Dietary Lectins

Lectins are a large class of carbohydrate-binding proteins found in all forms of life, including the human body.  Dietary lectins are found in all foods, but only about 30% contain them in significant amounts. Humans are vulnerable to the toxicity of these lectins.  Concentrated amounts can cause digestive issues and long-term health problems, including autoimmune disorders. The largest concentrations of lectins are found in grains and the legume family (including beans, soybeans and peanuts),  although dairy, eggs, and plants in the nightshade family (like potatoes) also contain lectins and can be problematic for those individuals with autoimmune or digestive problems.  These small compounds can begin to bio-accumulate in the body not only causing damage to the gut lining, but also negatively impacting hunger signals (meaning that you still may feel hungry after consuming an adequate amount of calories).  It also doesn’t help that these are high glycemic foods (foods that turn into sugar more quickly).

The two classes of lectins that are known to be problematic for human health are prolamins (gluten is a prolamin) and agglutinins (found in wheat germ, kidney beans, and soy).  The agglutinins are able to make our red blood cells clump together (or agglutinate).  Once these proteins enter the body, they interact in a big way with the immune system and typically stimulate inflammation, however the adaptive immune system can also be impacted.

Different Types of  Lectins

Some lectins, like those found in wheat, bind to specific receptor sites in your gut lining and interfere with nutrient absorption across your gut wall and into your blood.  C-reactive protein, a marker of inflammation, is an example of a lectin you have circulating in your body right now. Lectins are also used to determine blood type. They trigger inflammation, stimulate a hyperimmune response, and increase the thickness or “stickiness” of your blood.

The Wheat Lectin

The wheat lectin, in particular, is largely responsible for many ill effects on the human body.  It’s important to remember that all seeds of the grass family (rice, wheat, spelt, rye, etc.) are also high in lectins.  Wheat lectin can potentially damage your health in the multiple ways:

  • Pro-inflammatory – it stimulates pro-inflammatory chemical messengers
  • Immunotoxic – has the potential to bind to and activate white blood cells
  • Neurotoxic – has the ability to pass through your blood-brain barrier and attach to the myelin sheath (protective coating of your nerves).
  • Cardiotoxic – induces platelet aggregation and negatively impacts tissue regeneration and removal of neutrophils (a type of white blood cell that is a very important defense against most types of infections).
  • Cytotoxic (cell toxicity) – may cause programmed cell death (apoptosis).

Barley, rye, and tomatoes contain chitin-binding lectins, which are very similar to wheat lectin and can have the same negative health impact as wheat lectin.

Conclusion

It’s important to note that while these dietary lectins may contribute to health problems, especially in certain individuals, cooking at high temperatures effectively eliminates lectin activity from foods like legumes. Soaking, sprouting and fermenting foods can also eliminate lectins and other anti-nutrients, more so from grains.  In addition, most of these lectin-containing foods are high in vitamins, minerals, fiber, antioxidants and other beneficial compounds. So while people who have digestive problems or autoimmune disorders, as well as those following more of a paleo-type diet, may avoid most dietary lectins, it’s ultimately up to each one of us to choose whether or not we include them in our diets.

 

Photo source:

http://gutcritters.com/small-intestinal-bacterial-overgrowth-part-seven-the-role-of-plant-lectins/