12/05/2021 2 min

Beware of overconsumption of herbal supplements containing coumarin

ANSES recently assessed the risks associated with the coumarin content of certain plants when consumed in food supplements in particular. Coumarin is a natural aromatic compound found in certain plants such as cinnamon. It is used in food as a spice or natural flavouring ingredient. Coumarin can cause liver damage when taken in high doses. To avoid exceeding the tolerable daily intake (TDI) set by EFSA, the Agency recommends keeping coumarin intake through food supplements below 4.8 mg per day for a 60 kg adult. It also advises people with a history of liver disease to avoid consumption of cinnamon-rich foods and food supplements containing coumarin.

Coumarin, a compound found in certain plants in varying levels

A natural aromatic compound, coumarin is used in certain cosmetic and household products (perfumes, air fresheners, etc.) but also in food. Coumarin occurs naturally in certain plants such as cinnamon, tonka bean and sweet clover. The coumarin content in these plants or in their essential oils varies widely. They can also be used in food supplements without any maximum level of coumarin being indicated.

The Agency issued an internal request to assess the dietary exposure of the population to coumarin and the risk of exceeding the tolerable daily intake (TDI).

High consumers of food supplements risk exceeding the TDI

Around 40% of adults and 43% of children are exposed to coumarin through their diet, mainly via the consumption of condiments (herbs, spices), sauces, pastries, cakes and sweet biscuits.

When taken in high doses, coumarin poses a risk of liver toxicity. To limit dietary exposure, EFSA has set a TDI of 0.1 mg/kg of body weight per day. French people exposed to coumarin can reach up to 20% of this TDI, without including the consumption of food supplements. There is therefore a high risk of this TDI being exceeded in high consumers of food supplements containing plants rich in coumarin, such as Chinese cinnamon.

The Agency sets a daily intake limit of coumarin in food supplements

To prevent populations with the highest exposure exceeding the TDI, ANSES recommends keeping coumarin intake via food supplements below 4.8 mg per day for a 60 kg adult. As this value only takes dietary exposure into account, the Agency also stresses the need to estimate the contribution of other routes of exposure to coumarin, in particular from cosmetics, home fragrances and household products.

People with a history of liver disease should avoid consumption of foods rich in cinnamon and food supplements with a high coumarin content

Cinnamon essential oils, used in food supplements in particular, were responsible for most of the adverse effects (16 cases out of the 28 that could be analysed), such as liver and digestive symptoms, recorded by the Nutrivigilance scheme. The entire population is advised to pay close attention to the conditions of use of these products, such as the dose or frequency. To ensure safe use by consumers, the Agency stresses the need for manufacturers to specify the botanical identity of the cinnamon and other plants used, along with their coumarin content, in the food supplement ingredients.

Lastly, in order to protect the population groups most at risk, the Agency advises anyone with a history of liver disease or taking medication that may cause adverse liver reactions not to consume foods rich in cinnamon, or food supplements containing coumarin.

Important reminders about the consumption of food supplements:

  • health professionals: during consultations, remember to ask your patients if they are taking food supplements and to notify the nutrivigilance scheme of any adverse effects likely to be related to their consumption;
  • individuals: food supplements are not harmless products. For all our advice on their consumption, take a look at our information sheet (PDF).