page_title: Lectin
section_title: Dietary lectin
hierarchical_section_title: Lectin / Dietary lectin
caption_attribution_description: English: Made using PyMol from PDB file 1FAT.
context_page_description: Lectins are carbohydrate-binding proteins that are highly specific for sugar groups of other molecules and so cause agglutination of particular cells or precipitation of glycoconjugates and polysaccharides. Lectins have a role in recognition on the cellular and molecular level and play numerous roles in biological recognition phenomena involving cells, carbohydrates, and proteins. Lectins also mediate attachment and binding of bacteria, viruses, and fungi to their intended targets.
  Lectins are ubiquitous in nature and are found in many foods. Some foods, such as beans and grains, need to be cooked or fermented to reduce lectin content. Some lectins are beneficial, such as CLEC11A, which promotes bone growth, while others may be powerful toxins such as ricin.
  Lectins may be disabled by specific mono- and oligosaccharides, which bind to ingested lectins from grains, legumes, nightshade plants, and dairy; binding can prevent their attachment to the carbohydrates within the cell membrane. The selectivity of lectins means that they are useful for analyzing blood type, and they have been researched for potential use in genetically engineered crops to transfer pest resistance.
context_section_description: Lectins are ubiquitous in nature and many foods contain the proteins. Some lectins can be harmful if poorly cooked or consumed in great quantities. Lectins are most potent when raw: boiling, stewing or soaking in water for several hours can render most lectins inactive. But cooking raw beans at low heat, such as in a slow cooker, will not remove all the lectins. Nevertheless, the longest-lived, healthiest people in the world tend to subsist largely on plant-based diets, which often includes lectins in abundance.
  Some people have proposed "lectin-free" diets, mostly based on the writing of Steven Gundry. A typical lectin-free diet excludes a range of foods, including most grains, pulses, and legumes, as well as eggs, seafood, and many staple fruits and vegetables. However, Gundry's claims are considered pseudoscience, and his book 'cites' studies that either have nothing to do with lectins or even shows that avoiding wheat, barley and rye lead to less beneficial bacteria and more harmful bacteria, contrary to his recommendations! More seriously, Gundry has a conflict of interest, because he sells supplements that purportedly protects against effects of lectins. In one infomercial that lasted almost an hour, he pronounced that supplies are running low, and told viewers to act immediately and order as much as they could store. The necessity of supplements is similarly the crucial argument of his book, in which he writes "Getting all of the nutrients you need simply cannot be done without supplements."
  Some studies have found that lectins may interfere with absorption of some minerals like calcium, iron, phosphorus and zinc. The binding of lectins to cells in the digestive tract may disrupt the breakdown and absorptions 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 like rheumatoid arthritis and Type 1 diabetes. However, 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.
caption: Leucoagglutinin is a toxic phytohemagglutinin found in raw Vicia faba (fava bean).
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