Fact. Fava beans contain compounds that can destroy the red blood cells of an individual lacking a specific enzyme. In some Mediterranean, African or Pacific Rim regions, the genetic defect that causes the reaction is carried by as much as 20 percent of the populations. But in the United States, it’s rare.

According to Dr. Steve Kornfeld, a hematologist with Bend Memorial Clinic, a small percentage of people – far less than 1 percent of the population – lack the enzyme glucose-6-phosphate dehydrogenase, or G6PD. The enzyme deficiency can lead to oxidative stress – a build-up of oxygen chemicals – that causes the sudden destruction of red blood cells if the person eats fava beans or takes certain medications.

”It’s like suddenly you’ve lost most of your blood,” Kornfeld says. ”You’re very, very sick.”

While people have died from ingesting fava beans without knowing they had the deficiency, a blood transfusion is generally sufficient to treat even the worst reactions. The deficiency has more than 400 different variants with varying degrees of severity.

”In some people, it’s so mild, the oxidative stress has to be huge,” Kornfeld says. ”In other people, the enzyme is so susceptible, it doesn’t take much.”

Kornfeld says that whenever he sees a patient whose red blood cells have been destroyed, G6PD deficiency immediately comes to mind.

But most often, it’s because of a reaction to a medication rather than fava beans.

Tests can determine whether someone has the deficiency, but given the numbers involved, routine screening isn’t practical.

”Are you going to screen everybody who’s born to find a few of those people and say don’t eat fava beans?” Kornfeld says.

Symptoms of the anemic reaction in deficient individuals include an abnormal paleness or yellowing of the skin, dark colored urine, fever, weakness, dizziness, confusion and increased heart rate. Those identified with G6PD deficiency are generally given a list of medications and foods to avoid, including fava beans.

– Markian Hawryluk