A bowl full of lectins

What Are Lectins and Their Role in Stomach Problems?

Beans, beans, they’re good for the heart. The more you eat, the more you end up feeling constipated, battling bloating, and cramping in a fetal position. Legumes are an excellent source of plant-based protein. However, people with stomach problems such as Irritable Bowel Syndrome (IBS) and Leaky Gut Syndrome may have trouble digesting them due to a protein known lectin.

There are positive benefits to lectins. Therefore, if you do not have stomach problems, consume foods with this protein without caution. Although, too much of a good thing can still lead to gas in stomach! With that being said, if you do experience frequent GI issues, you may want to remove foods with lectin from your diet. Let’s learn a bit more about what might be causing some of the stomach problems you’re experiencing.

What is Lectin?

Lectins are proteins that bind two carbohydrates together. Their primary purpose is to facilitate cell-to-cell interaction 1.

All living organisms contain different types of lectins in various quantities, ourselves included. However, humans tend to have trouble with the digestion of food that has plant-based lectin.

What makes lectins so hard for those with gastrointestinal issues to digest is that they tend to hang out in hardy exteriors. That’s why they are plentiful in whole grains, seeds, and starches.

Botanists believe plants formed lectins as a means to ward off predators 2. As a cricket munches on a blade of grass, the grass releases lectin to repel the insect. Now think on a larger scale. We have a few pounds or so on a cricket. Rather than outright resisting us, lectin just causes stomach problems.

Why Do Lectins Cause Stomach Problems?

For one, lectins have chemical reactions with the carbs they touch. Plus, they altered the interaction those carbohydrates had when they both reacted with one another. Essentially, lectin left a little bit of its stank on the others’ relationship and could have left a bad taste in their mouths.

The second issue is the structure of lectins. They are too big to fit in the tight junctions of our small intestine. Now, remember how lectins bind carbs? Anytime something is a binding agent, it’s a bit sticky.

Since lectins can’t pass through the digestive system, it rubs a bit of its sticky residue off onto the villi and microvilli lining the GI tract. Villi and microvilli aren’t a bad lip-synch 90s band. They are little hairs on our gut lining responsible for nutrient absorption. Therefore, those who are sensitive to lectins may experience gastrointestinal disorders due to microvilli damage.

While lectins remain on the microvilli, they also trigger another response within the system. Lectin facilitates the production of zonulin 3.

Zonulin is a protein that modulates tight junctions, the cell barrier for your small intestine. By triggering zonulin, it causes the tight junctions to increase its permeability. Naturally, this is done to allow nutrients to seep into the system.

Unfortunately, inflammatory-inducing foods like lectins permit the tight junctions to open before food is properly digested. Therefore, toxins and whole food particles enter the bloodstream. Our body doesn’t communicate with these particles, so it causes an immune response. Long-term effects of these sort of interactions may result in conditions like Leaky Gut Syndrome.

What Foods Are Highest in Lectins?

Asking yourself what foods are the highest in lectins? These protein molecules are abundant in legumes and wheat. With that being said, there are other foods high in these proteins that might cause a sour stomach.

Foods highest in lectin include:

  • Dairy (Casein in Cheese, Milk, Yogurt)
  • Legumes (Black Beans, Chickpeas, Lentils, Peanuts, Soybeans)
  • Nightshades (Eggplants, Goji Berries, Peppers, Potatoes, Squash, Tomatoes)
  • Whole Grains (Baked Goods, Bread, Corn, Crackers)

    We know. Seems like there are lectins everywhere. However, no lectin is created equal. Therefore, keep an eye out for the following lectins to avoid further development of stomach problems.

    Which Type of Lectins to Avoid?

    Lectins are a broad term to describe proteins that have the same job title, which is binding agent extraordinaire. Just like one person in the office can be a jerk whose lunch smells up the microwave, another co-worker could be delightful and bring baked goods every Friday morning. Yeah, lectins can be on either end of the spectrum too. Here are a few lectins to avoid if you don’t want stomach problems.


    These lectins get their name because they have a high level of proline. Proline is an amino acid that is responsible for giving organisms their structure, mainly collagen 4.

    As anyone who has been filled with collagen can attest, that stuff is pretty solid. If your lips can withstand biting it, your digestive system will have trouble breaking it down.

    Prolamins is a term used to classify a combination of 71-78 proteins. Mainly, these molecules are made of gluten’s primary proteins–glutenin and gliadin.

    Protein sources under the prolamins umbrella “constitute ~80% of the proteins in the wheat grains and supply 50% of the global dietary protein demand 5.” Even gluten-free foods such as quinoa contain prolamins. This realization is alarming for those with autoimmune disorders.

    The reason those with Celiac Disease and autoimmune disease have issues involving the digestion of food with gluten is that gluten molecules look much like our own tissue. Our body perceives gluten as a target, calling immune cells to handle the situation. In fact, many immune systems have developed antibodies to attack these particles.

    Tragically, immune cells attack our own healthy cells that look like gluten. The same happens when gluten-free prolamins enter the system 6. That’s right, foods like quinoa and corn also have this problematic protein.


    Just the name alone sort of gives off bad vibes. Believe it or not, agglutinins are not members of the gluten family. However, their texture does resemble the sticky nature of gluten.

    These lectins get their name for the process of agglutination. Agglutination is the merging together of particles. Much like the ongoing theme of binding, agglutinin is the glue that holds particles together.

    Our body produces agglutinin to join red blood cells together to fight invaders. When you consume plant agglutinins, it confuses the heck out of your body.

    Once in our system, agglutinins bind onto other immune cells. This needy behavior will render your immune cells rather useless, causing you to be more susceptible to illness.

    Also, agglutinins are hard for your body to digest. They are a defense mechanism within seeds. Historically, predators (early humans) would pass seeds through their feces. That way, the grain would be back in nature and with fertilizer. Suffice to say, modern-day plumbing has put a kibosh on that survival mechanism.

    Since we can’t digest agglutinins properly, they irritate the gut lining. As a result, we experience stomach problems. Chronic inflammation caused by agglutinins may lead to Leaky Gut Syndrome and other gastrointestinal disorders.

    How to Consume Lectins With Minimal Stomach Problems

    Legumes and whole grains are excellent sources of protein. They are optimal dietary choices for those who are looking to go back-to-basics and follow a Paleo Vegan Diet.

    If you have severe food sensitivities, try cutting all lectins out. However, if the stomach problems are minimal, you can try a few approaches to help with the digestion of food with lectins.

    As we mentioned, lectin tends to hang out around the exterior. Therefore, you need to crack through the nutrients on the outside. Doing this will reduce lectin levels of the food. In some cases, the lectin levels may drop so significantly, that you may no longer experience stomach problems after eating once-troublesome foods.

    Soak Your Lectins

    If you are cooking legumes, soak them in distilled water from 30 minutes to 24 hours. The longer you soak, the softer the beans will become. For one, this will aid in the digestion of food.

    However, a majority of lectins are water-soluble 7. Therefore, many particles that cause gastrointestinal distress may stay in the water after you drain the beans.

    This complexity is what makes soy such tricky food for those with stomach problems. For instance, tofu is a healthy way to consume soy because it’s encased in water. The lectins end up in the water, making the tofu blocks easier to absorb than soy milk (which is soy and water) for people experiencing gastrointestinal issues.

    Boil Your Lectins

    Heating items up change their chemical composition. It also kills off harmful bacteria. That is why a chicken cutlet can turn from Salmonella City into a Cordon Bleu.

    When you boil your lectin-rich foods, many of the lectins will die off. Plus, boiling softens the shells. It will be easier for your body to digest the proteins and chauffeur them out of the system.

    Buy Sprouted Products

    When beans sprout, it’s sort of like the insides are pushing out. Therefore, the outer shell get metabolized. As a result, lectin levels decrease immensely in a number of problematic foods.

    However, beware of which beans you choose. For instance, alfalfa sprouts experience a surge in lectin numbers during the sprouting phase.

    Ferment Your Lectins

    Fermentation is a great way to preserve your foods. However, it transforms them into some of the best foods for gut health.

    As you ferment foods, yeast in the jar feed on the sugars of the food source. That means lectins get consumed.

    When we ferment fruits and vegetables, it creates probiotic bacteria. Regularly consuming probiotic foods can help your body process lectin.

    Buy a Microbiome Test

    If lectin is creating stomach problems, you need to get some stomach solutions. Long-term damage created by lectin may result into inflammation and the growth of opportunistic bacteria and yeast.

    To reverse some of these effects, you need to determine which bacteria are in your gut. Receive these results with a gut health test.

    With microbiome testing, you can create a clear action plan to gut health. At Ombre, we analyze your microbial DNA to provide you with a list of foods you should avoid and which you should eat to create a healthier microbiome. 

    Plus, we provide a strain-specific probiotic recommendation.  As a result, you will have more beneficial bacteria readily available. That way, if you consume too much lectin, you have the backup already in place!


    • 1 Berg JM, Tymoczko JL, Stryer L. Biochemistry. 5th edition. New York: W H Freeman; 2002. Section 11.4, Lectins Are Specific Carbohydrate-Binding Proteins.
    • 2 De Hoff, P. L., Brill, L. M., & Hirsch, A. M. (2009). Plant lectins: the ties that bind in root symbiosis and plant defense. Molecular genetics and genomics : MGG, 282(1), 1–15. doi:10.1007/s00438-009-0460-8.
    • 3 Drago, Sandro, et al. “Gliadin, Zonulin and Gut Permeability: Effects on Celiac and Non-Celiac Intestinal Mucosa and Intestinal Cell Lines.” Scandinavian Journal of Gastroenterology, U.S. National Library of Medicine, Apr. 2006, www.ncbi.nlm.nih.gov/pubmed/16635908.
    • 4 Li, Peng, and Guoyao Wu. “Roles of Dietary Glycine, Proline, and Hydroxyproline in Collagen Synthesis and Animal Growth.” Amino Acids, U.S. National Library of Medicine, Jan. 2018, www.ncbi.nlm.nih.gov/pubmed/28929384.
    • 5 Mejías, J. H., Lu, X., Osorio, C., Ullman, J. L., von Wettstein, D., & Rustgi, S. (2014). Analysis of wheat prolamins, the causative agents of celiac sprue, using reversed phase high performance liquid chromatography (RP-HPLC) and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). Nutrients, 6(4), 1578–1597. doi:10.3390/nu6041578.
    • 6 Ortiz-Sánchez, J. P., Cabrera-Chávez, F., & de la Barca, A. M. (2013). Maize prolamins could induce a gluten-like cellular immune response in some celiac disease patients. Nutrients, 5(10), 4174–4183. doi:10.3390/nu5104174.

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