What are lectins?

Lectins are proteins commonly found in many plant sources. Raw legumes such as lentils, beans, soybeans, peanuts, and peas are rich in these proteins, while whole grains like wheat contain the highest quantities of lectins and they are bad because they can cause digestive issues.
Lectins are proteins commonly found in many plant sources. Raw legumes such as lentils, beans, soybeans, peanuts, and peas are rich in these proteins, while whole grains like wheat contain the highest quantities of lectins and they are bad because they can cause digestive issues.

Lectins are proteins commonly found in many plant sources. Recently, many diet regimens have linked lectins to severe health conditions and have suggested reducing their intake. We’ll look at some of the major lectin sources, potential health risks, and whether there is any truth to these claims about lectins.

Lectins (also known as hemagglutinins) are proteins found in many foods. These proteins have been the topic of much interest recently as research has identified them as potential contributors to health conditions like obesity, autoimmune diseases, and chronic inflammation.

Raw legumes such as lentils, beans, soybeans, peanuts, and peas are rich in these proteins, while whole grains like wheat contain the highest quantities.

Lectins are abundantly found in plants and animals and are known to attach themselves to carbohydrates. Lectins are part of a plant’s defense mechanism, and humans find it harder to digest lectins when they bind to carbohydrates.

In their active state (when foods containing lectins are eaten raw), lectins may lead to digestive issues such as nausea, vomiting, and diarrhea. Some studies have shown that lectins may block the absorption of other nutrients like iron, phosphorus, zinc, and calcium. Lectins are sometimes referred to as “anti-nutrients.” More research is needed to identify the extent of this effect. Interestingly, the foods containing lectins are rich in these nutrients on their own. 

But it’s not all gloom and doom when it comes to lectins. Your daily diet contains only trace amounts of lectins in their active form. Food sources high in lectins, such as legumes and grains, are usually cooked before they’re eaten. This process drastically reduces the harmful effects of lectins. This happens through a process called “denaturing,” which changes the protein structure and lowers its potency.

Lectins may lead to certain health conditions

Although lectins in food sources are usually not a health concern, they may sometimes cause complications. There are some lectins that the digestive enzymes in your body cannot break down enough to pass through your stomach without being altered. 

Although plant sources that contain lectins are not a cause for concern, lectins in some foods such as raw kidney beans may cause complications. Raw kidney beans contain a toxic lectin called phytohaemagglutinin, which may cause kidney bean poisoning. Most cases of kidney bean poisoning have been reported due to improperly cooked kidney beans. Cooking them correctly reduces their harmful effects.

According to the U.S. Food and Drug Administration, eating just four raw kidney beans could lead to serious symptoms such as nausea, diarrhea, and vomiting.

Some research has shown that certain lectins could be fatal even in small amounts. A 2019 study found that ricin in castor beans is very toxic, but most research attributes the harmful effects of lectins to the fact that they can move through the gut without being digested and can cause several local and systemic effects.

People with existing metabolic conditions such as irritable bowel syndrome may be more sensitive to lectins in their digestive system. But completely avoiding foods that contain lectin may also be harmful. Foods that contain lectins are also rich in other nutrients, and limiting such foods could prevent your body from getting proper nutrition.

Risks of a lectin-free diet

A lectin-free diet may be harmful because your body gets many other important nutrients from food sources that contain lectin. A lectin-free diet typically avoids whole grains, beans, legumes, and some vegetables, which have their own health benefits.

A 2016 study found that eating whole grains lowers the risk of death and many other health conditions such as diabetes, heart diseases, and cancer. Many fruits and vegetables also contain lectins and have several other health benefits. They can reduce the risk of metabolic diseases and cancers with the help of bioactive compounds such as polyphenols, isothiocyanates, and terpenoids. Food sources that contain lectin are rich in other nutrients such as B vitamins, minerals, and healthy fats. You don’t want to cut out these healthy options. 

Legumes and whole grains are also rich sources of dietary fiber that aid digestion and keep your gut healthy. Depriving your body of such critical nutritional foods may have harmful long-term effects.

This is especially true for people who follow a vegetarian or a vegan diet, as legumes and whole grains are important sources of plant proteins.

Lectins also have some health benefits themselves. Research has shown that lectins are potent antioxidants that reduce the negative effects of free radicals. They also lower metabolism and the absorption of carbohydrates into your system, preventing any sudden spikes in blood sugar. There are many studies on the benefits of lectin in treating cancer due to its ability to cause cancer cell death.

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How to reduce lectins in your diet

One thing to remember is that very few foods have a high lectin content. Research also suggests that lectins are most effective when eaten raw, but most foods containing lectins are typically cooked or steamed. Lectins are water-soluble molecules usually present in outer layers. Washing foods that have lectins with water or cooking them is enough to remove most of the lectin content.

For example, legumes like chickpeas and dried beans contain lectins on their outer surface. Boiling them or soaking them in water for a few hours is enough to inactivate most lectins.

Lectins consist of a wide variety of proteins, most of which don’t negatively impact your health. Studies have found many food sources rich in lectins to be good for your health.

Denying your body the nutrients from these food sources could be more harmful than eating them, and research on the impact of lectins on your body is still inconclusive. Choosing a lectin-free diet would likely be a drastic change from your regular eating habits, so you should check with your doctor to see if such a diet is good for you.

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Medically Reviewed on 9/16/2022
References
SOURCES:

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

British Medical Journal: "Food poisoning from raw red kidney beans," "Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause specific mortality: systematic review and dose-response meta-analysis of prospective studies."

Department of Health, State Government of Victoria, Australia: "Vegetarian and vegan eating."

Food Research International: "Bioactive food compounds, epigenetics and chronic disease prevention: Focus on early-life interventions with polyphenols."

Harvard T. H. Chan School of Public Health: "Lectins."

Journal of Cereal Science: "Health effects of wheat lectins: A review."

Nutrients: "Dietary Fibre from Whole Grains and Their Benefits on Metabolic Health."

Samaritan Health Services: "Are Lectins in Plant-based Foods Your Friend or Foe?"

The U.S. Food and Drug Administration: "Handbook of Foodborne Pathogenic Microorganisms and Natural Toxins."

World Journal of Gastroenterology: "Dietary Lectin exclusion: The next big food trend?"