• By Liza Torborg

Mayo Clinic Q and A: What are dietary lectins and should you avoid eating them?

September 14, 2018

a young woman in a kitchen, leaning over an open soup pot, smelling the aroma and preparing to take a taste from a wooden spoonDEAR MAYO CLINIC: I keep reading about weight loss and other health benefits from a diet where people eliminate lectins. Is there any truth to the claim that a lectin-free diet can cure autoimmune diseases and other health problems?

ANSWER: No scientific evidence exists to show that eliminating dietary lectins will cure any medical disorders or conditions, including autoimmune diseases. But your diet certainly can have an effect on the way you feel, especially if you have a chronic condition. If you have a medical concern triggering symptoms that seem to be related to the foods you eat, consider talking with a registered dietitian, who can review your diet and offer suggestions for modifying it in a way that may help ease your symptoms.

Lectins are naturally occurring proteins that are found in most plants. Some foods that contain higher amounts of lectins include beans, peanuts, lentils, tomatoes, potatoes, eggplant, fruits, and wheat and other grains. Lectins serve a protective function for plants as they grow. They don't have any nutritional value when consumed in foods.

Some research seems to indicate that taking in large quantities of raw lectins could have negative health effects. The amount you’d need to consume each day to get to that level, however, is much higher than a typical diet would include. And studies have shown that lectins break down when processed or cooked, so the risk of adverse health effects arising from lectin-rich foods that aren’t raw is not cause for concern.

In addition, most foods that contain lectins are recommended as part of a healthy, well-balanced diet. There’s a well-established body of scientific evidence that clearly supports the benefits of a diet rich in fruits, vegetables and whole grains. The health benefits you receive from including those foods in your diet outweigh any perceived benefits from avoiding foods with lectins. With that in mind, a diet that avoids lectins is not one most dietitians would typically recommend.

Also, if you’re eating a diet that includes a variety of foods and you’re having symptoms that make you feel unwell, it often can be difficult to pinpoint the specific source of the problem on your own. It could be an allergy or a food intolerance, or it may not be related to your diet at all.

If you’re in that situation, consider working with a registered dietitian, or a health care provider and a dietitian team, to sort out the cause of your symptoms. Some medical centers have dietitians that specialize in gastrointestinal issues, and those professionals can be particularly helpful in these kinds of cases.

A dietitian may recommend, for example, a short-term elimination diet, excluding certain categories of foods that tend to cause allergic reactions most often. Once those foods have been taken out of a diet, they then can carefully be reintroduced in an effort to identify possible causes of food-related symptoms. Based on that or on other evaluations, a dietitian then can make recommendations that fit the situation.

Rather than using a generalized approach and trying to apply it to everyone — such as avoiding all food with lectins — a diet that’s structured and overseen by a dietitian and based on scientific evidence can be customized to accommodate a person’s individual sensitivities. That type of systematic approach typically yields better long-term results than just avoiding a certain kind of food or a food ingredient and hoping to feel better. — Katherine Zeratsky, R.D., Endocrinology/Nutrition, Mayo Clinic, Rochester, Minnesota

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