousands of years, cinnamon comes from the bark of various species of cinnamon trees. The leaves, flowers, fruits, and roots of cinnamon trees have also been used in cooking and for medicinal purposes. There are differences in the chemical composition of cinnamon products produced from different species or parts of cinnamon trees.
• Cinnamon has a long history of use in traditional medicine in various parts of the world, including China, India, and Persia (Iran).
• Today, cinnamon is promoted as a dietary supplement for diabetes or for irritable bowel syndrome or other gastrointestinal problems, as well as other conditions. Cassia cinnamon is promoted for topical use (application to the skin) as an insect repellent.

How Much Do We Know?

• There have been many studies of cinnamon, especially for diabetes. However, the results of the studies are difficult to interpret because it’s often unclear what type of cinnamon and what part of the plant were used.

What Have We Learned?

• Studies done in people don’t clearly support using cinnamon for any health condition.
• A 2019 review of 18 studies of cinnamon supplementation in people with diabetes suggested that cinnamon could reduce blood sugar but didn’t have a significant effect on hemoglobin A1C, which reflects blood sugar levels over a longer period of time. However, it’s unclear whether these findings are meaningful because 10 of the studies didn’t identify the type of cinnamon used, and 8 of the studies were judged to be of low quality for other reasons.
• It’s uncertain whether cinnamon is helpful for weight loss or for controlling blood levels of cholesterol and related lipids. There’s not enough evidence to show whether cinnamon is helpful for irritable bowel syndrome.
• It’s unclear whether cassia cinnamon is effective as an insect repellent.

What Do We Know About Safety?

• Cinnamon supplements appear to be safe when consumed in the amounts commonly used in foods as a spice or flavoring agent. Use in larger amounts or for long periods of time is sometimes associated with side effects, most commonly gastrointestinal problems or allergic reactions.
• Cassia cinnamon contains a chemical called coumarin, which can be harmful to the liver. Some cassia cinnamon products contain high levels of this substance. In most cases, consuming cassia cinnamon doesn’t provide enough coumarin to cause significant problems. However, prolonged use of cassia cinnamon could be an issue for sensitive people, such as those with liver disease.
• Little is known about whether it’s safe to use cassia cinnamon during pregnancy or while breastfeeding. Ceylon cinnamon may be unsafe for use during pregnancy if consumed in amounts greater than those commonly found in foods. Little is known about whether it’s safe to use Ceylon cinnamon during breastfeeding in amounts greater than those commonly found in foods.
• Cinnamon should not be used in place of conventional medical care or to delay seeking care if you have health problems. This is particularly true if you have diabetes.

Keep in Mind

• Take charge of your health—talk with your health care providers about any complementary health approaches you use. Together, you can make shared, well-informed decisions.

For More Information

• Using Dietary Supplements Wisely
• Know the Science: How Medications and Supplements Can Interact
• Know the Science: How To Make Sense of a Scientific Journal Article

Key References