Pyrrolizidine Alkaloids In Food: What You Should Know

Photo: CC0 / pixabay / matthiasboeckel

Pyrrolizidine alkaloids are substances that plants use to protect themselves. But they can cause problems in what are actually healthy foods. Read here why this is and what you can do.

Pyrrolizidine alkaloids, the poisonous protection in plants

The pyrrolizidine alkaloids (PA for short) are among the phytochemicals. Plants produce these substances to protect them from predators. This makes them incompatible with humans and animals. The medicine portal DocCheck indicates that pyrrolizidine alkaloids can damage the liver. They are also suspected of being carcinogenic and influencing the genetic make-up.

The Consumer advice center names some native plants that protect themselves with the harmful pyrrolizidine alkaloids:

  • Borage
  • Wasserdost
  • Spotted lungwort
  • Comfrey
  • Butterbur
  • Coltsfoot
  • Groundsel or Ragwort

According to the Federal Office for Risk Assessment (BfR) can also be found in some kitchen herbs like oregano and Lovage Pyrrolizidine alkaloids occur.

Pyrrolizidine alkaloids in food

Honey bees fly to flowers whose pollen contains pyrrolizidine alkaloids.
Honey bees fly to flowers whose pollen contains pyrrolizidine alkaloids.
(Photo: CC0 / pixabay / kie-ker)

Pyrrolizidine alkaloids that accidentally get into food are problematic. In foods in which PA should not actually be found, studies sometimes reveal contamination by the plant substance. Since you neither see nor taste PA, you cannot always consciously avoid it.

According to BfR there are always questionable dosages of PA in food, for example in herbal tea, Rooibos tea, Herbs and spices. The consumer center names other foods that can be contaminated with pyrrolizidine alkaloids, such as honey and pollen products or food supplements. Among other things, there are means that Johannis herbs which itself does not form any pyrrolizidine alkaloids.

Pollution with harmful pyrrolizidine alkaloids can have several causes:

  • During harvest: Plants that protect themselves with pyrrolizidine alkaloids grow in meadows or on the edge of fields. When the crops are harvested, they can get into the further production process of the food and contaminate it.
  • confusion: The BfR reports about ready-made salads that may contain plant parts containing PA. For example, the leaves of arugula and ragwort look very similar. Samples of lamb’s lettuce and frisee were also contaminated.
  • By bees: The BfR explains that bees also collect pollen from PA-containing plants. The honey can be contaminated with the poisonous plant substances.

Pyrrolizidine Alkaloids: That’s How Harmful They Can Be

Food containing St. John's wort can be contaminated with pyrrolizidine alkaloids.
Food containing St. John’s wort can be contaminated with pyrrolizidine alkaloids.
(Photo: CC0 / pixabay / manfredrichter)

The chemical compounds of the pyrrolizidine alkaloids are complex and have many different forms.

The German Pharmacist Newspaper reports that over 300 different plants with pyrrolizidine alkaloids are currently researched through studies. However, projections from these studies suggest that it affects around 6,000 plants in total. Not all of the pyrrolizidine alkaloids are equally harmful. However, certain structural features, such as a 1,2 double bond in the molecular structure, have a negative effect on the liver.

The BfR therefore specifically refers in his remarks to pyrrolizidine alkaloids with such a structure. The experts see a probable risk of chronic damage if low doses of PA get into the organism over a longer period of time. This can happen if you regularly drink herbal teas contaminated with PAs. The BfR considers acute poisoning to be rather unlikely with a normal diet, because you would have to be exposed to higher doses for this. There are not yet any reliable limit values ​​for pyrrolizidine alkaloids within the EU.

  • Organ damage: The PAs can initially imperceptibly damage the liver and later cause chronic problems. In addition to the liver, the lungs can also be damaged by PA.
  • Carcinogenic: Medical tests allow the conclusion that 1,2 unsaturated pyrrolizidine alkaloids can change the genetic material and cause cancer.

How to avoid pyrrolizidine alkaloids in food

Coltsfoot contains pyrrolizidine alkaloids.
Coltsfoot contains pyrrolizidine alkaloids.
(Photo: CC0 / pixabay / Hans)

In order to reduce the exposure to pyrrolizidine alkaloids in food, this must be taken into account when harvesting. The Alimentarius Commission the WHO published instructions on how to keep fields as free as possible from weeds containing PAs. The measures are intended to keep the cultivation, harvest and seeds pure, if possible without chemical agents such as Herbicides.

The BfR reports that teas, spices and herbs should be checked for additives containing PA. Since the first examination of herbal teas in 2015, the values ​​have improved. Another Risk assessment 2020 found that the exposure to teas decreased overall.

The consumer advice center advises to look on the packaging for a notice whether the product has been checked for pyrrolizidine alkaloids. Otherwise you have the possibility to inquire at the manufacturing company. There is not yet a standard for such consumer information. Incidentally, even organic farming is no guarantee that the tea does not contain any impurities.

You can protect yourself most effectively with a varied diet. This will avoid eating PA-contaminated foods for long periods of time.

The BfR advises, for example:

  • Drink different teas over and over again. Children should also drink a fruit spritzer or water in between.
  • Watch out for salads, leafy vegetables and Culinary herbs make sure that there are no foreign parts of the plant. Better to sort out generously if something is unknown to you. This also applies if you grow herbs yourself or Collect wild herbs: Only put plants on the table that you are sure to recognize.

The Federal Ministry of Nutrition adds that especially pregnant women and while breastfeeding should not only drink herbal tea.


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