Pythagoras, fava beans, and favism

By Roberta Attanasio

Pythagoras—a cloak-wearing mystical leader with a handsome beard—lived about 2,500 year ago in a community that cherished numbers. He was a native of the Aegean Island of Samos, but later in his life migrated westward and founded a school in Kroton (now Crotone) in South Italy. The school was called the “Semicircle of Pythagoras” and followed a code of secrecy. It was a cradle of mathematical research, but it had also an ascetic and religious character. Notably, Pythagoras’ philosophical views influenced both Plato and Aristotle.

Although his famous theorem about right-angled triangles was likely developed by the Babylonians, Pythagoras is considered the first mathematician and a philosophical giant. He dreamed the dream that became modern physics and declared “Everything is numbers,” while teaching that the laws of the universe can be described using the language of mathematics and giving divine meaning to each number. “The Pythagorean Theorem is arguably the most famous statement in mathematics, and the fourth most beautiful equation.” Unrelated to any theorem or mathematical equation, there is also a famous Pythagorean rule known as “Be far from the fava bean consumption.” Indeed, Pythagoras was likely the first to state that fava beans (Vicia faba) can be dangerous or even lethal to humans.

Fava beans, also known as “broad beans,” are one of the oldest domesticated crops. They are native to North Africa and Southwest Asia, and extensively grown in temperate climates throughout the world. China, Ethiopia, Egypt and France lead worldwide production. Characterized by large green and leathery pods, fava beans are a fleeting spring vegetable, with a rich, nutty, green flavor. They can be found only from late March through May, but are a staple in many culinary traditions, especially for Mediterranean populations.

In the Middle Ages, when Sicily experienced a severe drought that led to hunger and crop destruction, fava beans acquired magical status. According to legend, Sicilians prayed to Saint Joseph for rain, promising him to celebrate his day with the “Saint Joseph’s table”, an altar with special foods as their thanksgiving for his great miracle. San Joseph made it rain, and the fava beans were the only crops that survived the drought, helping prevent a famine. Since then, Sicilians have honored Saint Joseph annually on March 19th. Part of the festivities on Saint Joseph’s Day include eating dishes made with fava beans.

So why did fava beans get such a bad rap in ancient times? We now know that, in susceptible people, fava beans cause “favism”—a hereditary disease and the most common form of acute hemolytic anemia. It presents as a severe allergic-like reaction with paleness, yellowing of the skin and whites of the eyes (jaundice), dark urine, fatigue, shortness of breath, and a rapid heart rate. Favism occurs when people with a hereditary deficiency of the enzyme glucose-6-phosphate dehydrogenase eat fava beans. The disorder causes red blood cells—which carry oxygen from the lungs to the tissues of the body—to be destroyed faster than they can be made. If left untreated, it can be fatal.

However, in ancient times, the Orphics believed that Pythagoras had forbidden the consumption of fava beans because they contained the souls of the dead. “Eating fava beans and gnawing on the heads of one’s parent are one and the same” was one of their saying. They referred to their obsessive fear of fava beans as “horror fabae.” Pythagoras refused to walk through fields of fava beans and discouraged his disciples from eating them. It is said that he died in Crotone at the edge of a fava bean field because, pursued by his enemies, refused to flee across it. “Ancient philosophers including Aristotle and Cicero attempted to explain Pythagoras’s aversion to fava beans. One theory was they were forbidden due to their resemblance of both male and female genitalia. It was also believed a chewed bean smelled like the blood of a murder victim when left in the sun. Some thought their unsegmented hollow stem functioned as the gates of Hades. Similar to an elevator, it was theorized the stem transported souls between worlds.” 

Researchers speculate that Pythagoras may have suffered from favism. However, it is also likely that his aversion to fava beans was motivated by the mystical and magic properties his community ascribed to them. We may never know why Pythagoras came out with “Be far from the fava bean consumption”, but we not for sure that people with glucose-6-phosphate dehydrogenase deficiency should not eat fava beans.  

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