Until recently, few people gave much thought to lectins, a naturally occurring plant compound. But as the T. Colin Campbell Center for Nutrition Studies chronicles, the 2017 book The Plant Paradox, by Dr. Steven Gundry, has caused readers to consider the lectin avoidance diet. Is it right for you?
Unpacking the Lectin Quandary
Different types of lectin proteins are found in different plant categories. While the categories of lectins in the foods you eat vary depending on food categories — for example, legume lectins and grain lectins — they share the quality of being proteins that bind with carbohydrates.
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Gundry's book contends that lectins themselves are toxins that cause inflammatory reactions. These reactions can range from weight gain to digestive problems and certain chronic diseases, according to Gundry's book. He recommends avoiding foods high in lectins, in favor of lower-lectin substitutes.
The T. Colin Campbell Center for Nutrition Studies notes that a lectin avoidance diet includes legumes, like dried beans and lentils, as well as grains. Another food group high in lectins is the cucurbit, or gourd, family, which comprises fruits and vegetables like winter squash, summer squash, melons and cucumbers.
The Mayo Clinic further lists tomatoes, eggplants and potatoes — the so-called "nightshade" family. (Sweet potato lectin content is less of a concern because it doesn't fall into these categories.)
Read more: List of Foods that Contain Lectin
Understanding the Lectin Avoidance Diet
Lectins aren't, strictly speaking, a nutrient — at least for humans. Lectins are proteins found within plant tissue that are believed to help plants fend off diseases and pests. Botanists have found evidence that damage to the plant, such as a fungal infection, seems to create a flush of new lectins to fight off the existing threat. Some plants that rely heavily on nitrogen, including beans and other legumes, use lectins to help make soil nitrogen more available to the plant's roots.
But, as the Mayo Clinic points out, lectins don't provide any known benefits to people who eat foods that are high in these proteins. Their only benefit to your health, in other words, is an indirect one. They are one of several factors that keep edible plants healthy long enough to mature into harvest-ready plants.
Yet it's important to note that if you pursue a lectin avoidance diet, you won't just be cutting lectins out of your life, but also all the nutrients that lectin-rich foods provide to humans. In effect, you'll either need to reconsider starting a lectin avoidance diet or figure out food substitutes and cooking methods that cut out lectin while still giving you a well-rounded eating plan.
Should You Go Lectin Free?
According to the Mayo Clinic, there's limited evidence that a lectin avoidance diet is key to better health. It definitely has not been shown to actually cure chronic health conditions. These include autoimmune diseases where foods known to cause inflammatory responses don't seem to be connected to their lectin content.
The Arthritis Foundation lists a range of ingredients that may cause inflammatory responses, and lectin is not currently on that list. These food groups include those high in gluten, such as bread and pasta made from wheat, rye or barley, or casein, a protein found in dairy products. Meals containing refined, rather than complex, carbohydrates can also set off inflammation responses in some people. For others, even moderate amounts of alcohol can also cause inflammation.
Avoiding white potatoes, white bread and pasta can help people with arthritis and other inflammation-sensitive conditions. Diet sodas and snacks made with aspartame, meals prepared with monosodium glutamate, trans fats, saturated fats and sugary foods can also cause a negative response. While omega-6 fatty acids are healthy in moderation, relying on ingredients like sunflower, peanut and vegetable oils should be avoided, notes the Arthritis Foundation.
Some of the foods known to trigger inflammation may overlap with food on the lectin avoidance diet, such as some grains and dairy products. While nutritionists believe these foods are problematic because of components like refined carbohydrates, gluten and casein, ultimately the root cause doesn't matter if eliminating or limiting makes you feel better. Having fewer portions of high-fat cheese and buttery white-flour pasta can also help you lose weight.
On the other hand, some of the foods that the lectin avoidance diet places on its "naughty list" stand in contradiction to the meal plans often recommended by medical institutions for people with autoimmune disorders or those who want a sensible weight-loss program. The Mediterranean diet is frequently cited as a healthy one in these instances. This diet is rich in beans, grains and a wide range of fruits and vegetables.
Not sure whether to cut staples like beans, grains, and certain fruits and veggies from your diet? The Mayo Clinic suggests visiting a nutritionist to help you identify whether you do have a sensitivity to lectins and to discover potential food replacements to make sure you still get the nutrients you need.
Read more: Types of Beans That Cause Excess Gas
Dealing With Legumes
The legume group contains some of the highest levels of lectins, but also some of the best sources of dietary nutrients. Foods in this category include dried beans, like kidney, chickpea and pinto beans, as well as lentils, green peas and peanuts. Most are rich sources of protein, fiber, B vitamins and minerals.
If you cut legumes out altogether as part of your lectin avoidance diet, it's important to make up for their nutrients with other foods. Few pack the "all in one" benefits of legumes, however, so it will take more than one food group.
For proteins, consider eggs, fish, chicken and lean red meat, many of which also provide vitamins and minerals. Fiber can be a bit more difficult to include, especially if you're also avoiding high-lectin foods like grains, but adding more fruits and vegetables to your diet can help.
Cooking and processing do help break down lectin content, according to the Mayo Clinic. Unless you believe you're extremely intolerant of lectin content, consider making a few changes that allow you to keep legumes in your diet. Rather than making cold bean dip from canned chickpeas, for example, focus on further cooking those canned beans in hot dishes such as chili or soup. Instead of eating fresh peanuts as a snack, switch to peanut butter.
Cucurbits are also high in lectins. Fortunately, other fruits and vegetables provide many of the nutrients contained in squash, cucumbers and melons. If you’re trying a lectin avoidance diet, eat a “rainbow” of colors to get the antioxidant protection you need. The sweet potato's low lectin content, for example, can make up for nutrients lost by giving up other yellow and orange produce that's higher in lectins.
Considering Going Grainless?
Foods like rice, quinoa, barley, pasta, bread and cereal can be highly nutritious. The key is to eat those made from whole grains, rather than those which have been refined. The grain food group is a rich source of fiber, B vitamins and minerals.
Your nutritionist may suggest trying to eliminate certain types of grains, rather than eliminating all of them. Your sensitivity or weight-loss struggles may stem from gluten intolerance, not a lectin issue, for example. In that case, focusing on rice and gluten-free bread, as well as cornmeal, buckwheat and quinoa-based meals, may help provide nutrients while avoiding the side effects of gluten.
If you do need to avoid grains altogether because of lectin content, it's important to replace the nutrients they provide. Make sure to eat plenty of fruits and vegetables for fiber, especially those with edible seeds or peels. Leafy, green vegetables, fish and eggs can provide a range of B vitamins and minerals, such as iron.
- T. Colin Campbell Center for Nutrition Studies: "What Are Lectins? A Look at This Controversial Protein"
- International Food Information Council Foundation: "The Low-Down on Lectin"
- Mayo Clinic: "What Are Dietary Lectins and Should You Avoid Eating Them?"
- Cornell University College of Agricutulture and Life Sciences: "Plant Lectins"
- Arthritis Foundation: "8 Food Ingredients That Can Cause Inflammation"
- Arthritis Foundation: "Anti-Inflammatory Diet"
- American Heart Association: "Eating the Rainbow"
- USDA ChooseMyPlate: "Why Is It Important to Eat Grains?"
- Academy of Nutrition and Dietetics: "What Are B-Vitamins?"
- Academy of Nutrition and Dietetics: "Iron"
- American Heart Association: "The Benefits of Beans"