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Hazardous food supplements from natural sources

22/2018, 14.06.2018

Borage, coltsfoot, hemp agrimony: food supplements containing herbs may also contain harmful pyrrolizidine alkaloids

They are one of nature's sophisticated weapons. Plants produce pyrrolizidine alkaloids (PAs) to keep herbivores at bay. The problem: These secondary plant ingredients can also damage the human liver and have been shown to cause genotoxic and carcinogenic effects in animal studies. They can enter the food chain via PA-producing wild herbs growing on areas for cultivated plants. A further problem are food supplements made from plants like borage, coltsfoot or hemp agrimony - all of which produce PAs. "The data available to the German Federal Institute for Risk Assessment show that food supplements containing PA-producing plants or parts of plants can make a significant contribution to the intake of pyrrolizidine alkaloids", says Professor Dr. Dr. Andreas Hensel, President of the German Federal Institute for Risk Assessment (BfR). "In some food supplements, the level is so high that toxic effects are possible even following short-term intake."

Based on new scientific information from the European Food Safety Authority (EFSA) regarding the evaluation of toxicological data, the BfR has updated its risk assessment of PAs in foods. The new assessment takes account of the intake of PAs from all important food groups. Food supplements containing parts or extracts from PA-producing plants have been again demonstrated to be a particular source of PAs for consumers as such supplements had the highest concentrations of PAs.

The highest PA concentration was found in a capsule of a food supplement containing hemp agrimony (Eupatorium cannabinum) as ingredient. Hemp agrimony belongs to the family of composite plants and produces PAs. Other examples of PA-producing plants in food supplements are coltsfoot, comfrey, borage, lungwort, gromwell and butterbur. Supplements containing St. John's wort were also found to be contaminated with PAs in virtually every tested sample. As St. John's wort is not known to be a PA-producing plant, it is likely that the measured PAs are the result of contamination with other wild herbs.

PAs were found in over half of the analysed food supplement samples, and the PA levels varied. In the case of food supplements with high PA levels, the PA intake can be much higher than that resulting from foods for daily consumption. Consequently, food supplements can play a significant role for the PA intake in the case of both short-term and long-term use. The BfR and EFSA both conclude that the consumption of certain food supplements based on PA-producing plants can result in the occurrence of acute toxic effects. In addition to not providing any validated health benefit, the consumption of food supplements of this type poses potential health risks due to the genotoxic and carcinogenic properties of PAs. The BfR therefore advises against the use of food supplements that contain plants or parts of plants that produce PAs. In contrast, no PAs were found in oil-based extracts of PA-producing plants.

With regard to all the relevant food groups, the BfR continues to recommend measures to reduce the concentration of these plant substances in foods. In order to reduce health risks, the BfR advises consumers to heed the general recommendations for variety and diversity when choosing foods.

About the BfR

The Federal Institute for Risk Assessment (BfR) is a scientifically independent institution within the portfolio of the Federal Ministry of Food and Agriculture (BMEL) in Germany. It advises the Federal Government and Federal Laender on questions of food, chemical and product safety. The BfR conducts its own research on topics that are closely linked to its assessment tasks.

The BfR is 15 years old. To mark the occasion, the Institute has published a jubilee brochure which can be downloaded or ordered free of charge at

This text version is a translation of the original German text which is the only legally binding version.



Date Title Size
BfR Opinion No 026/2020
Updated risk assessment on levels of 1,2-unsaturated pyrrolizidine alkaloids (PAs) in foods 1016.0 KB


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