G6PD deficiency and favism

On a recent trip to Italy, I came across this notice at the entrance to a popular supermarket.

Translated, it read: “Warning to customers at risk of acute haemolysis caused by favism: fresh broad beans are displayed and on sale in this store“.

Favism is not a food allergy, neither is it an autoimmune condition, and it can only be considered a food intolerance in that those affected by favism cannot ‘tolerate’ broad beans.

The cause is a deficiency of an enzyme called glucose-6-phosphate dehydrogenase (G6PD), one of whose roles is to protect red blood cells. G6PD deficiency is an inherited metabolic disorder, mostly affecting boys and men.

Under normal circumstances, those with G6PD deficiency experience no symptoms or health issues, but with certain environmental triggers — some infectious diseases (e.g. hepatitis), some drugs (quinine, aspirin), mothballs (naphthalene) — red blood cells can become more vulnerable to damage, resulting in anaemia.

Broad beans, or fava beans, are another trigger. They contain two glucosides — called divicine and convicine — which, in the absence of sufficient protective G6PD, damage red blood cells. The resulting symptoms can be severe — jaundice, fatigue, vomiting, brown urine, tachycardia, fever and more — varying considerably in intensity between patients, and dependent on the quantity of fava beans consumed.

Many with G6PD deficiency are undiagnosed, as symptoms can often be mild, and triggers are commonly routinely avoided. Diagnosis can come in much later life, as exemplified by this case report of a male in advanced middle age, following his consumption of a large quantity of broad beans. It is not routinely tested for, but a test may be ordered by a doctor if you are experiencing typical symptoms. 


So why the supermarket sign?

Although I initially stumbled across favism while researching my first book, Living with Food Intolerance, some twenty years ago, I hadn’t realised it could pose such a risk to those those with acute G6PD deficiency.

In fact, it appears even pollen from the fava plant can act as a trigger, and given the open exposure of the beans in the supermarket, Conad clearly felt the responsibility to warn customers. 

Another motivation behind the sign might have been that G6PD deficiency is far more common in Mediterranean, Middle Eastern, African and Asian countries. There are very high rates among Kurdish Jewish populations, as well as in African Americans and Sardinians. 

I’ve always been aware that Italy is highly attuned to all manner of food reactions and dietary needs — a sensitivity commonly manifesting itself culturally in excellent coeliac and gluten-free awareness — but nevertheless I have to confess the sign was a real surprise even to me!

I’ve since found out that local councils sometimes prohibit the cultivation of broad beans close to populated and communal areas. 

Further evidence for this knowledgeable vigilance can be found on the label of the Sicilian chocolate brand, Ciomod — whose products carry a ‘may contain’ warning for fava beans, despite not being one of the top 14 declarable food allergens in the EU. 


Other triggers

Although broad beans are the main dietary trigger, some advocates and doctors advise some patients avoid all beans and other legumes, typically peas, especially in large amounts. The Indian pea, or grass pea, also contains divicine, one of the culprit alkaloids in fava beans. 

Some Chinese and Ayurvedic herbal medicines, high-dose vitamin C supplements, and tonic water with quinine, should be avoided.

There is a highly comprehensive list of foods and additives provided on the G6PD Help Website, although such strict and rigorous avoidance may not be necessary in the majority of cases, and may be dependent on the genetic variant involved in an individual’s condition. 

Curiously, both PPD (a compound used extensively in permanent hair dyes) and henna (a natural compound and alternative base ingredient to PPD-based dyes) are thought to be potential risks, making finding a safe hair dye difficult for those with G6PD deficiency. Although it does contain a velvet bean extract, Hairprint may be the best option. See my article on PPD Free Hair Dye for more information about it. 

Avoidance of exposure to products high in salicylates, aspirin-like chemicals found in many foods, is also sometimes advised. Blueberries are a typical example, but also mint and menthol products, making oral care products a challenge. Some may find a previous article on salicylate-free toothpaste useful, although check for other potentially problematic ingredients too. 

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