Phytohemagglutinins. Their nutritional significance

Abstract

Substances which have the ability to agglutinate red blood cells, the so-called phytohemagglutinins or lectins, are widely distributed in the plant kingdom. The fact that the lectins are found in those legumes which constitute an important source

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“…Foods with high lectin content (legume seeds, cereal grains, nuts etc. ), if consumed in excess, in uncooked or partially cooked form, can cause gastrointestinal distress [39,51,62] . There is mounting evidence implicating lectins as the trigger factor for peptic ulceration [61] .…”

“…Decreased susceptibility of secretors to ulceration can be attributed to the presence of water soluble blood group substances (glycoproteins) in large amount in brush border cells lining the gut, which act as a defense against the mucus stripping effect of lectins in food, and protect the epithelium from heavy colonization of Helicobacter pylori. Some other factors influencing the onset and development of peptic ulcer disease are, a lectin rich diet [24,39,51,62] , ABO phenotype [11,12] and preferential affinity of H.…”

“…It has been shown that among the large group of so called nonspecific lectins, there are many which react selectively with human and animal red cells [34] , indicating that the nonspecific lectins too have a measure of specificity. The interaction of nonspecific lectins with cells can, in many cases, be inhibited specifically by human saliva [8,35,36] and simple sugars [33,37,38,39] . It is clear from the results of hemagglutination and inhibition studies that the nonspecific lectins differ markedly in their reactivity and sugar binding specificity.…”

“…Humans consume a significant amount of lectins as part of their daily diet. Although many of the dietary lectins are inactivated by proper heat treatment, some lectins found in wheat bran, wheat flour, wheat germ, peanuts, dry cereals, carrot, maize, apple, pumpkin, banana etc., survive cooking [7,39,42] . Grant and coworkers [43] demonstrated that the kidney beens that have been heated for several hours in slow cookers are likely to retain enough lectins to cause gastroenteritis, especially, if not pre soaked before cooking.…”

“…The toxicity of lectins has been linked with consumption of food with high lectin content. Foods such as beans, cereal grains, potatoes, nuts etc., which contain lectins in high concentration, if consumed in excess can interact with mucosa to cause acute gastrointestinal symptoms in experimental animals [39,51,62] . One of the effects observed in the small intestine of lectin-fed rodents is stripping away of mucous coat to expose naked mucosa, and overgrowth of the mucosa by abnormal bacteria and Protozoa [63] .…”