Nothing like legumes: They contribute to sugar balance, reduce the chance of heart disease, help reduce blood pressure, and contain many nutrients such as protein and dietary fiber that contribute to the digestive system and general health.If you have recently eaten legumes, such as lentils or beans for example, and then felt abdominal pain or bloating, it may be because of the components found in them called “lectins”.

What are lectins?

lectins (Lectins) are a large family of proteins that bind carbohydrates to them. They are present in many foods, animal and plant foods. Plants produce them mainly as defense mechanisms against insects, molds, fungi and diseases.
In plants alone, over 500 different types of lectins have been identified – some are safe to eat, while others can cause health problems. The reasons for the differences are the type of carbohydrate that binds to the protein and the amount of lectins.

What foods have lectins?

Lectins can be found in many foods such as: fruits, vegetables, nuts, seeds and fish, but these are small amounts. On the other hand, legumes, such as lentils and black, red and white beans, as well as grains (mainly wheat); contain large and significant amounts of lectins.

What happens when you consume foods that contain them?

Lectins do not undergo breakdown in the digestive system, and most of them do not pose a health risk at all. However, some of them can bind to the cell walls in the small intestine and cause abdominal pain, bloating, diarrhea and vomiting. This can explain why the consumption of legumes, for example, can cause many people severe stomach pains. Of course, the duration of cooking, the way of cooking and the amount eaten affect the onset of pain and their intensity. In addition, lectins impair the absorption of important nutrients, which has earned them the dubious nickname “anti-nutrients”.

Is it dangerous?


Beyond the absorption problems and stomach pains mentioned, consumption of fresh legumes can be dangerous. The reason is called lectin toxicity Phaseolus vulgaris (or in short, PHA) caused by consumption of fresh red beans. In the 80s of the last century, 50 cases of suspected food poisoning resulting from the consumption of fresh or improperly cooked red beans were reported. From 2004 to 2013, over 7,000 people in China were reported to have been affected by insufficient cooking of this bean.

Is it possible to reduce the amount of lectins in food?


Although lectins cannot be broken down by our digestive enzymes, they are broken down quite easily by heat of at least 100 degrees. Studies indicate different recommendations for cooking them, such as boiling for 5-10 minutes, half an hour or an hour. A 2018 study found that boiling legumes for an hour (at 95 degrees) resulted in a 93% to 99.8% reduction in the amount of lectins. By the way, in case you were wondering – using a microwave alone is not effective for breaking down lectins and may even be dangerous.

Are there benefits to lectins?


In recent years, certain studies indicate that lectin may have therapeutic benefits. Because they can bind carbohydrates well, there is great interest in their potential as a diagnostic tool and as a cancer treatment tool for example. In addition, lectins affect the colon bacteria, the immune system and the inflammation in the body – not necessarily in a negative way. However, more studies are needed to shed light on these aspects.


Bottom line:
 A diet rich in plant foods may contribute to the prevention and reduction of many chronic diseases such as: cardiovascular diseases, cancer, stroke, dementia, cataracts and diabetes. However, it should be remembered that plant foods may also contain components that can harm health, such as the lectins mentioned in this article. If you consume legumes containing this component, it is better that you soak them for several hours and then boil them for at least half an hour to an hour, in order to significantly reduce the amount of lectins in them. This way you will also reduce the chance of suffering from stomach pains and other side effects in the digestive system.The author is Amir Winograd, a clinical dietitian with a master’s degree in public health

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