The first Natural toxicant in legumes are Hemmagglutins and lectins
These are naturally occurring constituents that are mainly in seeds but may also be found in other plants.
They are present at high levels in all legumes and grain products. Fifty _three plants have lectin activity.
Castor beans contain so much of one of the most toxic lectins (ricin) that these beans are unsuitable for use as food.
Lectins can destroy the epithelia of the gastrointestinal tract; interfere with cell mitosis; cause local hemorrhages; damage kidney, liver, and heart; and agglutinate red blood cells, the last of these being the effect after which they are named. A diet of raw black beans can kill rats in four to five days.
Since the toxicity of these compounds is dramatically reduced by cooking with most heat, their use in human diets is little cause for concern except at high altitudes, where the boiling point is reduced, or in situations where heat transfer is terribly uneven.
Toxicity is also reduced because many toxic compounds are destroyed or neutralized in a normal digestive tract and most are poorly absorbed.
Poor absorption means that lectins reach the colon in a biologically intact from and thus can have a beneficial effect.
They appear to protect the human body against colon cancer, either by causing hyper-secretion of intestinal mucus or by exerting a direct toxic effect on tumor cells.
another natural toxicant in legumes which have a soap-like quality from which they get their name.
They are found in soybeans, as well as in alfalfa, spinach, asparagas, broccoli, potatoes, apples, eggplant, and ginseng root.
Saponins are capable of disrupting red blood cells and producing diarrhea and vomiting.
On the plus side, they may have the pharmacological function of complexing with cholesterol and reducing serum cholesterol.
Small concentrations are generally harmless to warmblooded animals because intestinal micro-flora destroy them and blood plasma inhibits their action. Ginseng ( a common component of herb teas), with its high saponin content, has been shown to cause nervousness, mood alternations, anorexia, hypertension, edema, sleeplessness, amenorrhea, and diarrhea.
Whether these effects are due to sapoonins to other factors in the ginseng in unknown.
3) VICINE AND COVICINE IN FAVA BEANS.
These are other natural toxicants in legumes, fava or broad beans are widely eaten in England and countries around the Mediterranean and are associated with the disease favism.
Favism falls into the first scenario category; that is, it results from a normal food eaten in normal amounts by an individual with a genetic sensitivity.
t s an inherited, sex-linked metabolic disturbance occurring in some people of Mediterranean and Asiatic origin.
It is also seen in parts of Africa and among African-Americans. Eating of fava beans by genetically sensitive individuals results in a hemolytic anemia and hemauturia (blood in the urine) caused by the rupturing of the older red blood cells by the fava bean nucleosides, vicine and covicine. Children are especially susceptible and favism is occasionally fatal.
4) Other natural toxicants in legumes,(fava beans)Due to their high levels of monoamine oxidase inhibitors, which can cause headaches, palpitations, and sharp increases in blood pressure, fava beans can also been implicated as having a carcinogenic compound possibly related to a high incidence of certain types of cancer in Latin America.
5) Lathyrogens, another disease caused by natural toxicants in legumes, (SWEET PEA)Lathyrism is a neurological disease that occurs in India, China, parts of Africa, and the areas around the Mediterranean, especially Spain.
Its incidence increases during periods of drought when people are forced to eat sweet pea (Lathyrus Sativus) and vetch, which contain lathyrogens, unusual amino acids.
In lathyrism, altered metabolism of the connective tissue results in skeletal and aortic abnormalities. Symptoms occur after several months on a diet of these foods.
The nervous system is also affected because the metabolism of the neurotransmitter glutamic acid is impaired. This results in weakness, irritability, tremors, spasticity, jerky motions, and even convulsions.
Neurological effects are seen only in humans, and males are much more susceptible than females.
6) Other toxicant factors in beansAn as-yet-unidentified factor of common beans has been reported to cause pulmonary damage when fed to rats.
The damage decreased lung capacity and caused lung tissue damage as seen under a microscope.
7) Goitrogens as natural toxicants in legumesSoybeans, pine, nuts, peanuts, and millet, as well as fruits and vegetables, contain goitrogens, substances that cause goiters .
The genus Brassica, which is the primary dietary source of goitrogens (glucosinolates), includes broccoli, Brussels sprouts, cabbage, cauliflower, horseradish, kale, kohlrabi, mustard, and mustard seed.
Tow members of this family, turnips and rutabaga, are particularly high in goitrogens.
Carrot, peach, pear, radish, and strawberry may also contain goitrogens.
Milk also may be a source, if one of the Brassica species such as turnips was used as fodder.
Cooking and freezing reduce the amount in milk or vegetables.
A high intake of these vegetables with an inadequate intake of iodine could precipitate goiter.
The use of soy milk by infants also could be a potential problem if iodine is not part of the diet or formulation.
Goitrogenic foods are thought to be responsible for 4% of the world’s goiter cases. In Zaire and Sudan, the use of the staples cassava and millet, together with lack of adequate iodine, results in over half the population having goiter.
Protein-poor diets appear to increase the antithyroid effects of goitrogens . The risk of large amounts of cooked vegetables containing these compounds in otherwise adequate diets is unknown.