Toxicology Facts

Fava beans

The Fava bean (Vicia faba)

Fava beans (Vicia faba) are grown as a food crop. There are a few potential problems that can occur with fava bean consumption. A more common occurence with fava beans than the latter we will discuss is sensitivity reactions to the bean. Young children shouldn't consume fava beans, considering they have a higher than normal preponderance from developing allergic sensitivity. If allergic sensitivity does occur, there is a risk to health, as severe allergic reactions have occured via inhalation of the mere pollen of the fava bean producing plant.

Although rare, there are a percentage of individuals who have a genetic deficiency of an enzyme called glucose-6-phosphate dehydrogenase. Glucuse-6-phosphate dehydrogenase is manufactured by those without th deficiency, and the enzyme functions in biochemical pathways in our cells, which metabolize glucose to make important substances required for metabolism. For example, glucose-6-phosphate dehydrogenase functions in the biochemical pathway known as the HMP (hexose monophosphate pathway). This pathway is designed to make NADPH. NADPH is used to pruduce steroids in the adrenal cortex (gland above each kidney). NADPH is also needed by erythrocytes (red blood cells) for reduction (chemically changing) glutathione. Glutathione is important because it functions (among other things) as an antioxidant, protecting the erythrocyte from the harmful effects of accumulated hydrogen peroxide. Accumulated hydrogen peroxide damages the cell membrane as well as haemoglobin. Therefore, we can see the importance of glucose-6-phosphate dehydrogenase. But how does the deficiency of this enzyme relate to fava beans?? What probably happens is that an increase in peroxide formation occurs with fava bean consumption, and glutathione is not properly reduced. This damages the erythrocyte, with the observed anaemia, agglutination (clotting) and hemolysis (breaking apart) of these blood cells. When the erythrocyte breaks apart, its haemoglobin and other contents are now free to disperse in the blood stream. However, they are filtered by the kidney. This can cause kidney damage. How common is this enzyme deficiency? More than most people think. There are more than one-tenth of a billion people around with some anamoly or deficiency of the enzyme. Each individual mutation or difference causes different levels of illness. Some people show no noticeable sign or experience no symptoms, where others may develop life-threatening illness. Note that individuals with glucose-6-phosphate dehydrogenase deficiency can also develop similar illness if they were to take antimalarial drugs.

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