I wouldn't worry about sprinkling cinnamon on your toddler's oatmeal. Overall, the amounts of cinnamon used in cooking and as flavoring are very safe and good to include in the diet. Just to be sure, I checked with Tieraona Low Dog, M.D., an internationally recognized expert in the fields of integrative medicine, dietary supplements and women's health, and an authority on herbal medicine.
Dr. Low Dog told me that there is some concern about ingesting large amounts of common cassia cinnamon (Cinnamomum cassia) due to the varying levels of coumarin, a blood-thinning phytochemical, it contains. There is little to no coumarin in "true" or Ceylon cinnamon (C. zeylanicum), but Dr. Low Dog told me that it is hard to tell the difference between the two in the marketplace. Too much coumarin in the diet can cause liver damage. However, she agrees that there's no reason to worry about sprinkling cinnamon on a child's oatmeal.
Dr. Low Dog also reminded me that some studies have shown that one to three grams of cinnamon per day (1/4 to 1 teaspoon) can lower blood sugar in people with diabetes. No significant adverse effects have been seen. Cinnamon's effect on blood sugar is believed to be due to a proanthocyanidin, an active ingredient that increases sensitivity of receptors to insulin.
There also have been suggestions that cinnamon can help with cholesterol control. However, the effects seen in studies so far haven't equaled those of better-studied statin drugs. We need more research to determine if cinnamon really can help keep cholesterol in check.
Andrew Weil, M.D.