What Is the Lectin-Free Diet? (2024)

You may not have heard of the "lectin-free" diet, but you probably know people who avoid eating legumes, whole wheat and nightshades because they're trying to avoid lectins.

But what are lectins? And should you be following a diet that restricts or eliminates lectins? That depends. Here's a little bit more information to help determine whether or not you need to be paying attention to the lectins in your diet.

What Are Lectins?

According to 2021 research published in the Journal of Biosciences, lectins are proteins that bind to other carbohydrates. They've been referred to as "anti-nutrients" because they aren't digestible in the human gastrointestinal tract and could potentially prevent your body from absorbing key minerals like calcium, iron, phosphorus and zinc.

Lectins also attach to the cells lining your intestines and can stay there for a fairly long period. Because of this, lectins have the potential to cause an autoimmune response, according to a 2020 study published in the Journal of Immunology Research—and this is, in part, what's fueled an anti-lectin movement (for proof, check out the popularity of the paleo diet and the Whole30 diet, both of which eschew many lectin-containing foods).

What Is the Lectin-Free Diet?

The lectin-free diet was developed by Steven Gundry, M.D., a former cardiothoracic surgeon at California's Loma Linda University Medical Center and the founder of the Center for Restorative Medicine in Palm Springs, California. Gundry believes lectins are responsible for numerous physical discomforts and that they may cause leaky gut syndrome—aka intestinal hyperpermeability—where holes develop between the cells lining your GI tract. When the cells lining your intestines are compromised, they can't keep inflammation-triggering toxins and bad bacteria out of your bloodstream—nor can they keep good things like nutrients in.

While some experts claim that leaky gut is caused by things like eating lectins and that this, in turn, causes conditions such as food allergies, inflammatory diseases and celiac disease, according to a 2021 review article published in Frontiers in Nutrition, there is a "chicken-and-egg question" surrounding all of this. While there does appear to be a correlation between leaky gut and certain health conditions, the research is not definitive on what causes what. Does a leaky gut cause these health conditions? Or do these health conditions cause a leaky gut? More research is needed.

Foods High in Lectins

All plants contain lectins, as do grain- and soy-fed animals, according to a 2019 review in Food and Chemical Toxicology. In nature, lectins serve as a kind of protective measure for plants, as they can be toxic to insects and act as a natural insecticide, per a 2022 review in the Glycoconjugate Journal. And since lectins aren't digestible, it would seem that foods containing lectins would also be unappealing to consumers like animals and humans. Clearly, this isn't the case, as many of the foods we regularly eat contain lectins.

That said, according to the same 2022 review, not only do lectin levels in plants vary, but there are also different types of lectins. Lectins tend to be highest in raw legumes—such as peas, beans, lentils, soybeans and peanuts—and in whole grains such as wheat.

Nightshade vegetables (eggplant, tomatoes, peppers, potatoes and seed spices), squash and fruit are also higher in lectins, which has led many lectin-free diet promoters to advocate for avoiding these foods, according to a 2019 review in Nutrients.

Foods Low in Lectins

According to Gundry, these foods are low in lectins and OK to eat on a lectin-free diet.

• Avocado
• Asparagus
• Broccoli, Brussels sprouts and other cruciferous vegetables
• Celery
• Cooked sweet potatoes
• Garlic
• Leafy green vegetables
• Mushrooms
• Onion
• Pasture-raised meats

Pictured recipe: Tomato, Cucumber and White-Bean Salad with Basil Vinaigrette

Should I Avoid Eating Lectins?

Probably not. Many health experts point out that the research is limited regarding lectins and the harmful effects of consuming what are called "active lectins" (such as those found in raw beans). We don't actually eat many active lectins because we rarely consume foods containing high amounts of lectins raw.

Soaking or sprouting high-lectin foods deactivates the lectins, as does cooking them with high heat (boiling, stewing, etc.) This is one of the main reasons we cook (and sometimes also soak) beans—raw beans are full of active lectins that will upset your stomach. Fermentation is another way to deactivate lectins, according to a 2022 review in the Journal of Functional Foods.

The benefits of eating foods that are high in lectins, such as whole grains and beans, also largely outweigh the potentially negative effects for most people. According to a 2019 study in Nutrients, legumes provide fiber, protein, magnesium and zinc, and may protect against diabetes, high blood pressure, heart disease and inflammation. And research, like the 2021 study published in Comprehensive Reviews in Food Science and Food Safety, shows that eating whole grains reduces your risk of and mortality from several chronic diseases, including cardiovascular disease, diabetes and some types of cancer.

"If you're healthy, there is no reason to be afraid of lectins. Lectins are found in foods that are tied to a reduced risk of obesity and chronic diseases, and an increase in longevity," says Cynthia Sass, RD, CSSD, a virtual plant-based performance nutritionist. "In fact, in the areas in the world where people live the longest, healthiest lives (with low rates of obesity and chronic disease), high-lectin foods are staples, including pulses and whole grains."

Some of these areas include what are referred to as "Blue Zones"—areas of the world where people live exceptionally long lives. According to a 2022 review in Maturitas, these zones include the island of Okinawa in Japan, the island of Ikaria in Greece, the mountain area of the island of Sardinia in Italy and the peninsula of Nicoya in Costa Rica.

People Who Should Consider Avoiding Lectins

If you have irritable bowel syndrome or another digestive sensitivity, you may be more likely to experience negative effects from eating lectins. Also, if you have an autoimmune condition or food sensitivities, higher-lectin foods may exacerbate inflammation, says Sass.

If you already know you have certain food-based triggers, you'll probably be better served by working with a registered dietitian to determine if you need to eliminate lectins. A dietitian can also create an individualized plan to ensure that you don't miss out on fiber and essential nutrients if you're avoiding many foods that are naturally high in them.

The Bottom Line

Unless you have a specific sensitivity to lectin-containing foods, there's no reason to cut foods with lectins out of your diet entirely. Beans, whole grains and vegetables with lectins provide many boons to our health, so barring any specific reason to avoid them, you'll reap the benefits in vitamins, nutrients and disease prevention.