In the case of favas, the reaction is linked to a genetic hormone deficiency called G6PD, short for Glucose 6 Phosphate Dehydrogenase deficiency.
"An important fact about fava beans is that individuals with G6PD hormone deficiency, also known as 'Favism,' often - though not always - have a very serious allergy to fava beans," said Tom Roberson of Sacramento. "Our 5-year-old son has the G6PD deficiency, so we carefully avoid fava beans.
"The G6PD deficiency is very common around the world, and, I believe, is now routinely tested for at birth," he added.
According to medical experts, G6PD deficiency is seen in about 10 percent of African-American males in the U.S., and is also common in the Mediterranean region, Africa and parts of Asia.
Learn more about G6PD at http://g6pddeficiency.org/wp/.
Most people can eat favas without worry. Favas are entering their peak spring season. For recipes and tips, see http://bit.ly/152qAg9.