Fava beans are a staple food in Mediterranean diets; however, they contain a glycoside compound called vicine, which generates free oxygen radicals and H2O2 when it is metabolized in red blood cells. The enzyme glucose-6-phosphate dehydrogenase (G6PD), which is part of the pentose phosphate pathway and generates NADPH for cells, helps protect cells against oxidative damage caused by compounds such as vicine. Individuals with a genetic defect in the glucose-6-phosphate dehydrogenase gene (G6PD) get sick from eating fava beans because these individuals are unable to produce high levels of NADPH to counteract the toxic effects of vicine in red blood cells. The name given to this diet induced physiologic condition is favism, which in extreme cases can lead to hemolytic anemia (red blood cell death). Deficiency in the glucose-6-phosphate dehydrogenase enzyme represents the most common human genetic variant linked to metabolic disease, with an estimated 400 million people worldwide carrying G6PD mutations.
Everyday BioChem 