Lectins in Beans and Whole Grains Making us Sick?

A new fad has surfaced based on a cardiologist who wrote on his website “I believe lectins are the #1 Biggest Danger in the American Diet”. “They 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. This has raised many questions and concerns, but let’s review the facts.

Lectins are proteins that are found in most plants. Whole grains and beans grains usually have higher amounts of lectins than other plants. Animal studies have shown that lectins damage the gut when animals are fed raw beans or pure lectin. However, humans either cook, ferment, or sprout the beans and grains, which deactivates most lectins.

Some slow cookers or casseroles may not reach temperatures high enough to break down all the lectins in raw beans. That can lead to lectin toxicity, particularly with red kidney beans. The side effects are usually nausea, vomiting, and diarrhea which can last for several hours. To be safe, soak dry beans in water overnight or for at least 5 hours, pour off the water, rinse and boil briskly in fresh water for at least 10 minutes. Then finish cooking them on the stove or in a slow cooker.

Don’t let lectins scare you away, beans and lentils are a great source of fiber, folic acid, iron and potassium. Some of the healthiest populations around the world eat the most beans and whole grains. Researchers at the University of Cambridge who assessed the consumption of healthy foods including fruit, vegetables, whole grains, fish, and food high in fiber and omega 3 found that diets in West Africa ranked the highest. In general, they consumed less processed foods with an increase of pulses, beans and staple cereals.


Gastroenterology 82: 838, 1982.

  1. Agric. Food Chem. 39: 1627, 1991.
  2. Agric. Food Chem. 50: 6592, 2002.

Lancet Glob Health. 2015; 3: e132–42


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