Lectins are widespread in nature, and many foods contain the proteins. Some lectins can be harmful if poorly cooked or consumed in great quantities. They are most potent when raw as boiling, stewing or soaking in water for several hours can render most lectins inactive. Cooking raw beans at low heat,  though, such as in a slow cooker, will not remove all the lectins.
Some studies have found that lectins may interfere with absorption of some minerals, such as calcium, iron, phosphorus, and zinc. The binding of lectins to cells in the digestive tract may disrupt the breakdown and absorption of some nutrients, and as they bind to cells for long periods of time, some theories hold that they may play a role in certain inflammatory conditions such as rheumatoid arthritis and type 1 diabetes, but research supporting claims of long-term health effects in humans is limited and most existing studies have focused on developing countries where malnutrition may be a factor, or dietary choices are otherwise limited.