Worst Foods High in Lectins

A lectin, also known as the “antinutrient” is a type of protein that binds to certain carbohydrates. Just about every organism in the world, from plants to animals to microbes, contains lectins.

There are many types of lectins, and some are completely safe, while others may pose health risks. The difference depends on the amount of lectins present and what type of carbohydrates bind to them. 

Not every lectin is dangerous in the same way. In fact, many types of lectins pass through your digestive system unchanged. And, while the lectins found in plants are considered edible and are usually harmless, they can sometimes still affect your health.

Further, while lectins aren’t affected by digestive enzymes, they are easily broken down by heat. Boiling sources of lectins for just five to 10 minutes appears to reduce lectins’ abilities to bind entirely.

Why You Should Avoid Lectins

Lectins are sometimes dangerous because of how they bind to carbohydrates like sugar. You should avoid certain types of lectins due to a risk of:

Malnutrition

Certain types of lectins can prevent your body from absorbing other substances that have nutritional value. This can eventually lead to serious problems such as malnutrition.

Poisoning

Some sources of lectins are considered seriously poisonous. Castor beans, for example, contain a potent lectin poison called ricin.

Damage to the Digestive System

Certain types of lectin may bind with the walls of your digestive system which can lead to serious problems. Eating one particular lectin, phytohemagglutinin, can lead to severe abdominal pain, vomiting, and diarrhea.

Potential Risk of Auto-immune Response

Some proponents of lectin-free diets claim that lectins can cause symptoms of auto-immune disorders. However, studies are still being done to confirm or deny this idea. Currently, there is no scientific consensus backing up the idea that lectins are connected to any health conditions outside of acute lectin poisoning.

Foods With Lectins

Lectins can be found in many foods that are part of the average American diet. Many sources of lectins are also good sources of important nutrients. Understanding what foods may be dangerous raw can help you remain healthier, longer.

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These six foods are some of the worst sources of lectins in the American diet when consumed raw.

1. Raw Kidney Beans

Red kidney beans are a great source of plant-based protein and they are a low-glycemic-index food. However, it’s critical that you boil them thoroughly before you eat them. Eating raw or undercooked kidney beans exposes you to an incredibly high level of phytohemagglutinin. Cooking beans thoroughly reduces the activity of this lectin to undetectable levels.

2. Peanuts

Peanuts are another form of legume, and like kidney beans, they contain lectins. Peanut lectins can be detected in the blood after eating peanuts in large amounts. While no studies have been done to determine whether this has health effects, it does show that peanut lectins are absorbed by the body.

3. Whole Grains

Raw wheat and other whole grains are high in lectins. Raw wheat germ, which is often sold as a source of fiber, can contain as much as 300 mcg of wheat lectins per gram. If you’re trying to avoid lectins, do not eat raw whole grains.

4. Raw Soybeans

Soybeans are another legume that’s full of lectins. However, unlike some other legumes, soybeans are often eaten toasted or roasted. This type of dry heat does not appear to be as effective at breaking down lectins as boiling. Be cautious when eating raw or toasted soybeans if you are avoiding lectins.

5. Raw Potatoes

Potatoes are part of the nightshade family and contain high levels of lectins. Raw potatoes, in particular the skin, appear to contain potentially harmful lectins that may affect your health.

More studies need to be done to see whether these lectins are the cause of health problems after eating raw potatoes in humans.

Lectin-Free Alternatives

All of the above foods have associated health benefits as well as lectins. In most cases, cooking these foods with “wet” heat, such as stewing, boiling, cooking in sauce, or mixing into dough and baking, breaks down lectins to negligible levels. Simply avoid eating raw legumes, grains, or potatoes, and eat these foods cooked instead.

WebMD Medical Reference Reviewed by Dan Brennan, MD on October 22, 2020

Sources

SOURCES:

Alternative Therapies in Health and Medicine: “Lectins, agglutinins, and their roles in autoimmune reactivities.

Biochemistry 5th Edition: “Lectins Are Specific Carbohydrate-Binding Proteins.”

British Medical Journal: “Do dietary lectins cause disease?”

Clinical and Experimental Immunology: “Potato lectin activates basophils and mast cells of atopic subjects by its interaction with core chitobiose of cell-bound non-specific immunoglobulin E.”

Food and Drug Administration. Bad Bug Book,  Foodborne Pathogenic Microorganisms and Natural Toxins. Second Edition. “Phytohaemagglutinin. 2012.”

Harvard School of Public Health: “Lectins.”

Lancet: “Identification of intact peanut lectin in peripheral venous blood.”

Methods in Molecular Medicine: “Assessment of Lectin Inactivation by Heat and Digestion.”

Nutrients: “The Dietary Intake of Wheat and other Cereal Grains and Their Role in Inflammation.”

Toxicon: Antinutritional properties of plan lectins.”

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