An overview on pyrrolizidine alkaloids: the risks for human health

Natural substances and health do not always go hand in hand. Such is the case with pyrrolizidine alkaloids (PA), a group of alkaloids derived from pyrrolizidine that includes compounds highly toxic to humans. Let’s find out more about them. 

What are pyrrolizidine alkaloids and where to find them?

Pyrrolizidine alkaloids are produced by plants to defend themselves against pests and herbivores and have been identified in about 6,000 botanical species. They are mainly found in some families of the Boraginaceae, Asteraceae, Orchidaceae, and Leguminosae, but also in the Convolvulaceae and Poaceae and in at least one species of the Lamiaceae. It is estimated that 3% of flowering plants worldwide contain these substances

PAs known as 1,2-unsaturated PAs are potential genotoxic carcinogens, i.e. they can cause DNA damage in the long term. They are also suspected of high acute and chronic hepatotoxicity. The danger of pyrrolizidine alkaloids is not a recent discovery: cases of liver toxicity due to ingestion of plants such as Senecio, Heliotrope, and Crotalaria have been documented since the 1920s. 

Apart from isolated cases, the danger becomes more extensive due to the phenomenon of contamination. Many PAs are produced by infesting plants: they grow and flower together with cultivated plants and are difficult to identify and separate once harvested. 

The greatest risks are for high consumers of tea, herbal infusions, and honey, but also animal feed can be contaminated. Pyrrolizidine alkaloids can reach these foods through wild herbs or pollen, in the case of honey. 

The EFSA risk assessment of pyrrolizidine alkaloids

While it is true that humans have always been exposed to such substances through their diet, PAs have been kept under observation by EFSA experts in recent years. In 2011, an initial scientific opinion assessed the health impact of pyrrolizidine alkaloids in food and feed. A health concern was highlighted for heavy consumers of honey, the only food for which data on PA levels were available. 

Assessments have continued over the years, leading in 2017 to an update that takes into account the presence of these toxins also in tea, herbal infusions, and food supplements. Exposure to PAs in these foods represents a potential health threat, particularly to high consumers of tea and herbal infusions, especially in younger segments of the population. The researchers established a new reference point of 237 μg/kg body weight per day to assess the carcinogenic risks posed by pyrrolizidine alkaloids. 

Compared to 2011, 17 new pyrrolizidine alkaloids have been identified in food and feed which need to be further monitored, while studies on the toxicity and carcinogenicity of the most common PAs continue. 

How to prevent pyrrolizidine alkaloid contamination

The presence of pyrrolizidine alkaloids in food products can be minimized or prevented by applying good agricultural and harvesting practices. Hand-harvesting, for example, is a very useful practice to identify and eliminate PA-producing weeds in crops, but can hardly be applied on a large scale. 

As a preventive measure, EFSA has set a maximum level in foods containing significant levels of pyrrolizidine alkaloids. For a complete overview, please refer to the Annex to Commission Regulation (EU) 2020/2040 of 11 December 2020

A transitional period has also been set for products placed on the market before 1 July 2022, which can remain on the market until 31 December 2023. 

Pyrrolizidine alkaloids: EPO’s actions

As a manufacturer of botanical extracts, since 2016 EPO has taken steps to verify the risks associated with our raw materials, considering for each product the part of the plant used, the harvesting method, and the geographic origin. In this way, we were able to identify the level of risk and define appropriate measures and monitoring actions

We have shared this information with our suppliers, actively collaborating with them, and with our customers; we regularly update our product data sheets in light of new developments in the regulatory framework. Our Quality Assurance & Regulatory Affairs team is available for any clarification. 

We believe that research and efforts for a more controlled and responsible supply chain are essential to protect everyone’s health, from pyrrolizidine alkaloids but not only. 

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