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What are lectins

What Are Lectins? Brushing Up on These Plant Proteins

If you’ve been following this blog for a while, you are most likely familiar with dangerous lectins. They’re a key factor in a Gundry approved diet. But even with all this talk of lectins, like which foods have them and which foods are safe from them, you may wonder what are lectins, not knowing what they actually are, or why they’re dangerous to your health.

Not All “Health Foods” Are Healthy

Looking for the healthiest foods possible? You’ve probably done a lot of online research. There are the standard health foods, like fresh fruits and vegetables. But it turns out that not all these “health” foods are as good for you as they seem.

Why? Because some of them contain lectins.

Here’s a look at why each lectin you consume can ultimately damage your health, and what you should look out for if you’re interested in following a lectin-free diet.

What Are Lectins in Food – The Basics

What are lectins in food good for? Not a whole lot – unless you’re a plant. A lectin is a plant’s form of self-defense. It helps to discourage predators from eating that particular plant in the future.1

But lectins in food can poison animals and humans. One of the most powerful plant toxins, ricin, is a lectin that helps protect the castor bean plant. In fact, it’s so powerful that it has been known to seriously harm animals and humans. In some instances, ricin has even been used as a biological weapon.2

What are lectins | Gundry MD

Thankfully, the vast majority of lectins aren’t nearly as toxic as ricin. But they can still do a great deal of harm to the human body.

The Damage Lectins Can Do

You might think that since lectin is a plant protein, it’d be good for you. But a lectin is a specific type of plant protein that is actually bad for you. It binds itself to sugar molecules wherever it can find them in your body.

Whether these molecules are in your blood, digestive system, or nerves doesn’t really matter. When lectins in food latch on to these molecules, they act much like barnacles do when they attach themselves to a boat.

Turns out, if you ingest too many lectins or plant proteins, they can penetrate the cells which line your intestines.

These cells form a barrier, helping to keep harmful microbes, and other pathogens, from entering your gastrointestinal tract. When this barrier is broken, immune system problems can result. In some cases, people can experience symptoms similar to food poisoning.3

Now, lectins in food can lead to other digestive problems as well. In fact, one of the side effects of ingesting too many lectins is known as lectin poisoning. You might be wondering, “What are lectins in food, and why should I stay away from them?” Well, for one thing, lectin poisoning can lead to severe abdominal pain, vomiting, and diarrhea.4

It is a good idea to read our how to reduce or remove lectins article.

Avoid These Foods High in Lectins

It’s not enough to know the answer to the question, “What are lectins?” It’s just as important to know how to avoid them. Here are some examples of foods that contain lectins:


What are lectins | Gundry MD

While lentils and peas also have a lot of lectins, beans have more than nearly every other food. For instance, kidney beans are notorious for having high lectin content. And if you eat undercooked kidney beans, you could be at high risk for severe digestive problems.

The culprit is a specific type of lectin known as phytohaemagglutinin. If you have to eat legumes, make sure they are pressure cooked. Pressure cooking can help inactivate the damaging lectins.6


Grains are a staple of many diets. But they are chock full of potentially damaging lectins. Wheat germ, for example, contains a lectin known as agglutinin.7 If possible, try to cut down on your grain intake.


You might ask, “What are lectins doing in milk?” Even though milk obviously doesn’t come from a plant, the cows producing it eat plants. The milk from many cows contains a protein very close in structure to the casein A1 lectin. Research shows when your body converts casein A1 into beta-casomorphin (another kind of protein), pancreatic damage can result.8

Vegetables and Fruits

what are lectins | Gundry MD

Unfortunately, many vegetables and fruits are filled with lectins. The lectins in fruits are mainly found in their peels and seeds. So when you eat fruit, discard all of the seeds and peels. And make sure you only eat fruit when it’s in season.

As far as vegetables are concerned, the main culprits are so-called “nightshade” vegetables. These include tomatoes and potatoes.9

Again, most of the lectins in these vegetables are found in the peels and seeds. Why are they known as nightshade vegetables? The answer is uncertain. One theory is they usually grow at night and are typically found in shaded areas.

Lectin-Free Foods

Plenty of great-tasting foods are not just low in lectins, they’re actually lectin-free. Here are a few:

Avocados You might think of the avocado as a vegetable, but it’s actually a fruit. However you label it, you can feel 100 percent comfortable eating it – as long as you make sure it’s ripe. Not only are avocados lectin-free, but they’re also packed with antioxidants. Avocados are also high in good fats and fiber.10

Broccoli – Not all vegetables have lectins. Broccoli, cauliflower, and Brussels sprouts are also lectin-free. Asparagus, celery, garlic, and onion are a few others.

Olive oil – Olive oil is filled with minerals and vitamins that are crucial to your health. These include calcium, iron, potassium, vitamin E, and vitamin K. Olive oil has also been shown to help boost the immune system.11

One Last Thing

Now you know the answer to the question “What are lectins in food?” More importantly, you know why you need to avoid them.

By avoiding lectins in foods you eat, you can help avoid issues like a digestive upset. Just make sure you speak with your doctor first before you make any sudden, substantial changes to your diet.

Disclosure: The GundryMD team creates these articles as a way to provide you with the latest information on health and nutrition. Unfortunately, we cannot make specific product recommendations for our website visitors, such as “Total Restore” or “Lectin Shield.” Please consult with your healthcare provider to determine the best products for you.

Learn More:
5 Ways Your Body Deals with Lectins Naturally
5 Ways to Reduce or Remove Lectins From Your Favorite Foods
5 Delicious Lectin-Free Mexican Food Recipes


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