Cinnamon bark is used to make powders, capsules, teas, and liquid extracts. Although there are many kinds of cinnamon, Ceylon cinnamon (sometimes referred to as “true” cinnamon) and cassia cinnamon (also known as Chinese cinnamon) are the most familiar.
What the science says
High-quality clinical evidence (i.e., studies in people) to support the use of cinnamon for any medical condition is generally lacking.
An analysis of five clinical trials concluded that cinnamon does not appear to affect factors related to diabetes and heart disease.
Side effects and cautions
Cinnamon appears to be safe for most people when taken by mouth in amounts up to 6 grams daily for 6 weeks or less. Some people may have allergic reactions to cinnamon or its parts.
Cassia cinnamon contains coumarin, the parent compound of warfarin, a medication used to keep blood from clotting. Due to concerns about the possible effects of coumarin, in 2006, the German Federal Institute for Risk Assessment warned against consuming large amounts of cassia cinnamon.
Cinnamon should not be used in place of conventional medical care or to delay seeking care if you are experiencing symptoms that are of concern; this is particularly true if you have diabetes.
Tell all your health care providers about any complementary health approaches you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.
Source: “Herbs at a Glance: Cinnamon.” National Center for Complementary and Alternative Medicine. https://nccih.nih.gov/health/cinnamon.