Plant-Based Food Supplements Contain High Levels of Cancer Causing Agents

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While many consumers equal 'natural' with 'safe', botanicals and botanical preparations such as plant-based food supplements may contain compounds, like the so called alkenylbenzenes, that are of concern for human health. At high doses these chemical compounds can cause liver cancer in experimental animals. A new study, published in the last issue of the journal Food and Nutrition Sciences, reveals that in many plant-based food supplements levels of these compounds are so low that they are of no concern. Although there are also plant-based food supplements on the market that contain alkenylbenzenes at levels comparable to those causing tumours in laboratory animals. This indicates a need for better regulation and quality control of plant-based food supplements containing alkenylbenzenes.

Botanicals and botanical preparations such as plant-based food supplements are extensively used by consumers within the European Union and the market volume for these products is expanding. In order to assess the safety of plant-based food supplements used in the European Union, an extensive selection and analysis of botanical compounds of concern and present in plant-based food supplements was performed by researchers of Wageningen University, part of Wageningen UR, the University of Milan (Università degli Studi di Milano) and Proform SA collaborating under the EU project PlantLIBRA.

The researchers selected thirty botanical compounds that are of possible concern for human health because they are able to damage the genetic material and/or are carcinogenic. The majority of these compounds were found to belong to the group of the alkenylbenzenes or the group of pyrrolizidine alkaloids. For these botanical ingredients regulatory authorities are aware of the possible risk for human health and consequently the use of pyrrolizidine alkaloid-containing botanicals in food and plant-based food supplements is prohibited in most EU Member States for precautionary health protection reasons. The use of the alkenylbenzenes estragole, methyleugenol, safrole or β-asarone as flavouring agents in food is also banned within the EU. However, restrictions have not (yet) been made with regard to the presence of alkenylbenzenes in plant-based food supplements.

The analysis of several plant-based food supplements containing as main ingredient basil, fennel, nutmeg, sassafras, cinnamon or calamus or their essential oils revealed that some of these products contain relatively high levels of alkenylbenzenes. The researchers concluded that the use of such plant-based food supplements raises a concern for human health and might be of high priority for risk management actions to be taken.

The research team passes the remark that there are also plant-based food supplements in which the levels of the alkenylbenzenes were so low that they are of no concern. Furthermore, they underline that the results obtained in studies in which liver cancer was observed in experimental animals, are based on experiments in which high concentrations of the pure alkenylbenzenes were given to animals instead of administering the plant-based food supplements as such in combination with normal feed. The results obtained in those studies may present an overestimation of the effects compared to those of the alkenylbenzenes in the presence of other ingredients that can be found in the plant-based food supplements or in the normal food. Due to the presence of such a botanical or food pattern, the toxicity of the alkenylbenzenes might be reduced, diminishing the possible risk for human health.

Future studies will place special focus on this subject. However, for the time being it is concluded that some -- although not all -- plant-based food supplements containing the alkenylbenzenes estragole, methyleugenol, safrole or β-asarone might raise a concern for human health and that this indicates a need for better regulation and quality control of plant-based food supplements containing these alkenylbenzenes.