Wheat Lectins, Soybean Lectins, and the GI Tract

Here is an interesting piece of research highlighted by David of Healthy Diets and Science. (David's site is fun to browse around in). The study is titled "Lectin-Based Food Poisoning: A New Mechanism of Protein Toxicity". In this study the researchers find the plant lectins wheat germ agglutinin (WGA) and soybean agglutinin (SGA) can not only inhibit repair of gi cells when damaged, they also can block mucus production that the body uses to lubricate damaged areas. Some interesting highlights:

"Areas of epithelial cell necrosis and even zones of complete epithelial cell denudation are seen in biopsies of the stomach and intestine of mammals and insects fed plant lectins. Indeed, the plant lectin may function as a natural insecticide. Epithelial cell microvilli particularly are affected by lectin exposure..."

"Epithelial cells lining the GI tract in vivo, unlike cells in vitro, are constantly exposed to mechanical stress and, consequently, frequently suffer plasma membrane disruptions. However, cell death is not the only outcome of this type of injury: cells are capable of rapidly repairing and thereby surviving plasma membrane disruptions. One key step of the repair mechanism, reviewed in, is exocytotic. For large disruptions, this exocytotic reaction functions by adding a ‘patch’ of intracellular membrane to plasma membrane surrounding the disruption site."

"Exocytosis, which is required for membrane repair, is likely targeted by this class of toxin: previous studies showed that lectins can inhibit exocytosis, and we show here that, in particular, mucin exocytosis, which is coupled to repair in the cells we have studied, is potently inhibited by lectins. Moreover, we have found (data not shown) that inhibition of repair is rapid in onset (<1 min after addition to cell medium) and rapidly reversed by lectin washoff ."

"Because lectins, based on the damage they do to the lining of the GI tract, and their hypertrophic effect, have been implicated in, respectively, celiac disease and cancer, knowledge of this mechanism may have implications beyond a better understanding of food poisoning."

This post is linked to Grain-Free Tuesdays and Fight Back Fridays.