Do You Really Need to Worry About Lectins? Separating Myth from Fact

Lectins are proteins that are found in most forms of life, including plants, animals, and other organisms. They have several important biochemical functions. And some nutritious foods have a large amount of them. But some diets and authors warn against eating foods that contain lectins. We’ll talk about what lectins are and whether or not they’re harmful. 

What are lectins?

Lectins are a specific type of protein that bind to carbohydrates. Sometimes when people talk about carbohydrates, they mean dietary carbohydrates, like bread products or sweet foods. But in this context, carbohydrates mean individual sugar molecules, like:

• Glucose

• Galactose

• Mannose

• Xylose

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Each lectin binds to a specific sugar molecule. The way lectins bind to sugar molecules is important for the way they function. And lectins have many functions, including:

• Cell communication 

• Tissue development

• Immune response

Lectins are important for normal biochemical functioning. So it’s no surprise that they are found in many forms of life. Lectins are in viruses, bacteria, fungi, and plants. They’re also found in animals, including humans. But lectins are most abundant in plants — especially in certain plants that humans eat for food. 

What foods are high in lectins?

Legumes — plants in the bean family — contain the highest amount of lectins. Examples include:

• Common beans (kidney, pinto, black, and white beans)

• Soybeans

• Chickpeas (garbanzo beans)

• Fava beans

• Peas

• Lentils

• Peanuts

Some other plant-based foods also contain high levels of lectins. For example, whole grains, like wheat, have a large amount of lectin. Lectins in beans and wheat have been studied the most because they’re common food sources for humans 

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Lectins are also found in very small amounts in many fruits and non-legume vegetables. More than 500 different lectins have been isolated from plants. Some other foods that contain lectins include:

• Tomatoes

• Potatoes

• Corn

• Avocado

• Almonds 

• Cashews

• Cherries

• Blackberries

• Beets 

• Cabbage

Are lectins bad for you?

Most lectins are harmless for humans. But there are a few situations in which lectins are poisonous:

• Kidney beans: Eating undercooked, raw, or fresh kidney beans can be harmful. About 1 to 3 hours after eating them, lectin toxicity can cause digestive problems like nausea, vomiting, and diarrhea.

• Ricin: This lectin is found in the castor bean plant, which is sometimes used as a decorative planting. It’s poisonous to pets and humans (though humans don’t typically consume these plants). 

• Wheat lectin: Laboratory studies show that wheat lectin has the potential for negative effects if taken raw or in abnormally high concentrations. It has not been shown to cause any adverse health effects when consumed in baked or cooked foods.

Why are lectins controversial?

Some refer to lectins as antinutrients. This is a term for substances that make other nutrients less available, or are otherwise harmful to humans. But the term “antinutrient” itself is controversial. Most research supports the health benefits of foods with lectins.

Some authors and proponents of diet plans have increased awareness of lectins in recent years. They state that lectins cause chronic inflammation, nutritional deficiencies, and obesity. In particular, they’ve suggested that lectins cause these issues because of digestive problems — including the controversial condition called “leaky gut syndrome.”

Research with laboratory animals shows that lectins bind to the sugars on cells lining the gut. In those models, they can interfere with digestion, nutrient absorption, and cell lifespan in laboratory animals. But this research did not study effects in humans.

There are a few problems with linking dietary lectins to chronic diseases:

• It’s unclear if these problems can be caused by lectins alone. Chronic health issues are influenced by many factors.

• There’s a lack of human studies. Most studies of lectins are done using animal subjects or lab-grown cells. Experts say that more research is needed to know if lectins affect gut health in humans. 

• The research in question involved isolated lectins — not whole foods. Plant foods contain many other compounds that may decrease possible harm caused by lectins.

Do you need to avoid high-lectin foods?

To avoid all lectins, you would have to stop eating fruits, vegetables, nuts, and grains. That would not be nutritious or even feasible for most people. Small amounts of lectins in these foods are fine to consume. 

Plus, foods that are high in lectins are among those that are very good for overall health. If you avoid legumes and whole grains because they contain lectins, you’ll miss out on a good source of fiber, protein, and phytonutrients. Strong research supports the health benefits of eating a plant-based diet. 

The good news is that it’s easy to remove lectins from high-lectin foods, if you wish. Almost all lectins can be removed from foods by usual cooking methods. Ways to remove lectins include:

• Soaking

• Boiling

• Pressure-cooking

• Fermenting

Why trust our experts?

Written by:

Katherine Krive, DO

Katherine Krive, DO, is a freelance medical writer and editor. She is also a psychiatrist who has practiced in hospital, academic, and community settings.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

Reviewed by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined her interests in clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

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