Are there toxins in dried, uncooked beans?

Kathleen Purvis / The Charlotte Observer /


Q: Is it true that uncooked dried beans are poisonous?

I bought garbanzo bean flour to make my own hummus. Is there any danger to eating this flour uncooked?

A: This is a case of a little bit of truth leading to a lot of worry. Dried beans do have lectin, a type of protein, called phytohemagglutinin, or PHA. And while PHA is toxic in large amounts, only red kidney beans are high enough in PHA to be an issue. Most dried beans, including garbanzos (also called chickpeas), have much smaller amounts.

PHA is reduced by boiling beans for 10 minutes — a lot less time than it takes to cook dried, soaked kidney beans. By the time you soak and cook the beans, the PHA problem is gone. There have been a few cases of people suffering stomach distress after cooking dried kidney beans in a slow cooker, which doesn’t reach a high enough temperature to deactivate the PHA. But canned beans or beans cooked on the stove are OK.

Commercially made garbanzo bean flour is processed so that the PHA is not a problem. If you’re worried, hummus also can be made from cooked or canned garbanzos.