Curated by Dr. Alexander Jimenez
Lectins can be a common and hidden source of health problems and weight gain, even if you eat an otherwise healthy diet. Lectins have been linked to autoimmune reactions and inflammation, and many are toxic to your cells and nerves. Certain types of lectins may increase your blood viscosity, interfere with gene expression and disrupt your endocrine function.
If you are dealing with an autoimmune disease, you will need to be especially careful with lectins, and you may benefit from a lectin-restricted diet. That said, it is nearly impossible to avoid lectins 100 percent of the time. I do not recommend a lectin-free diet simply because you’d miss out on antioxidants and other nutrients in lectin-containing foods, including many otherwise nutritious vegetables. A better approach is to consume lectins occasionally and pay attention to how they affect you.
If you consistently experience bloating, gas and joint pain after eating beans, for example, your body may be reacting to the lectins. How you prepare lectin-containing foods makes a big difference in your body’s ability to handle them, and using a pressure cooker is by far the best approach. If you’ve been eating a whole-food diet yet find yourself struggling with unexplained weight gain and/or stubborn health problems, it might be time to limit the lectins.
What Are Lectins?
Before I continue, it is key to understand what lectins are. Lectins are sugar-binding plant proteins that attach to your cell membranes. They are a form of protein found in all kinds of plants and animal foods, which some consider to be a low-level toxin. Lectins provide a built-in defense mechanism that triggers a negative reaction in predators, aiding in their survival.
Precision Nutrition shares some additional information regarding lectins:
“Lectins are abundant in raw legumes and grains, and most commonly found in the part of the seed that becomes the leaves when the plant sprouts, also known as the cotyledon, but also on the seed coat. They’re also found in dairy products and certain vegetables.
Lectins in plants are a defense against microorganisms, pests and insects. They may also have evolved as a way for seeds to remain intact as they passed through animals’ digestive systems, for later dispersal. Lectins are resistant to human digestion and they enter the blood unchanged.”
According to Healthline, “The ‘stickiness’ of lectins makes them prone to attaching to your intestinal wall. This is the main reason why excessive lectin intake causes digestive distress.” High levels of lectins are found in beans, grains and legumes, as well as dairy and vegetables within the nightshade family. Many other foods contain lectins, at lower and less potentially toxic amounts.
Learning How Lectins Can Harm Your Health
Because they resist digestion, lectins act as “antinutrients,” which means they have a detrimental effect on your gut microbiome by shifting the balance of your bacterial flora. One of the worst culprits is wheat germ agglutinin (WGA), which is found in wheat and other seeds in the grass family. I consider Dr. Steven Gundry, author of the book “The Plant Paradox: The Hidden Dangers in ‘Healthy’ Foods That Cause Disease and Weight Gain,” to be one of the best sources of information regarding how lectins can harm your health.
He suggests some plant lectins can contribute to leaky gut by binding to receptor sites on your intestinal mucosal cells, thereby interfering with the absorption of nutrients across your intestinal wall. Due to their negative autoimmune and inflammatory effects, lectins are particularly toxic to anyone dealing with an autoimmune disorder.
By mimicking proteins in your thyroid or joint spaces, lectins can trick your body into attacking your thyroid gland and contributing to rheumatoid arthritis. Part of this disease process results in lectins and lipopolysaccharides (also known as endotoxins) penetrating your gut wall, causing a strong immune response.
Should You Avoid Beans and Other Lectin-Rich Foods?
If you are struggling with an inflammatory or autoimmune condition, you may be among those who need to be careful with respect to lectin-containing foods — specifically beans and legumes, grains and nightshade vegetables. I perform serum lab testing to determine the sensitivities and inflammation my patients have. Doing this allows me to understand the reactions their body has to specific foods, such as nightshades, and create a custom protocol to eliminate their inflammation and discomfort.
Are All Lectins Bad for You?
Precision Nutrition states: “Lectins are thought to play a role in immune function, cell growth, cell death and body fat regulation.” It seems most problems arise from overconsumption or continued consumption, even in small amounts, of certain lectins your body simply cannot tolerate.
From my perspective, it would be a mistake to assume all lectins are bad for you. One of my favorite foods, avocados, contain the lectin agglutinin (persea Americana agglutinin), but I continue to eat them regularly and would not consider them to be a food to avoid. Avocados are a healthy food, and research indicates the agglutinin found in them is devoid of specificity for carbohydrates — it interacts with proteins and polyamino acids instead.
Although tomatoes, as part of the nightshade family, are often listed among the most problematic lectin-containing foods, the heat of cooking them brings about some positive benefits. The antioxidant lycopene in tomatoes has enhanced bioavailability from heating, making tomatoes healthy in other ways. Bean lectins, however, are accompanied by more potentially toxic or allergenic effects. Beyond their lectin content, beans also are high in net carbs.
For this reason, they are best avoided in the initial transitional stages of a ketogenic diet. As you can see, the choice for or against lectins hinges on the particular food in question and the effects lectins have on the eater. While a good deal of controversy has been stirred, the presence of lectins is by no means a sole determinant of the overall value of a particular food to your diet.
The Most Damaging Lectins to Avoid
Grains and legumes such as black beans, kidney beans, lentils, lima beans and soybeans contain the highest amounts of lectins. Additional potentially damaging lectin-containing foods are:
Dairy products, especially those originating from grain-fed animals
Legumes — all beans, peanuts and soy
Nightshade vegetables, including eggplant, potatoes and peppers
Wheat and other seeds of the grass family, such as barley, buckwheat, corn, millet, oats and rye
Most lectins are proinflammatory, meaning they trigger inflammation and create advanced glycation end products.
Ways to Cut the Lectin Content in High-Lectin Foods
After eliminating the worst offending high-lectin foods from your diet, you can further reduce lectins in your diet with the following tips:
Peel and deseed your fruits and vegetables. The skin (or hull) and seeds tend to contain the highest amounts of lectins. For example, you’ll want to remove the seeds from peppers and tomatoes prior to eating them.
Choose white grains over brown. If you want to avoid lectins, the best way to safely eat bread is by choosing organic grains and then using yeast or sourdough, which effectively breaks down the gluten and other harmful lectins.
Sprout beans, grains and seeds. Sprouting deactivates lectins, although there are exceptions. Do not sprout legumes; but the lectin content is actually enhanced when sprouting alfalfa.
Eat fermented foods. Fermentation effectively reduces harmful lectins, and all sorts of vegetables can be fermented, thereby boosting their health benefits.
Why You Should Limit, Not Eliminate, Lectins
Some researchers, like Anthony Samsel, believe the lectin damage is related to their glyphosate contamination. Gundry and others make a strong case against lectins due to their potential to wreak havoc on your health. Given the number of lectin-containing foods, however, it would be nearly impossible to eliminate them from your diet entirely. The list of lectins within the vegetable kingdom alone is lengthy, and some lectins do have health benefits.
Many lectin-containing vegetables also contain polyphenols, which are micronutrients with antioxidant activity that play an important role in preventing and reducing the progression of cancer, diabetes, heart disease and neurodegenerative conditions. Polyphenols are also regarded as prebiotic, increasing the ratio of beneficial bacteria in your gut, which is important for disease prevention and weight management.
While you don’t want to miss out on the polyphenols, it’s well worth your time to experiment and identify lectins that may be problematic for your body or have diagnostic testing done to determine which lectins are effecting your system the most. Particularly if you are eating a healthy, whole-food diet but continue to have health problems, it may be time to limit the lectins. Such a change might possibly be the key to improved health and healing.
Lectins are found in many foods and do not have to be completely avoided. However, if you are struggling with an autoimmune disease, I highly recommend limiting the number of lectins you ingest. The most problematic lectin-containing foods are beans, grains, and nightshades. In addition to this, there are ways to make lectins safer to eat by properly soaking and cooking them to limit the inflammation and damage they cause to the body. – Dr. Alexander Jimenez
References: 1 Bulletproof.com, Revenge of the Beans 2, 9, 17, 18, 22 Precision Nutrition, All About Lectins: Here's What You Need to Know 3 Healthline April 1, 2015 4 Authority Diet, Dietary Lectins: What Are They and Should You Be Concerned? 5, 8 My Domaine June 25, 2017 6 Krispin.com October 18, 2017 7 Gundry MD May 23, 2017 10 Carbohydrate Research February 1980; 78: 349-363 11 Critical Reviews in Biotechnology 2000; 20(4): 293-334 12 Krispin.com October 18, 2017 13 Superfoodly October 8, 2017 14, 15, 16, 19 Gundry MD May 23, 2017 20, 21 U.S. Food and Drug Administration August 20, 2015 23 Youngmeagher.com, InstaPot Review 2017 24 Today's Dietitian September 2012; 14(9): 22 Visit www.FunctionalMedicineUniversity.com