The joint announcement from the Federal Institute for Medicinal Products and MedicalDevices (BfArM) and the Federal Institute for Risk Assessment (BfR) states their opinion that products marketed with a diabetes health claim should be classified as medicinal products and required to seek marketing authorisation.
During the marketing authorisation procedure the efficacy, safety and pharmaceutical quality of a medicinal product are examined.
As it stands currently, food supplements and dietetic foods are not required to obtain marketing authorisation, which means, said the BfR and the BfArM, that no examination of their quality, efficacy, safety or scientific risk-benefit analysis is undertaken.
But concerns about differing coumarin levels in some products, said to cause liver damage and inflammation when higher doses are taken over a longer period by sensitive individuals, have spurred the institutes into action.
"The cassia cinnamon used in food supplements and dietetic foods - particularly cinnamon powder products - sometimes contains high levels of coumarin," said the BfR and the BfArM in a joint statement.
"Some of the cinnamon products examined contained so much coumarin that the recommended daily dose would already exceed the tolerable daily intake (TDI) of 0.1 milligram coumarin per kilogram body weight.
"BfArM and BfR believe that the regular taking of large amounts of cinnamon in the gram range, something that is recommended to diabetics by the general press and seemingly even by some doctors, is harmful," they state.
The courts have now classified cinnamon-containing dietetic foods carrying the health claims as 'medicinal products'. They cannot, therefore, be marketed as foods. However, cinnamon-containing "food supplements" sold without any health claims will not be affected.
"Diabetics who ingest large amounts of cinnamon powder or cinnamon products daily on the advice of a few doctors of as part of a diet plan should not take these products because of the possibly high coumarin contents and the inadequately proven efficacy," said Professor Reinhard Kurth, director of BfArM, in a statement.
The institutes said that ingestion of coumarin from other sources like cinnamon-containing foods and cosmetics, damage to health cannot be ruled out from the long-term taking of products with a high cassia cinnamon content.
"Consumers who ingest large amounts of cassia cinnamon powder or cassia cinnamon products for other reasons, for instance to improve digestion, should not take these products either," said Professor Andreas Hensel, BfR's president.
Not all cinnamon capsules contain such harmful products, however. Indeed, researchers at the USDA have performed significant research into a water-extract of cinnamon, marketed as Cinnulin PF, by Integrity Nutraceuticals International.
According to Integrity, Cinnulin PF contains standardized quantities of the active components of cinnamon, two trimers and one tetramer classified as double-linked type-A polymers, but not the potentially harmful compounds.
Cinnulin PF is claimed to be the only cinnamon extract standardized for these compounds.