The Infamous “A” In Food

Wednesday, May 4th, 2022

By Yip See Chung, SCIEX

Pyrrolizidine alkaloids (PAs) are a group of naturally occurring alkaloids based on the structure of pyrrolizidine. PAs are produced by plants as a defense mechanism against insect herbivores. More than 660 PAs and PA N-oxides have been identified in over 6,000 plants, and about half of them exhibit hepatotoxicity.1 They are frequently found in plants in the BoraginaceaeAsteraceaeOrchidaceae and Fabaceae families. It has been estimated that 3% of the world’s flowering plants contain PAs.2

PAs can be found in food due to contamination by PA-containing plants. Potential sources of exposure are3:

  • Honey and pollen dietary supplements where bees harvest PA-containing plants
  • Salad crops and cereals if contaminated with PA-containing weeds
  • Herbal products, supplements and teas prepared from or contaminated by PA-containing plants
  • Products of animal meat, milk and egg origin if food-producing animals graze on PA-containing plants or consume feed containing PAs

The first recorded incident of PA poisoning in humans was in 1920 in South Africa. Many people in the Western Cape region suffered from cirrhosis of the liver after eating bread made with wheat that was likely contaminated with Senecio burchellii. To date, the largest reported outbreak of human intoxication by PAs was in Afghanistan in 1974, when an estimated 35,000 people were affected by grain contaminated with Heliotropium plant material. Of the 7,200 cases that were examined, 1,600 people were affected and many died 3-9 months after the onset of clinical signs.4

On 27 July 2017, the European Union Authority issued a statement on the risks to human health related to the presence of PAs in honey, tea, herbal infusions and food supplements.5 The CONTAM Panel established a new reference point of 237 μg/kg body weight per day to assess the carcinogenic risks of PAs. The Panel concluded that there is a possible health concern for humans exposed to PAs, particularly for those in the general population who are frequent and high consumers of tea and herbal infusions, and even more so for those in younger population groups.6

As consumer behaviors change and dietary habits turn toward more plant-based choices, there is a growing need for routine testing of plant-based food and commodities. Recently, scientists at SCIEX have developed a sensitive and robust analytical method for the detection and quantification of 54 alkaloids in plant-based food matrices using the QTRAP 6500+ system (Figure 1).7

An accurate and sensitive method for the quantification of 33 pyrrolizidine and 21 tropane alkaloids in plant-based food matrices

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Picture2 Figure 1. Chromatographic separation of 54 alkaloids.


  1. Radominska-Pandya, A (2010). “Invited Speakers”. Drug Metabolism Reviews. 42 (S1): 1–2. doi:3109/03602532.2010.506057PMID 20842800.
  2. Smith, L. W.; Culvenor, C. C. J. (1981). “Plant sources of hepatotoxic pyrrolizidine alkaloids”. J. Nat. Prod. 44 (2): 129–15. doi:1021/np50014a001PMID7017073.
  3. Food Standards Agency, Government of the United Kingdom. Occurrence of Pyrrolizidine Alkaloids in Food. Last updated: 4 February 2020.,%2Fmilk%2Feggs%20%2D%20if%20food
  4. Ali Esmail Al-Snafi, Pharmacological and toxicological effects of Heliotropium Undulatun {H. Bacciferrum} and Heliotripium Europaeum – A Review, Indo American Journal of Pharmaceutical Sciences: 05 pp. 2150-2158 (04)
  5. EFSA CONTAM Panel, 2017. Statement on the risks for human health related to the presence of pyrrolizidine alkaloids in honey, tea, herbal infusions and food supplements. EFSA Journal 2017;15(7):4908, 34 pp.
  6. Commission Regulation (EU) 2020/2040 of 11 December 2020 amending Regulation (EC) No 1881/2006 as regards maximum levels of pyrrolizidine alkaloids in certain foodstuffs. Official Journal of the European Union. December 14, 2020.
  7. Stahl-Zeng J., Steed J., Meltretter J. An accurate and sensitive method for the quantification of 33 pyrrolizidine and 21 tropane alkaloids in plant-based food matrices. SCIEX, 2021 (RUO-MKT-02-12768-A).

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