Favism: When a healthy food becomes a threat
- Abdallah Yussif
- May 9
- 4 min read
Fava beans, also known as broad beans, are a nutritious and protein-rich legume enjoyed in many meals around the world. However, for some individuals, consuming these beans can lead to a dangerous reaction called favism. This article explores the causes, symptoms, diagnosis, and management of this genetic condition, supported by medical research and expert sources.
What is Favism?
Favism is a genetic disorder that destroys red blood cells (hemolysis) after eating fava beans or inhaling their pollen. It is linked to a deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), which helps protect red blood cells from oxidative damage (Luzzatto & Arese, 2018). Without enough G6PD, certain compounds (such as vicine and convicine in fava beans) trigger severe oxidative stress, leading to red blood cell breakdown (Nkhoma et al., 2009).
What is the Function of the G6PD Enzyme?
G6PD plays a critical role in the pentose phosphate pathway, maintaining cellular redox balance by producing NADPH. This reducing equivalent is essential for:
Regenerating reduced glutathione (GSH)
Protecting red blood cells from oxidative damage
Supporting other antioxidant systems
In G6PD deficiency, red blood cells become vulnerable to oxidative stress because they cannot maintain adequate levels of NADPH and reduced glutathione (Nkhoma et al., 2009).
Genetic Inheritance
The G6PD gene is located on the X chromosome (Xq28), resulting in:
Males: Hemizygous (single X chromosome) - one defective allele causes deficiency
Females: Homozygous (two defective alleles) needed for full deficiency
Female carriers may show partial deficiency due to X-chromosome inactivation
Over 200 G6PD variants have been identified and classified by enzyme activity level:
Class I: Severe deficiency with chronic hemolysis
Class II: Severe deficiency (<10% activity)
Class III: Moderate deficiency (10-60% activity)
Class IV: Normal activity
Class V: Increased activity
The Mediterranean (G6PD Med) and African A- (G6PD A-) variants are most commonly associated with favism (Frank, 2005)
Who is at Risk?
Favism is most common in people of Mediterranean, Middle Eastern, African, and Southeast Asian descent, where G6PD deficiency is more prevalent (Cappellini & Fiorelli, 2008). The likelihood of Males being affected is greater than that of females, as the G6PD gene is located on the X chromosome. Since males have only one X chromosome, inheriting a defective gene guarantees they'll have the deficiency. Females, with two X chromosomes, are usually carriers but can develop symptoms if both copies of the gene are affected (Frank, 2005).
Symptoms of Favism:
Symptoms typically appear within 24 to 48 hours after consuming fava beans or exposure to their pollen, these symptoms can range from mild to life-threatening. Common signs include:
Fatigue and weakness (due to anemia)
Pale or yellowish skin (jaundice)
Dark-colored urine (from hemoglobin breakdown)
Rapid heart rate and shortness of breath (as the body struggles to deliver oxygen)
Back or abdominal pain (from kidney stress)
Fever and chills
In severe cases, favism can lead to acute hemolytic anemia, kidney failure, or even death if not treated promptly (Mason et al., 2007).
Diagnosis and Management:
If favism is suspected, a blood test can confirm G6PD deficiency (World Health Organization [WHO], 2021). The best way to prevent a reaction is strict avoidance of fava beans and related triggers. Key management strategies include:
Dietary precautions: Avoiding fava beans and checking food labels for hidden ingredients.
Medication awareness: Some drugs (like certain antimalarials, sulfa antibiotics, and pain relievers) can also trigger hemolysis in G6PD-deficient individuals (Youngster et al., 2010). Always inform doctors about the condition before taking new medications.
Environmental caution: Staying away from fava bean fields, especially during pollen season.
Treatment during a Favism Episode:
Treatment for an acute favism episode focuses on supportive care to manage the symptoms and complications. In severe cases where significant red blood cell destruction has occurred, blood transfusions may be necessary to replenish the depleted red blood cell count and restore oxygen-carrying capacity. Intravenous fluids are also commonly administered to combat dehydration, a frequent side effect of hemolysis, and to support optimal kidney function, which can be compromised by the breakdown products of red blood cells. Also, oxygen therapy may be required to alleviate breathing difficulties if the reduced red blood cell count impairs oxygen delivery to the tissues.
Living with Favism:
While favism can be a serious condition, early diagnosis can help most individuals with G6PD deficiency live a normal life by carefully avoiding fava beans and other triggers. With careful management and awareness, the risks associated with favism can be significantly minimized. It’s important to consult with a healthcare professional for personalized guidance and management strategies if you suspect you or a loved one has G6PD deficiency.
References
Cappellini, M. D., & Fiorelli, G. (2008). Glucose-6-phosphate dehydrogenase deficiency. The Lancet, 371(9606), 64-74.
Frank, J. E. (2005). Diagnosis and management of G6PD deficiency. American Family Physician, 72(7), 1277-1282.
Luzzatto, L., & Arese, P. (2018). Favism and glucose-6-phosphate dehydrogenase deficiency. New England Journal of Medicine, 378(1), 60-71.
Nkhoma, E. T., Poole, C., Vannappagari, V., et al. (2009). The global prevalence of glucose-6-phosphate dehydrogenase deficiency: A systematic review and meta-analysis. Blood Cells, Molecules, and Diseases, 42(3), 267-278.
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