As mentioned earlier, glucose-6-phosphate dehydrogenase deficiency can lead to haemolytic crisis by interaction with infections, drugs and food. Ingestion of fava beans (Vicia faba) in the fresh, frozen and dried forms have long been held to be able to cause haemolysis, the phenomenon being known as favism. It's occurrence is common in countries of the Middle East and the Mediterranean especially during spring. 3. 21.Haemolysis in breast-fed babies whose mothers have ingested fava beans have also been reported. 1. 4.Although all persons with favism are glucose-6-phosphate dehydrogenase deficient, not every glucose-6-phosphate dehydrogenase deficient subject develops haemolysis after ingestion of fava beans. 3.Favism appears to affect only the Mediterranean type while the African type generally remains unaffected. 1.
Fava beans are rich in two glycosidic compounds, vicine and convicine which account for nearly 2% of the dry weight. Upon ingestion, the glycosides are hydrolysed enzymatically to form pyrimidine aglycones, divicine and isouramil respectively (Figure 4).The proposed mechanism for the cause of favism is that these new compounds then undergo redox cycling and in the process depleting reduced glutathione (GSH), leading to the formation of free radicals and hydrogen peroxide. 1. 9. 17.
The unpredictable nature of favism has often been a source of debate. The opposing school of thought holds that "favism" is not related to the ingestion of fava beans. This standing was illustrated in a study done on 102 patients with no previous history of drug induced haemolysis who have been consuming fava beans on a regular basis without developing any ill effects up to the point of the haemolytic episode. Three patients from this group who have recovered from the haemolytic episodes were then challenged 2-3 months later with fava bean consumption for at least one month each. None of the three developed any haemolytic episode when challenged. The authors suggested that other factors must be involved in the haemolytic episodes e.g. viral infection. 21.
Fava beans is a staple food for many Mediterranean countries. Due to the fear of favism, many parents of glucose-6-phosphate dehydrogenase deficient children have resorted to restricting the diet of fava beans. In doing so, they unknowingly deprived the children of many common food items which do not cause favism, for example peanuts, lentils, green peas, chick peas and nuts. The source of confusion is believed to arise from the naming of these food e.g. fava beans called foul in Arabic, peanuts called foul-Sudani and soy beans called foul-al-Soya. 17.
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Prepared on 01 Jan 2008 by teekoonhien |
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