Antinutritive effects of wheat-germ agglutinin and other N-acetylglucosamine-specific lectins

Abstract

Incorporation of N-acetylglucosamine-specific agglutinins from wheat germ (Triticum aestivurn ; WGA), thorn apple (Datuva stvarnoniurn) or nettle (Uvtica dioica) rhizomes in the diet at the level of 7 g/kg reduced the apparent digestibility and utilization of dietary proteins and the growth of rats, with WGA being the most damaging. As a result of their binding and endocytosis by the epithelial cells of the small intestine, all three lectins were growth factors for the gut and interfered with its metabolism and function to varying degrees. WGA was particularly effective; it induced extensive polyamine-dependent hyperplastic and hypertrophic growth of the small bowel by increasing its content of proteins, RNA and DNA. Furthermore, an appreciable portion of the endocytosed WGA was transported across the gut wall into the systemic circulation, where it was deposited in the walls of the blood and lymphatic vessels. WGA also induced the hypertrophic growth of the pancreas and caused thymus atrophy. Although the transfer of the gene of WGA into crop plants has been advocated to increase their insect resistance, as the presence of this lectin in the diet may harm higher animals at the concentrations required to be effective against most pests, its use in plants as natural insecticide is not without health risks for man.

Criteria for Safe Use of Plant Ingredients in Diets for Aquacultured Fish

“…In other animals, soybean or other plant lectins have also been reported to cause hyperplastic growth of intes ajiri et Pusztai et al, 1990;Bardocz et al, 1992 andBanwell et a 1993); decreased cell turnover time (Pusztai et al, 1990); uptake of lectin via endocytosis intestinal epithelial cells (Pusztai et al, 1981;Banwell et al, 1984;King et al, 1986;Bardoc et al, 1995); changes in pancreatic weight and enzyme secretion (Greer and Pusztai, 1985;Huisman et al, 1990;Banwell et al, 1993;Pusztai et al, 1993a;Grant et al, 1997); changes in liver weight (Oliveira et al, 1988;Aletor, 1989); reduced plasma insulin levels (Knott et al, 1992;Bardocz et al, 1996;Pusztai et al, 1998); increased cholecystokinin (CCK) release (Jordinson et al, 1996 and; and reduced skeletal muscle mass (Oliveira et al, 1988;Bardocz et al, 1992).…”

Wheat germ supplement reduces cyst and trophozoite passage in people with giardiasis.

“…11 At very high concentrations, several of these lectins have antinutritive effects, with altered gastrointestinal morphology and malabsorption. 11,23 The precise dose of WGA delivered in the current study was unknown but may have been as high as ϳ 60 mg per day. Although Lorernzsonn and Olsen 24 have reported that even larger doses of purified WGA (200 mg per day) can be ingested for short periods of time without ill effect, a detailed evaluation of possible malabsorption was not performed.…”

Lectins as Plant Defense Proteins

“…109, 1995 turb the normal function of the intestine. In addition, some cause systemic effects such as an enlargement of the pancreas (Pusztai et al, 1993). These lectins may also play a role in the defense against predators.…”