Known since ancient times as “bean disease”, this pathology, as can be seen from the word itself, involves the absolute need to avoid the intake of broad beans and other foods, such as peas and verbena, some medicines and particular substances.
In subjects affected by favism, said fabiana d. is recordedefficiency of an enzyme implicated in the biogenetic pathway of pentose phosphates, glucose-6-phosphate dehydrogenase (G6PD).
The deficiency of the enzyme leads to serious consequences at the level of erythrocytes (red blood cells), since G6DP is essential for their correct functioning and survival.
The intake of particular foods and substances could inhibit the G6DP enzyme, resulting in very serious consequences for the organism, including acute hemolysis with jaundice or hemolytic crisis.
The term “favism”, however, is inappropriate, since in some fab subjects the clinical hemolytic reaction can occur independently of the consumption of broad beans and peas.
However, in most cases, affected people cannot eat these legumes; furthermore, other substances, such as naphthalene and certain drugs, which can aggravate the pre-existing condition, cannot be taken or inhaled.
The deficiency of the enzyme glucose-6-phosphate dehydrogenase, as we have seen, is the trigger that causes acute hemolysis with jaundice. In fact, the role played by this enzyme as a defense factor of erythrocytes against oxidation is known.
The drugs and substances mentioned above alter the oxidative balance, behaving as pro-oxidants.
But what are the drugs to avoid?
Some analgesics, antipyretics, antimalarials, salicylates, certain chemotherapy drugs, quinidine, methylene blue, etc.
Symptoms and complications of favism
The subject suffering from favism, 12-48 hours after ingesting peas, broad beans or particular drugs, manifests a fabic syndrome, characterized by a yellowish complexion that sometimes tends to green, the sclerae of the eyes appear intense yellow, the urine is dark.
If favism occurs in a severe form, the subject could have cardiovascular collapse: jaundice is caused by a high concentration of bilirubin in the blood, a catabolic (waste) product of hemoglobin contained in red blood cells.
If jaundice progresses, the disease may progress to the more severe form of kernicterus (bilirubin encephalopathy: bilirubin is deposited in the brain, resulting in brain damage and possible mental retardation).
Furthermore, hemolytic anemia could occur not only following the intake of substances prohibited in this disease, but also as a consequence of pneumonia, viral hepatitis, malaria and diabetic ketoacidosis.
There are various forms of favism and, based on the severity, the WHO (World Health Organization) distinguishes five levels:
- the first two express a serious deficiency (chronic hemolytic anemia / acute renal failure and intermittent hemolysis),
- the third represents a mild deficiency (hemolysis manifested only in case of contact with oxidizing substances – broad beans, peas, analgesic drugs, naphthalene etc.),
- while the last two do not cause any dangerous clinical effects.
The broad bean disease is transmitted hereditarily with the X chromosome (as a recessive trait connected to the sex chromosome X): for this reason males are more affected than females, who are generally healthy carriers.
The deficiency of the G6DP enzyme represents one of the most frequent enzyme deficiencies in the world, considering that it affects approximately 400 million subjects. It should be remembered, however, that in the majority of cases, favism remains asymptomatic (it has no consequences for the organism).
The only cure is prevention: affected individuals must scrupulously abstain from taking broad beans and peas, as they contain pro-oxidant substances in the seeds (vicina and convicina); analgesic, antipyretic, antimalarial drugs, methylene blue, naphthalene, sulphonamides, NSAIDs and some antibiotics must be banned.
Blood transfusions, in the case of an acute hemolytic crisis, and dialysis for patients suffering from kidney failure, are vital.
In some serious cases, removal of the spleen may be the only solution: in fact, it is precisely at the spleen level that the red blood cells are destroyed.
Careful and scrupulous diagnosis of the disease is essential before adopting any treatment: the diagnostic test searches for the enzyme glucose-6-phosphate dehydrogenase within the erythrocytes, highlighting even the slightest deficiencies.
Unfortunately, the possible variants of the broad bean disease there are so many, and so little in-depth research, that there is still an evident concern about possible foods, drugs and substances that are truly dangerous for affected subjects: in some cases, it almost seems that only broad beans are really implicated.
According to some ancient legends, favism was also connected to spiritual factors: in fact, it seems that beans were somehow connected to the World of the Dead and were considered a symbol of impurity and decomposition.