A new fad may have you wondering whether your diet is healthy...or even safe. Here’s the real deal.

What are lectins?

“Most people have never even heard of them, but I believe lectins are the #1 Greatest Danger in the American Diet,” says the website of cardiologist (and Lectin-Shield supplement salesman) Steven Gundry, author of The Plant Paradox.

Lectins are proteins that are found in most plants. Beans and whole grains typically have more than other plants.

“Plants don’t exist solely for us to eat them,” explains David Jenkins, a professor of nutrition at the University of Toronto. “Their goal is to survive and reproduce. Lectins are just one of a whole group of compounds that act as a defense system against invaders.”

To protect the plant, says Gundry’s book jacket, lectins “incite a kind of chemical warfare in our bodies,” causing everything from digestive problems, weight gain, and high cholesterol to arthritis, brain fog, and adult acne.

Is there evidence that lectins cause harm?

“I’ve never seen anything in the major medical journals to support that,” says Jenkins. “If there were a problem, we’d know about it. Big time.”

It's true that lectins damage the gut in studies that feed animals raw beans or pure lectin. But we cook, ferment, or sprout our beans and grains, which deactivates most lectins.

How to cook beans safely

The exception: some slow cookers and some casseroles may not reach temperatures high enough to break down all the lectins in raw beans. That can lead to lectin toxicity, especially with red kidney beans. The resulting nausea, vomiting, and diarrhea can last for several hours.

To be safe, soak dry beans in water for at least five hours, pour off the water, and boil briskly in fresh water for at least 10 minutes. Then finish cooking them on the stove or in a slow cooker. Canned beans are already cooked.

Don’t let lectins scare you away

“Some of the healthiest populations around the world eat the most beans and whole grains,” says Jenkins.

The bottom line

Thoroughly cook, don’t avoid, beans and whole grains.