Sick due to lectins in plant-based foods? It depends on the dose, type and preparation
What it's about:
Whether pulses, vegetables or fruit - many plant-based foods contain lectins. These substances protect plants from diseases and pests. However, they can be harmful to humans. The dose and type of lectin are decisive: most lectins are harmless when consumed in moderation. However, the lectin phasin, which is found in raw pulses, poses a health risk. It agglutinates red blood cells and can lead to gastrointestinal problems. In large quantities, phasin can even be fatal in extreme cases. "The good news is that lectins can be destroyed by heat", says Professor Dr Tanja Schwerdtle, Vice President of the Federal Institute for Risk Assessment (BfRshort forGerman Federal Institute for Risk Assessment). "Therefore, the recommended preparation methods for pulses should always be followed."
As a rule of thumb, fresh pulses should be cooked for at least 30 minutes. Dried pulses such as chickpeas, kidney beans and lentils should be soaked for at least five hours and boiled in fresh water, after pouring away the soaking water. Gentle cooking methods such as steaming are not suitable for most pulses. Sugar snap peas and peas are an exception, as they contain only low amounts of lectins. They can even be eaten raw in moderation. This also applies to many other foods that contain lectins, including tomatoes, certain mushrooms and bananas.
Undesirable effects of lectins mainly occur when pulses are improperly prepared. In modern cooking, for example, pulses are often only cooked gently - this way the vegetables stay crisp and the loss of vitamins is reduced. However, when preparing pulses such as beans, chickpeas or lentils, it is important to ensure that they are heated and cooked sufficiently. For example, the seeds and pods of the green garden bean contain the lectin phasin. After eating a few raw seeds, abdominal pain and nausea often occur. In severe cases, bloody diarrhoea, fever and a drop in blood pressure may occur. Whether symptoms occur and how severe they are varies greatly from person to person. Children are particularly at risk due to their low body weight.
However, it is not a good idea to avoid plant-based foods in favour of a diet low in lectins. A diet with a wide variety of vegetables, fruits and sufficiently cooked pulses provides valuable vitamins, minerals and dietary fibre.
Further information on lectins on the BfRshort forGerman Federal Institute for Risk Assessment website
- Press release “Only enjoy beans cooked” Go to press release
- BfRshort forGerman Federal Institute for Risk Assessment Opinion “Lectins in plant-based foods: Is there a health risk?” Go to opinion