Are Lectins Good or Bad for You? Foods to Eat and Foods to Avoid

Lectins are proteins that bind to carbohydrates. Lectins are considered anti-nutrients because they can block the absorption of certain minerals and they are found in legumes and whole grains.

Lectins occur in all plants but are highest in grains and legumes. Popular media paints lectins as harmful to health, but research shows they can be beneficial. If you strive for good health, you may wonder, are lectins good or bad for you? Also, which lectin-containing foods should you eat, and which should you avoid?

Lectins are proteins that bind to carbohydrates. They help plants resist attacks from fungi, diseases, and insects. The qualities that make them valuable to plants can cause problems when humans eat them. All plants contain some lectins, but the sources of most concern are legumes and whole grains. 

Lectins in Legumes

Legumes are a class of plants that includes peas, beans, lentils, and peanuts. They are vital crops worldwide because they use nitrogen from the air and need little fertilizer. They produce relatively low levels of greenhouse gases, and some varieties are drought-resistant. Dried legumes are valuable staples, as they can be dried and stored for long periods. Legumes are a good source of protein, carbohydrates, vitamins, and fiber.  

Lectins in Whole Grains

Lectins also occur in grains, especially whole grains. Some methods used for processing grains strip away everything but the endosperm. Whole grains retain the three parts of the kernel: the bran, the germ, and the endosperm. Each part contains essential nutrients. A diet high in whole grains can help prevent heart disease, type 2 diabetes, cancer, and digestive diseases. 

Most fruits and vegetables contain small amounts of lectins. Eggplant, potatoes, and tomatoes contain somewhat elevated amounts.

Lectins thrive in an acidic environment, so they resist digestion. They don't break down in the gut but continue to bind with carbohydrates, which can cause problems. Most doctors don't warn you about lectins because most lectins never make it to the intestine, being easily destroyed by cooking. We rarely eat the foods richest in lectins — legumes and grains — without cooking them first.

If lectins make it to your gut in an active state, they may bind with intestinal membranes, disturb the gut microbiome, and damage the mucus lining of the intestine. Specific lectins are even more dangerous:

• Raw or undercooked kidney beans contain a lectin that causes clumping of the red blood cells. This lectin also causes intestinal problems, including nausea, vomiting, and diarrhea. Even tiny amounts of raw beans can cause severe issues. 
• Castor beans contain a potent lectin called ricin, which can be processed into a lethal poison for which there is no antidote. Castor beans aren't actual beans and are not used as food, although they are used to make castor oil. Poisoning from swallowing whole castor beans is rare, but chewing them up releases the toxins and could be dangerous or even fatal.

Some doctors and authors use these isolated instances to bolster their claims that lectins are harmful. They also claim that lectins cause chronic inflammation and can lead to autoimmune disease. These claims are usually based on animal studies or lab experiments rather than on clinical trials with humans. Research with human subjects has not duplicated any of these claims.

The lectins in legumes are almost all removed when soaked, boiled, sprouted, or fermented. Most cooking methods for beans, peas, and lentils involve at least one of these methods. Microwaving may not be a good method of removing lectins. Low-temperature slow-cooking also removes fewer lectins. 

Removing the hull of wheat and other grains significantly reduces the lectin content. Also, most grain products are processed and cooked before being eaten, decreasing the lectins. 

Anti-nutrients are substances that can keep the body from using certain desirable nutrients. Lectins are considered anti-nutrients because they can block the absorption of certain minerals, including phosphorous, iron, zinc, and calcium. When lectin-containing foods are soaked, cooked, or sprouted before being used, they are less likely to block significant amounts of these minerals. 

Lectins have several helpful qualities:

• They act as antioxidants, reducing the damage that free radicals can do to cells.
• They slow down the digestion of carbohydrates and may help to stabilize blood sugar.
• Early research suggests that they have cancer-fighting qualities.

The bottom line is that small amounts of lectins are good for us, although they could be harmful in large amounts. That statement is true for most of the nutrients humans need.

There are several good reasons for eating foods that contain lectins, such as legumes and whole grains: 

• Lectin-containing foods contain protein, fiber, complex carbohydrates, vitamins, minerals, and beneficial plant compounds called phytonutrients.
• They can help you maintain healthy blood pressure, cholesterol, and blood glucose levels.
• They may lower your risk of cardiovascular disease, some cancers, type 2 diabetes, and obesity. 

Still, some people might need to keep their intake of lectins low. In one study of 500 people, up to 18% reacted to lectins to some degree. If you have digestive problems after eating lectin-containing foods, reduce your use of lectin-containing foods.

Because most lectin-containing foods are cooked before they are consumed, lectins do not present a health threat to most people. If you have digestive distress after eating such foods, reduce your intake. Otherwise, there is no reason to avoid foods that provide many health benefits and are suitable for the planet.