Lectin-Free Diet: Good or Bad for IBD?

Lectins have gained recent popularity by proponents of the paleo diet. These “anti-nutrients” are claimed to be harmful or even toxic, yet they’re found in many health food staples such as legumes and grains. Are lectins something that should be avoided with an IBD gut or can preparation methods eliminate the dangers? 

What are lectins?

Lectins are carbohydrate-binding proteins that help molecules stick together. They’re thought to act as a natural insecticide and plant defense mechanism [1]. When consumed in small amounts, they have several health benefits but when eaten in large amounts, they may interfere with absorption of other nutrients which is why they get the name “anti-nutrients”. Some studies have found that lectins can interfere with calcium, iron, phosphorus, and zinc [2].


Lectins are found in these food sources:

  • Nightshade vegetables (eggplant, peppers, potatoes, tomatoes)
  • Legumes (especially soybeans, red kidney beans, and peanuts) 
  • Whole grains
  • Dairy 


Some foods that are commonly associated with IBD symptoms are similar, including dairy, grains, and legumes [3] but few human studies result in a definitive claim regarding the relationship between lectins and IBD. 


Lectins in your intestine 

Lectins resist being broken down in the gut and are stable in acidic environments [2]. They have binding properties that may cause nutrient deficiencies, disrupt digestion, and cause intestinal damage, especially if you’re prone to digestive issues or have less enzyme production [3]. 


Some people suggest that lectins cause increased gut permeability, called leaky gut, which can potentially lead to autoimmune diseases. When too many lectins are consumed, it can signal to your gut to empty the contents; similar to having too much alcohol or bad bacteria. 


When something irritates the gut lining, it can lead to a more broad immune system response. Symptoms related to gut issues include skin issues, joint pain, and general inflammation [4]. In IBD, the gut lining is more sensitive in general. This may lead to more complications and symptoms with lectins. 


Consuming legumes and grains raw, can even result in diarrhea, vomiting, and nausea [5]. However, it’s important to note that this is when they’re in the raw form. When lectins are prepared properly, most of the lectins can be removed. 


How to limit lectins 

Something to consider is that eating too much of anything may cause your body to negatively respond. Variety can help increase the amount and type of nutrients you get, decrease exposure to any one pesticide, and decrease the likelihood of overexposure to lectins. 

Soak them

Soaking involves putting raw, dried, or preserved foods in a liquid in order to soften the food. In general, the longer the sprouting period, the more the lectins are deactivated. When you soak, aim to do so overnight and change the water. Drain and rinse them again before cooking. In addition to soaking, adding baking soda can also help neutralize the lectins.

Cook them 

Eating foods with high amounts of active lectins is rare because lectins are most potent in their raw state. Cooking, especially with wet and high heat methods can inactivate most lectins. Boiling legumes in water eliminates most lectin activity. This is because lectins are water-soluble and typically found on the outer surface of a food so water can remove some of them [1].

Ferment them 

Fermentation allows naturally occurring helpful bacteria to break down some substances in food, making them easier to digest. Fermenting foods can decrease lectins and other anti-nutrients. Friendly bacteria can reduce lectins by up to 95% [6].


Summary: should you live lectin free?

Lectins have gotten a bad wrap because of their anti-nutrient and toxic claims. But it’s important to consider that they’re found in a lot of healthy, plant-based foods. They can act as an antioxidant, protect your cells from damage, decrease inflammation, and even slow the absorption of carbohydrates, preventing drastic blood sugar fluctuations. 


If you think you may be suffering from a lectin intolerance, try focusing on the preparation methods of your food first. Regardless of whether you think you may have a lectin sensitivity or not, properly cooking food can be helpful for digestion and absorption.


Living with IBS is complicated in and of itself because everyone is different. You’re unique and know your body best. At Nori we encourage you to be your own food detective, seeking out the culprits of your IBD symptoms and discovering ways to substitute them in your diet. 


This article has been written by Lisa Booth, registered dietitian and nutritionist, and co-founder of Nori Health. Content is based on her professional knowledge, and our collection of 100+ scientific research study papers.