What Really Happens When You Eat Foods High in Lectins

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If you lurk on social media long enough, you’re bound to find a post that warns you off eating foods high in lectins. Now, while lectins are often disparaged as “anti-nutrients” and may sound vaguely sinister if you say “lectins” slowly enough, they are actually natural substances found in about 30% of the food commonly eaten in the U.S., including grains, fruits, vegetables, nuts, seeds and legumes.

“Dietary lectins are a family of proteins that bind to carbohydrates,” explains Ali Segersten, CN, a functional nutritionist and author of Nourishing Meals: Health Recipes & Meal Planning for Your Unique Diet. In plant foods, lectins can act as part of the host defense system, protecting the plant from being eaten by animals and insects.” The same structure that makes them protective of those plants can also make them resistant to digestive enzymes, says Amy Shapiro, RD, CDN, the founder of Real Nutrition in New York, “so these reach the gut intact.” On the other hand, lectins slow down the absorption of food, so they can be helpful for stabilizing blood sugar.

In theory, these undigested proteins can lead to issues such as nausea, vomiting, upset stomach and diarrhea. Some books and social media posts have also linked lectins to chronic inflammation and obesity. However, for most people, “there is not yet any substantial scientific evidence to support the need to limit or avoid lectins,” Shapiro says.

The good news about dietary lectins is that even the foods that have the highest amounts can be safely eaten simply by cooking them. “Traditional methods of preparing foods, such as soaking, sprouting and fermenting, all greatly reduce the levels of lectins in foods,” says Segersten. By cooking or soaking the foods, you turn active lectins (what is found in raw plants) into inactive lectins. And since lectins have no nutritional value on their own, there's no need to worry that you're losing a valuable part of the food.

Here, a list of high-lectin foods and how to prepare them:

Red Kidney Beans

Red kidney beans are an excellent plant-based source of protein and fiber, however, it is essential to soak and cook them properly, the experts say. That's because in their raw form, kidney beans have high levels of lectins, and can cause dietary discomfort. However, once they're soaked and cooked, the lectin count goes down. If you're cooking up a pot of chili with kidney beans, either use canned beans, which have been cooked and stored in liquid and are lower in lectins, or be sure to soak raw beans in water for at least 8-12 hours before cooking and then boil for at least 30 minutes to destroy the lectin, Shapiro says.

RELATED: How to Cook Dried Beans the Traditional Way

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Whole Grains

Whole grains such as oats, barley, quinoa and brown rice are an essential part of a healthy diet, and are associated with lower rates of cardiovascular disease and type 2 diabetes. And they are also high in lectins. But unless you are grabbing a sheaf of wheat right off the farm and eating it raw, you shouldn't worry, since by the time you eat these grains, they will have been thoroughly cooked, reducing the lectin count.

RELATED: Healthiest Whole Grains to Add to Your Grocery List

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Everyone's favorite salty snack is another source of lectins —however, when the nuts are roasted (as they are in most peanut butters and commercially available jars of nuts), the lectins are reduced. If you're worried about lectins, simply avoid any raw peanuts.

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Tomatoes, along with eggplant and peppers, are part of a food group called nightshades, which tend to be higher in lectins. But in tomatoes, much of the lectin content is found in the seeds and skin. "For those very sensitive to lectins, removing the seeds from tomatoes, reduces the amount of lectins consumed," says Segersten. Since cooking reduces the lectins as well, Shapiro recommends making sauces or soups that simmer for a long time to bring the lectin count down even further.

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Another delicious plant-based source of protein and fiber, lentils are high in lectins only when eaten raw, but perfectly harmless when soaked and cooked, as you would when preparing them for soups and stews.

RELATED: Tasty Lentil Recipes for Healthy and Easy Weeknight Meals

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Potatoes — a staple of so many diets — also contain lectins, especially in their skin. If you're concerned about lectins affecting your digestion, peel potatoes before you cook them, and bake or boil until soft, says Shapiro.

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Lectins make up about 10% of the protein in soybeans, the versatile bean that is beloved by vegans and vegetarians around the world. Thankfully, the process of boiling the beans eliminates the majority of lectins. And since soy has so many health benefits, from reducing the risk of breast cancer to preventing bone loss, it's worth keeping them in your rotation.

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Eggplant is another healthy vegetable that happens to be high in lectins, but as with all the other foods on this list, they can be reduced by cooking.

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What are the symptoms eating of too much lectins?

Most experts say that lectins do far more good than harm, and you would have to eat excessive amounts of uncooked beans, for example, to get to a point where the lectins could hurt you.

The exception may be people with leaky gut, autoimmune conditions, irritable bowel syndrome, Celiac disease and other chronic health conditions, who may be more reactive to dietary lectins, says Segersten.

Gastrointestinal symptoms, including abdominal pain, vomiting and diarrhea would be the most common.

If you are concerned, she recommends trying an elimination-type diet in which high-lectin foods are avoided for a short period of time, then reintroduced one at a time to see if they are contributing to your symptoms. Keep in mind, an elimination diet should only be done under medical supervision by a doctor or dietitian.

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The bottom line

Unless you have a very specific condition that makes you sensitive to lectins, go ahead and enjoy them, but be sure to cook them properly. The vegetables and whole grains that are high in lectins also happen to be foods that are high in essential nutrients that are crucial for overall health, points out Shapiro, who adds, “consuming a variety of foods in your diet ensures a balanced intake of nutrients that will ultimately minimize the potential adverse effects from lectins.

Segersten is also skeptical of the anti-lectin sentiments seen on social media. “If we look at the dietary patterns found in the Blue Zones — places in the world where humans are living healthy to 100 years of age — we see that their diets are made up of mostly plant foods full of various lectins,” she says. “In fact, most of these cultures consume 80 to 90% of their diets in plant foods.”

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