Nutritional toxicity of raw kidney beans in pigs. Immunocytochemical and cytopathological studies on the gut and the pancreas

A Review of Bioactive Compound Effects from Primary Legume Protein Sources in Human and Animal Health

The global demand for sustainable and nutritious food sources has catalyzed interest in legumes, known for their rich repertoire of health-promoting compounds. This review delves into the diverse array of bioactive peptides, protein subunits, isoflavones, antinutritional factors, and saponins found in the primary legume protein sources-soybeans, peas, chickpeas, and mung beans. The current state of research on these compounds is critically evaluated, with an emphasis on the potential health benefits, ranging from antioxidant and anticancer properties to the management of chronic diseases such as diabetes and hypertension. The extensively studied soybean is highlighted and the relatively unexplored potential of other legumes is also included, pointing to a significant, underutilized resource for developing health-enhancing foods. The review advocates for future interdisciplinary research to further unravel the mechanisms of action of these bioactive compounds and to explore their synergistic effects. The ultimate goal is to leverage the full spectrum of benefits offered by legumes, not only to advance human health but also to contribute to the sustainability of food systems. By providing a comprehensive overview of the nutraceutical potential of legumes, this manuscript sets a foundation for future investigations aimed at optimizing the use of legumes in the global pursuit of health and nutritional security.

Effect of Raw Chickpea in the Broiler Chicken Diet on Intestinal Histomorphology and Intestinal Microbial Populations

The aim of the study was to determine the effect of partial replacement of SBM protein with CPR-derived protein in the broiler rearing period from 22 to 42 days of age on the intestinal histomorphology and the composition of the intestinal microbial population. Male broiler chicks aged 1 day were assigned to two groups with different nutrition schemes (n = 100 in each, 5 cages of 20 chicks in each). The chickens were reared for 42 days. All birds were fed isonitrogenous and isoenergetic diets: starter (1 to 21 d), grower (22 to 35 d), and finisher (36 to 42 d). From rearing day 22, different diets were provided to the birds: the SBM group received feed with 100% soybean meal protein, and the diet of the CPR group the protein originated from soybean meal was replaced by 50% chickpea protein. The study results indicated a significant impact of the inclusion of CPR in the diet on the basic intestinal structures (thickness of myenteron: submucosa, jejunum and duodenum mucosa, and jejunum transversal lamina). The addition of CPR led to shortening of intestinal villi, an increase in villus thickness, and reduced intestine absorptive surface in the duodenum and jejunum. The CPR group exhibited a significantly lower villus length-to-crypt depth ratio in the jejunum (p < 0.001). The inclusion of chickpeas in the diet increased the total count of mesophilic bacteria and coliforms in the intestinal contents (p < 0.05). In summary, it has been demonstrated that the inclusion of CPR in the diet induced considerable disturbances in metabolism and intestinal structure. Although CPR is a cheap protein source, its use in poultry diet does not ensure development of the intestinal structure comparable to that in the case of an SBM-only diet.

Non-union bone fractures

The human skeleton has remarkable regenerative properties, being one of the few structures in the body that can heal by recreating its normal cellular composition, orientation and mechanical strength. When the healing process of a fractured bone fails owing to inadequate immobilization, failed surgical intervention, insufficient biological response or infection, the outcome after a prolonged period of no healing is defined as non-union. Non-union represents a chronic medical condition not only affecting function but also potentially impacting the individual's psychosocial and economic well-being. This Primer provides the reader with an in-depth understanding of our contemporary knowledge regarding the important features to be considered when faced with non-union. The normal mechanisms involved in bone healing and the factors that disrupt the normal signalling mechanisms are addressed. Epidemiological considerations and advances in the diagnosis and surgical therapy of non-union are highlighted and the need for greater efforts in basic, translational and clinical research are identified.

Regulation of Intestinal Inflammation by Soybean and Soy-Derived Compounds

Environmental factors, particularly diet, are considered central to the pathogenesis of the inflammatory bowel diseases (IBD), Crohn’s disease and ulcerative colitis. In particular, the Westernization of diet, characterized by high intake of animal protein, saturated fat, and refined carbohydrates, has been shown to contribute to the development and progression of IBD. During the last decade, soybean, as well as soy-derived bioactive compounds (e.g., isoflavones, phytosterols, Bowman-Birk inhibitors) have been increasingly investigated because of their anti-inflammatory properties in animal models of IBD. Herein we provide a scoping review of the most studied disease mechanisms associated with disease induction and progression in IBD rodent models after feeding of either the whole food or a bioactive present in soybean.

N-Acetyl-d-galactosamine prevents soya bean agglutinin-induced intestinal barrier dysfunction in intestinal porcine epithelial cells

Soya bean agglutinin (SBA) is a glycoprotein and the main anti-nutritional component in most soya bean feedstuffs. It is mainly a non-fibre carbohydrate-based protein and represents about 10% of soya bean-based anti-nutritional effects. In this study, we sought to determine the effects of N-Acetyl-D-galactosamine (GalNAc or D-GalNAc) on the damage induced by SBA on the membrane permeability and tight junction proteins of piglet intestinal epithelium (IPEC-J2) cells. The IPEC-J2 cells were pre-cultured with 0, 0.125 × 10-4 , 0.25 × 10-4 , 0.5 × 10-4 , 1.0 × 10-4 and 2.0 × 10-4  mmol/L GalNAc at different time period (1, 2, 4 and 8 hr) before being exposed to 0.5 mg/ml SBA for 24 hr. The results indicate that pre-incubation with GalNAc mitigates the mechanical barrier injury as reflected by a significant increase in trans-epithelial electric resistance (TEER) value and a decrease in alkaline phosphatase (ALP) activity in cell culture medium pre-treated with GalNAc before incubation with SBA as both indicate a reduction in cellular membrane permeability. In addition, mRNA levels of the tight junction proteins occludin and claudin-3 were lower in the SBA-treated groups without pre-treatment with GalNAc. The mRNA expression of occludin was reduced by 17.3% and claudin-3 by 42% (p < 0.01). Moreover, the corresponding protein expression levels were lowered by 17.8% and 43.5% (p < 0.05) respectively. However, in the GalNAc pre-treated groups, occludin and claudin-3 mRNAs were reduced by 1.6% (p > 0.05) and 2.7% (p < 0.01), respectively, while the corresponding proteins were reduced by 4.3% and 7.2% (p < 0.05). In conclusion, GalNAc may prevent the effect of SBA on membrane permeability and tight junction proteins on IPEC-J2s.

The influence of dietary replacement of soybean meal with high-tannin faba beans on gut-bone axis and metabolic response in broiler chickens

Faba bean (FB) seeds can be a good protein-energy component in animal feed. However, the presence of anti-nutritional substances is a negative feature of FB seeds. The aim of this study was to examine the influence of different levels of unprocessed FB seeds in feed on the gut-bone axis and metabolic profile in broilers. Ninety six, 1-day-old Ross 308 broiler chickens were randomly selected to one of the 3 dietary treatments (32 chickens in each, divided into 8 pens with 4 birds per each pen): the control group fed standard diet with soybean meal and without FB seeds, group I fed 8/15% (starter/grower) of high-tannin FB seeds, and group II fed 16/22% of high-tannin FB seeds. Bone mechanical examination, hematological and serum biochemical analysis as well histomorphometry of small intestine and liver tissue were performed. The intake of high-tannin FB seeds, irrespective of their amount, did not alter the bone geometric, mechanical and densitometric parameters nor influenced basal hematological parameters, however it resulted in: decreased serum concentration of total cholesterol and calcium; a reduced longitudinal myenteron of small intestine; increased mucosa and villus epithelium thickness, villus length, thickness and absorptive surface in duodenum; increased number of active crypts in jejunum; unchanged collagen area, intercellular space, and total cell number in the liver; decreased number of multinuclear hepatocyte cells. Moreover, the livers of birds fed the higher dose of high-tannin FB seeds had lymphocytic infiltrates in portal tracts and sinusoids. Feeding of unprocessed high-tannin FB seeds exerted an influence on the gastrointestinal tract by increased absorptive surface. In conclusion, the dietary inclusion of unprocessed high-tannin FB seeds had no negative effects on broiler growth, tibial bone mechanical properties and intestinal characteristics. Unprocessed high-tannin FB seeds may be used in broiler diets, but their dietary levels should not be higher than those discussed.

Gut-bone axis response to dietary replacement of soybean meal with raw low-tannin faba bean seeds in broiler chickens

It seems that faba bean (FB) seeds could be a good protein-energy component in animal feed, but the presence of anti-nutritional substances limits their use as a substitute of soybean meal. The aim of the study was to examine the influence of different concentrations of raw, low-tannin, FB seeds on the gut-bone axis in Ross 308 broilers. One-day old chickens were randomly subjected to one of the 3 dietary treatments: the control group was fed standard diet based on soybean meal and without FB seeds, and two groups were fed 8%/15% and 16%/22% of raw low-tannin FB seeds in the starter and grower, respectively. On the 35th day, hematological and serum biochemical analyses as well histomorphometry of the small intestine and liver tissue and bone mechanical tests were performed. The diet type had no effect on the body weight gain and feed conversion ratio. However, the basal intestinal structures were significantly reduced in birds fed the lower concentration of FB. The enlargement of nerve plexuses was dependent on the concentration used in the diet and, additionally, on the kind of plexus and location in the intestinal tract. The liver was characterized by an increase in non-hepatocytes. There was no influence of the low-tannin FB seeds on most of the analyzed serum parameters in the 35-day-old broiler chickens, except the decreased concentration of total cholesterol and Ca in both experimental groups, triglycerides in group I, and P and uric acid in group II. Furthermore, the increasing concentration of the dietary low-tannin FB did not influence the activities of AspAT (except the group fed the higher amount of FB), ALAT, and LDH. The broiler chickens had no visible leg lesions and no problem in the locomotor function, but the tibiae were lighter mainly in birds fed the higher concentration of FB seeds. Geometric analysis revealed reduction of the cross section area and wall thickness, indicating a decline in the bone midshaft, which influenced the densitometric parameters and the results of mechanical tests. In conclusion, the dietary inclusion of raw low-tannin FB seeds had no negative effects on broiler growth, but disturbed the intestine structure and tibia characteristics. Therefore, all these negative effects necessitate additional examinations before inclusion of raw low-tannin FB seed into poultry diet.

New research highlights: Impact of chronic ingestion of white kidney beans (Phaseolus vulgaris L. var. Beldia) on small-intestinal disaccharidase activity in Wistar rats

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Impact of bean exposure on disaccharidase activity in rat jejunum was investigated.

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Raw white beans depressed the jejunal maltase and sucrase activities in Wistar rats.

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No lectins were found in the blood and feces of rats after 10 days of bean feeding.

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White beans may pose a risk to the consumer when eaten raw or undercooked.

The chronic ingestion of raw or undercooked kidney beans (Phaseolus vulgaris L.) is involved in the pathogenesis of multiple organ dysfunction; the underlying mechanisms are still poorly understood. The objective of this study was to assess the gavage effects of a raw Beldia bean variety on the brush border disaccharidase activities in the jejunal mucosa of Wistar rats. Twenty young adult male rats were randomly assigned into 2 groups of 10 rats each: Control, rats were gavaged with 300 mg of a rodent pellet flour suspension (RPFS); Experimental, rats were orogastrically fed a dose of 300 mg Beldia bean flour suspension (BBFS). Prior to determining the disaccharidase activity by Dahlqvist method, the blood and stool specimens were collected on day 10. The sera and feces were screened for the presence of lectins by serologic and hemagglutination assays. The results showed that the brush border maltase and sucrase activities were significantly diminished but lactase activity did not undergo any change in BBFS-gavaged animals as compared with control. Preliminary immunobiochemical assays revealed the absence of lectins in the systemic circulation and feces of rats, but further work is required to prove this. Overall, the dietary administration of BBFS caused depression of the activity of the small intestinal enzymes maltase and sucrase.

Effect of including purified jack bean lectin in casein or hydrolysed casein-based diets on apparent and true ileal amino acid digestibility in the growing pig

The effect of including purified jack bean lectin (concanavalin A) in the diet of grower pigs on endogenous ileal nitrogen (N) and amino acid (AA) losses, and apparent and true ileal AA digestibility was investigated in a study with four growing pigs (average initial live weight (LW) 25 kg) fitted with simple T-cannulae at the terminal ileum. Both the homo-arginine (HA) method and peptide-alimentation method were used to estimate endogenous gut AA losses. The animals were offered four diets :(1) an enzymatically hydrolysed casein (EHC) containing diet, (2) an EHC containing diet supplemented with 266 mg/kg jack bean lectin, (3) a normal casein (NC) containing diet, and (4) a NC containing diet supplemented with 266 mg/kg lectin. For the estimation of ileal endogenous AA flows in pigs given NC diets, a subsample ofNC was guanidinated to convert lysine to HA. The experiment was conducted using a 4X4 Latin-square design. In each experimental period, pigs were adjusted to the experimental diets for 5 days. On day 6, ileal digesta was collected continuously for 24 hfor determination of apparent ileal digestibility. At 08:30 h of day 8 the HA NC diets were offered to pigs on NC treatments and ileal digesta were again collected for 24 h from all pigs. There were no interactive effects of casein type and added dietary lectin on apparent and true ileal AA digestibility and endogenous ileal AA flows (P > 0-05). The addition of lectin to the diet did not influence (P > 0-05) the apparent ileal digestibility of dry matter (DM), crude protein (CP) and AA. Casein type did not affect ileal DM digestibility (P > 0-05). Pigs given the NC-based diets had higher (P < 0-05) apparent ileal AA digestibility than pigs given the EHC-based diets. Addition of lectin to the diet did not influence (P > 0-05) endogenous ileal CP and AA flows. Endogenous ileal AA losses were generally higher (P < 0-05) in pigs given EHC diets than in pigs given NC diets. Neither casein type nor diet lectin level influenced (P > 0-05) the true ileal digestibility ofCP and AA; values ranged for most AA between 0-98 and 1-00. These data suggest that including purified jack bean lectin at the level of 266 mg/kg in a casein-based diet did not influence the ileal endogenous CP and AAflow, nor the apparent and the true ileal digestibility ofCP and AA, in growing pigs between 25 and 50 kg LW. Compared with the HA method, the peptide-alimentation method yielded higher estimates of ileal endogenous CP and AA acid losses in pigs given casein-based diets, although these two methods yielded similar estimates of true ileal AA and CP digestibility.

Effects of soybean agglutinin on mechanical barrier function and tight junction protein expression in intestinal epithelial cells from piglets

In this study, we sought to investigate the role of soybean agglutinin (SBA) in mediating membrane permeability and the mechanical barrier function of intestinal epithelial cells. The IPEC-J2 cells were cultured and treated with 0, 0.5, 1.0, 1.5, 2.0, 2.5, or 3.0 mg/mL SBA. Transepithelial electrical resistance (TEER) and alkaline phosphatase (AP) activity were measured to evaluate membrane permeability. The results showed a significant decrease in TEER values (p < 0.05) in a time- and dose-dependent manner, and a pronounced increase in AP activity (p < 0.05). Cell growth and cell morphology were used to evaluate the cell viability. A significant cell growth inhibition (p < 0.05) and alteration of morphology were observed when the concentration of SBA was increased. The results of western blotting showed that the expression levels of occludin and claudin-3 were decreased by 31% and 64% compared to those of the control, respectively (p < 0.05). In addition, immunofluorescence labeling indicated an obvious decrease in staining of these targets and changes in their localizations. In conclusion, SBA increased the membrane permeability, inhibited the cell viability and reduced the levels of tight junction proteins (occludin and claudin-3), leading to a decrease in mechanical barrier function in intestinal epithelial cells.

Effects of soybean agglutinin on intestinal barrier permeability and tight junction protein expression in weaned piglets

This study was developed to provide further information on the intestinal barrier permeability and the tight junction protein expression in weaned piglets fed with different levels of soybean agglutinin (SBA). Twenty-five weaned crossbred barrows (Duroc × Landrace × Yorkshire) were selected and randomly allotted to five groups, each group with five replicates. The piglets in the control group were not fed with leguminous products. 0.05, 0.1, 0.15 and 0.2% SBA was added to the control diet to form four experimental diets, respectively. After the experimental period of 7 days (for each group), all the piglets were anesthetized with excess procaine and slaughtered. The d-lactic acid in plasma and the Ileal mucosa diamine oxidase (DAO) was analyzed to observe the change in the intestinal permeability. The tight junction proteins occludin and ZO-1 in the jejunum tissue distribution and relative expression were detected by immunohistochemistry and Western Blot. The results illustrated that a high dose of SBA (0.1–0.2%) could increase the intestinal permeability and reduce piglet intestinal epithelial tight junction protein occludin or ZO-1 expression, while low dose of SBA (0.05% of total diet) had no significant affects. The contents of DAO, d-lactic acid, occludin or ZO-1, had a linear relationship with the SBA levels (0–0.2%) in diets. The high dose SBA (0.1–0.2%) could increase the intestinal permeability and reduce piglet intestinal epithelial tight junction protein occludin or ZO-1 expression, while low dose of SBA (0.05% of total diet) had no affects.

Nutritional outcome and immunocompetence in mice fed on a diet containing raw field beans (Vicia faba, var. minor) as the source of protein

Feeding growth mice on diets containing raw field beans (Vicia faba var. minor) as the only source of protein brought about an impairment in growth, muscle mass and liver weight. No changes in food consumption were observed, but the food intake:weight gain ratio was increased in those animals. Plasma protein, triacylglycerols and cholesterol values were not affected by the dietary treatment although serum glucose and zinc levels fell after legume intake as well as the number of circulating erythrocytes. The relative enlargement of thymus and spleen in the legume-fed mice was apparently accompanied by a reduction in the cell number and an increase in cell size, while the protein synthesis capacity followed differentiated patterns in both tissues when assessed through protein, DNA and RNA determinations. The haemagglutination titres and the number of rosette-forming cells were lower in those animals fed on the field bean diet as well as the splenic lymphocyte responses to phytohaemagglutinin, Concanavalin A or lipopolysaccharide mitogens used to evaluate the functional status of T and B lymphocytes. The present study describes, apparently for the first time in mice, the involvement of field bean intake in some immunological disturbances affecting both humoral- and cell-mediated aspects of the immune response.

Pathological effects of Phaseolus vulgaris isolectins on pig jejunal mucosa in organ culture

The interaction of plant lectins with pig small intestinal epithelium in organ culture was studied. The binding of Phaseolus vulgaris (PHA) isolectins E4 and L4 to the microvilli and microvillus vesicles in the top area of the villi was shown by immunoelectron microscopy. Differences were observed in the distribution of the isolectins. In the explants cultured for five hours with the PHA isolectins, the enterocyte height and the villus length were decreased, and a lower villus: crypt ratio was calculated. Ultrastructurally, the microvilli were shorter and irregularly positioned. After incubation with both PHA E4 and PHA L4, clusters of small vesicles, tied off from the microvilli, were seen in higher numbers when compared with control explants. The activity of the brush border enzyme sucrase-isomaltase was reduced in the PHA E4 incubated explants but did not change in the PHA L4 incubated explants. This investigation shows that explants of pig jejunal mucosa in organ culture are suitable for study of the pathological effects of lectins on the small intestinal mucosa. This method may also be used in elucidating the mechanisms by which damage to mucosal structure occurs.

Comparison of growth, nitrogen metabolism and organ weights in piglets and rats fed on diets containing Phaseolus vulgaris beans

The effects of lectins in the diet have been mainly studied in rats. An important question is whether results obtained in rats can be extrapolated to larger animals like the pig. Phaseolus vulgaris beans are rich in toxic lectins. Therefore a study was carried out to compare the effects of diets containing 200 g Phaseolus vulgaris beans (raw or toasted)/kg in rats and piglets. Live-weight gain, nitrogen digestibility and N balance were much lower in piglets than in rats fed on diets containing raw beans. Live-weight gain and N balance were slightly negative in the piglets. When toasted beans were given, live-weight gain and N balance values were reduced in piglets but hardly at all in rats. Giving raw beans caused hypertrophy of the pancreas in the rats but in piglets the weight of the pancreas was reduced. Spleen weight was depressed in the piglets but not in the rats. Weight of liver was not affected in either animal species. When toasted beans were given no effects on the weights of pancreas, spleen or liver were found in piglets or rats. It was concluded that the piglet is much more sensitive to antinutritional factors in the Phaseolus vulgaris bean than the rat.

Effect of variable protein contents in diets containing Phaseolus vulgaris beans on performance, organ weights and blood variables in piglets, rats and chickens

A comparison was made of the effects of antinutritional factors present in Phaseolus vulgaris on piglets, rats and chickens. Also the hypothesis of whether the negative effect on weight gain due to the inclusion of raw Phaseolus vulgaris in the diet can be attributed to an insufficient supply of amino acids was tested. Test diets containing 200 g raw Phaseolus beans/kg were balanced for digestible protein and amino acids; in one diet extra casein was incorporated. The main response criteria were live-weight gain and the weight of various organs including the intestine. Live-weight gain in piglets was markedly reduced during feeding 200 g raw Phaseolus vulgaris/kg in the diet, but not in rats and chickens. Addition of casein did not improve the weight gain of the piglets, indicating that a toxic factor was responsible for the reduced weight gain and not an insufficient supply of amino acids. The weights of the spleen and thymus were markedly reduced in the piglets when the diets with raw Phaseolus beans were given, but not in the rats and chickens. Additional supply of casein did not change this effect. Indications were found that when the supply of dietary protein is adequate there is no reduction in pancreas weight with raw Phaseolus beans as was observed in previous experiments. The weight of the intestine was increased in all three species due to feeding raw Phaseolus vulgaris.

Pathologic changes of the small intestinal mucosa of pigs after feeding Phaseolus vulgaris beans

The jejunal mucosa of pigs fed diets containing Phaseolus vulgaris beans was characterized grossly as mucosal atrophy and microscopically as atrophy and blunting of the villus in association with elongation of crypts with cells with increased mitotic activity. These morphologic findings were most severe in the proximal and middle parts of the jejunum. Compared to controls, goblet cells were significantly decreased in the villus but markedly increased in the crypt region. The activity of aminopeptidase and sucrase-isomaltase in the test animals was also significantly lower than in the controls. The findings in this study suggested that feeding Phaseolus vulgaris beans reduced the digestive and absorptive capacity of the mucosa, resulting in weight loss and diarrhea of affected pigs.

Repair of microvilli in the rat small intestine after damage with lectins contained in the red kidney bean

That microvilli of intestinal absorptive cells in the duodenum and jejunum are disrupted by acute challenge with lectins contained in raw kidney beans (RKB) was shown nearly 10 yr ago by light microscopy. However, the precise morphologic damage produced by RKB has not been characterized, and it is not known whether microvilli, once damaged, undergo repair. We have examined these issues by challenging rats with suspensions of 300 mg of RKB, boiled beans, or standard laboratory chow by orogastric lavage. Microvillus length was measured in electron micrographs from 6 to 20 h after challenge. Epithelial cell migration was determined by autoradiography after injection of [3H]thymidine. After challenge with RKB, microvilli (a) showed extensive vesiculation along the length of villi 2-4 h after challenge; (b) were reduced significantly in length along the entire villus 6 h after challenge; and (c) were near normal in length by 20 h after challenge. Microvillus length was also reduced significantly 6 h after challenge with boiled beans. The rate of cell migration was not accelerated by treatment with RKB. These data suggest that damage to microvilli caused by 300 mg of RKB is self-limited and reversible; microvilli once damaged by RKB are repaired. Repair of microvilli is due to intrinsic reparative processes rather than accelerated replacement of damaged cells. We speculate that microvilli may be repeatedly damaged and repaired after ingestion of dietary lectins.

The interaction between plant lectins and the small intestinal epithelium: a primary cause of intestinal disturbance

The literature concerning the effects of plant lectins on the small intestinal epithelium is reviewed. It appears that after oral intake, intact plant lectins can reach the small intestinal lumen. Their binding to the mucosal surface evokes an increased synthesis of glycoproteins and a degeneration of the intestinal epithelium. The epithelial alterations may result in hyperregenerative villus atrophy and endogenous nitrogen loss. These changes ultimately can lead to less efficient feed conversion, diminished growth, scouring, wasting and death. The possible significance of plant lectins in digestive disturbances in farm animals is suggested.

Histological alterations to the pancreas and the intestinal tract produced by raw faba bean (Vicia faba L. minor) diets in growing chicks

1. Inclusion of raw faba bean (Vicia faba L., minor) in the diet of growing chickens was shown to affect the performance of the birds and to produce a significant increase in the relative weight of the pancreas. This was attributable to dietary trypsin inhibitors. 2. Trypsin inhibitors also produced degenerative changes in pancreatic acinar cells. These were observed by light and electron microscopy. 3. Progressive cytopathological changes were observed in the intestinal tract. The duodenum, jejunum and ileum were altered, with extensive erosion, shortening and atrophy of microvilli. 4. The results endorsed previous findings obtained using different legume seed lines (Phaseolus spp). Faba bean produced similar local reactions in the pancreas and the intestine. This may be caused by the presence of lectins in the seeds.

Immunogold localization of ingested kidney bean (Phaseolus vulgaris) lectins in epithelial cells of the rat small intestine

The interactions between dietary kidney bean (Phaseolus vulgaris) lectins and the epithelial cells of the rat small intestine were investigated by immunogold electron microscopy. The results demonstrated that the lectins bind to the glycocalyx of duodenal and jejunal microvilli and that some of these dietary constituents are endocytosed into lysosomal pathways within both absorptive and secretory gut cells. It is concluded that the lysosomal response serves to limit the absorption of nutritionally significant levels of these dietary toxins.

Effect of kidney bean (Phaseolus vulgaris) toxin on tissue weight and composition and some metabolic functions of rats

Inclusion of raw kidney bean (Phaseolus vulgaris) proteins in the diet for rats was shown to affect the weight of some internal organs. Of these, in addition to the well-known hypertrophy of the pancreas attributable to dietary trypsin inhibitors, the observed atrophy of the thymus and the doubling in weight of the small intestine are related to the protein or lectin content of the bean diet, or both. Changes in tissue composition of the small intestine were also recorded. Its protein content increased by about 40-50% and carbohydrate content doubled suggesting the occurrence of increased mucinous glycoprotein secretion. Increased DNA content (by about 30-40%) however also indicated mucosal hyperplasia. Changes were also observed in mineral content, urea concentration and some enzyme activities in sera and urine, possibly as a result of disturbances in systemic metabolism or hormone levels, or both. The results gave further support to previous suggestions that the oral toxicity of kidney-bean lectins involves local reactions in the small intestine in combination with their effects on the systemic immune system and general metabolism.