Tea bags cause cancer

Pyrrolizidine alkaloids in foods

What are pyrrolizidine alkaloids?

Pyrrolizidine alkaloids are substances that are formed by plants. So they occur in nature. The plants form the substances for protection so that they are not eaten by animals. However, plants that form PA are usually not used directly as food, but rather grow as weeds between the plants actually grown, such as herbs or lettuce. Especially when machines are used to harvest automatically, they are often harvested at the same time. Sorting out is sometimes difficult when the weeds look similar to the actual crop. The ragwort, for example, looks very similar to arugula.

In which foods do they occur?

By harvesting weeds at the same time, the PAs get into tea, spices and salads. In order to be able to assess the risk that PA-containing plants pose for consumers, the Federal Institute for Risk Assessment (BfR) regularly measures the PA levels in food. Current measurements have shown that rocket, aromatic herbs, pollen, rooibos tea and herbal tea in particular contain high levels of PA. In the case of herbs, high levels of PA were found in borage, cumin, oregano and lovage in particular. High levels of PA were also found in bee pollen. When bees harvest this pollen, the PA end up in the honey.

Compared to the years 2011 to 2015, the PA levels in most foods have decreased. Both the mean levels of PA in the foods examined and the very high levels are now much lower. Especially in green tea, black tea, peppermint, chamomile, herbal and rooibos tea, the amounts of PAs contained have fallen sharply. However, the measured PA levels in spices are still very high.

Food supplements made from pollen or plants containing PA, such as borage or comfrey, can also contain PA.

How much PA is contained in plants depends on many factors. On the one hand, different plants contain different amounts of PA. On the other hand, the amounts of PA in different parts of the plant (such as roots or leaves) can be different.

Are they dangerous?

It is not the PAs themselves that are harmful, but their breakdown products in the liver. Certain PAs can damage the liver in this way. Animal experiments with rats have shown that PAs can also change the genetic material in the cells and trigger the development of cancer cells. It is believed that PAs can also have this effect in the human body.

The BfR has investigated which amounts of PA are usually taken up in Germany. To do this, it used the measurement data of the PA in foods and data on the average consumption of various foods. Based on its estimate, the BfR assesses the quantities of PAs that most children and adults ingest through food as harmless. However, herbs and dietary supplements were not included in this estimate. Thus, the ingested amounts of PA through food can be significantly higher in some people. Especially for people who consume large amounts of PA-containing foods over a longer period of time, as well as for children, breastfeeding and pregnant women, there can be a risk to their health.

Are there legal limits?

In the European Union (EU), the recommendation generally applies to include as few substances as possible that are mutagenic and carcinogenic. Because even small amounts of such substances can be dangerous to health if they are consumed over a long period of time. This also applies to PA.

In December 2020, statutory maximum levels for PA in certain teas, herbs and food supplements were set for the first time in the EU. The limit values ​​apply from July 1, 2022.

What can consumers do?

Consumers who drink a lot of tea or drink a lot of tea should not only drink herbal or rooibos tea, but consciously alternate them with other beverages. It also makes sense to alternate between different types of tea and manufacturers. Organic products are no better because PAs are a natural ingredient in plants and can therefore also be found in organic products. Parents in particular are advised to offer their children not only herbal tea, but also other beverages such as mineral water or thin fruit juice spritzers. Babies should be given boiled tap water or mineral water marked "suitable for the preparation of baby food" to drink. Pregnant and breastfeeding women should also make sure to drink herbal tea and tea alternately with other beverages.

In order to avoid ingesting PA-containing plants with the salad, consumers should be careful when washing and preparing leafy lettuce to sort out plants that look strange. You should only collect wild herbs if you are very familiar with them. Because this can unintentionally harvest plants that contain PA.