As we mentioned in another post, when it comes to treating type 2 diabetes, cinnamon most often means Cinnamomum cassia, the bitter, blackish "curry cinnamon" used in Indian cuisine, not the aromatic, reddish "sweet cinnamon" used in baking. There is, however, a potential downside to taking cinnamon if you are getting treatment for blood clots.
Cinnamomum cassia contains detectable concentrations of coumadins. These are chemicals that work in the same way as warfarin, Plavix, Trental, and other medications to help maintain circulation. The herb, however, does not contain large amounts of coumadins.
As is often the case with such matters, the controversy about the coumadins in cassia began in a relatively silly way. Although the spice is not used for baking in
, in 2006 the Bundeinstitut für Arzneimittel (the German equivalent of the US FDA) expressed concern that if it were, it could cause some people problems. Specifically, if you added enough of this kind of cinnamon to cookies that you were sure they tasted bad, then people who ate this kind of cinnamon in baked goods because they prefer bitter cookies to sweet cookies (yeah, right) might then absorb too much of the coumadins. Germany
But let's assume there really are such people. Obviously, the German federal administrators do.
If you allow a 10-fold safety factor, keeping consumption to less than 10% of the amount that could cause problems, the BfürA eventually decided, then a person who weighed at least 50 kilos (110 pounds) could consume 1,000 mg of this kind of cinnamon safely every day, and a person who weighed at least 100 kilos (220 pounds), 2,000 mg.
What all the deliberations left out is that the tastier kind of cinnamon also contains coumadins, in about the same concentration. If the kind of cinnamon that has an effect on type 2 diabetes might interfere with blood clotting, then it happens that the tasty kind of cinnamon (that's usually added to sugary sweets in English-speaking countries, although it's used with savories in Latin America) should be restricted, too. It's not. Apparently something has to be competitive with a medication to merit a cautionary note.
There have been no reports of "cinnamon poisoning" even among people who use up to 6,000 mg a day. We recommend that anyone who is taking any kind of prescription blood thinner avoid cinnamon entirely, and that anyone inform the doctor of taking the herb. It will help the doctor notice unusual patterns of blood clotting should a blood thinner ever be needed. But we certainly recommend that type 2 diabetics avoid cinnamon rolls and cinnamon candies.