What Are Lectins – And Do You Need To Avoid Them?

photo credit: shutterstock

What are lectins?

They’re plant proteins, and they serve as part of a plant’s defense system. “Plants don’t want to be eaten and they don’t want their seeds eaten,” explains Dr. Steven Gundry, author of The Plant Paradox. “They can’t run or hide, so they rely on these sticky lectin proteins to paralyze insects.”

In people, the potential damage from these plant proteins is more subtle, claims Dr. Gundry: “Lectins bind to sugars on the walls of the intestines.” (These sugars can also be found in the mouth, nose, and saliva.) “In the gut, lectins flip a switch that creates a space between intestinal cells, allowing bacteria and lipopolysaccharides (LPS) to cross the gut wall,” he explains. Once these things breach the gut wall, they can enter the bloodstream and potentially trigger bad reactions throughout the body, says Dr. Gundry.

Where are lectins?

Lectins are found in beans, peas, lentils, nuts, squash, nightshade vegetables (eggplant, peppers, potatoes, and tomatoes), whole grains (especially whole wheat), dairy, and eggs, Dr. Gundry says. And that explains why the idea that lectins are dangerous doesn’t sit well with many nutritionists. Check out these 11 things doctors can tell just by looking at you.

I thought vegetables and beans were healthy?

They are. Dana Greene, registered dietitian, speaks for the majority of nutritionists when she says it is hard enough to get most people to eat vegetables without demonizing them. “This diet is all the rage, but it seems to me to be less than ideal, healthwise.”

“The fear of lectins and fear of eating beans will hurt the health of the population,” warns Dr. Joel Fuhrman, a family physician specializing in nutritional medicine and author of several books including Eat To Live: The Amazing Nutrient-Rich Program for Fast and Sustained Weight Loss. Here are 10 things doctors secretly wish they could tell you.

Lectins and leaky gut

So what’s the case against lectins? It starts with something called leaky gut syndrome (increased intestinal permeability): When lectins create those spaces in the intestinal wall, partially digested food, bacteria, viruses, and toxins can pass through, says Dr. Gundry. “Our gut has an extensive border to defend it, and if we have intruders trying to come across the border, our immune system sounds an alarm that we are being invaded,” Dr. Gundry says. Your body mounts an attack to repel the invaders, and this leads to inflammation. The symptoms of leaky gut syndrome may include constipation, regular diarrhea, gas, and bloating.

The bigger issue, explains Dr. Gundry, is that when your body is under constant attack—every time you eat lectin-rich foods—the inflammation becomes chronic and can lead to an autoimmune disease: Your immune system begins to attack healthy tissues. “Your defenses become confused and engage in friendly fire elsewhere in the body,” he explains. Here’s your healthy gut diet plan.

Lectins and heart disease

Lectins are a major driver of the immune system’s attack on blood vessels, Dr. Gundry says. In one of Dr. Gundry’s studies, he put 200 adults between the ages 51 and 86 with risk factors for heart disease (including blood vessel dysfunction), on a low-lectin diet of leafy greens, fish, olive oil, and grass-fed beef, and he had the heart patients take “anti-aging” supplements such as polyphenols from fish oil, grape seed extract, and vitamins. After six months, the diet-plus-supplements regimen reversed blood vessel dysfunction in more than 50 percent of the heart patients. How old is your heart? This online test can tell you.

Lectins and autoimmunity

In autoimmune diseases like lupus or rheumatoid arthritis (RA), the immune system misfires against the body’s healthy tissues and organs. The theory is that lectins essentially provide targets for the immune system. In another study authored by Dr. Gundry, 102 patients with autoimmune disease cut lectins from their diets; within six months, 94 percent were cured, in remission, biomarker negative, and off of all immunosuppressant medications, Dr. Gundry says.

Related: What’s causing your stomach ulcer?

Lectins and weight gain

Lectin disrupts leptin, the hormone that signals the brain when you’re full: The plant substance binds to leptin receptors, taking the hormone out of commission. Your brain never gets the message that your gut is full, and this leads to overeating and, of course, weight gain. Here’s why you should increase your fibre intake, stat.

Lectins and brain diseases

“There is very strong evidence that Parkinson’s disease is, in part, driven by lectins climbing up the vagus nerve to the brain,” he says. Some studies support this theory, including a report in The FASEB Journal and a presentation at the American Gastrointestinal Association’s annual meeting. “Alzheimer’s disease and other forms of dementia may stem from a leaky gut, as well,” Dr. Gundry says.

Lectins and celiac disease

Many people with celiac disease can’t eat gluten because their body has an allergic reaction to the substance, leading to chronic digestive trouble. When patients eliminate gluten from their diets, some of them improve while others don’t, or not as dramatically. Dr. Gundry believes lectins may be to blame: “Most gluten-free products still have lectins,” he says. “It’s not just gluten—which is a lectin—that is the problem for these individuals,” he says. “If you take out all of the lectins, all of their symptoms will resolve.”

Related: 14 health myths even doctors believe

Should I be concerned about lectins?

Some people may be sensitive to lectins, and these individuals could potentially benefit from a diet that is low in lectin, Dr. Fuhrman says. “It’s a relatively low percentage of people who fall into this category and we have to identify them first,” he says. If you have chronic stomach problems or an autoimmune condition, talk to your physician about a short-term lectin elimination trial. Here’s how to tell if you might have a hidden thyroid problem.

What about vegetarians?

Vegetarians and vegans, in particular, eat diets that are heavy in lectins, Dr. Gundry says. “I am not anti-vegetable.” There are ways to eat vegetables without lectins, he explains: “If you peel nightshade vegetables and remove the seeds, you remove the lectins.” What’s more, soaking beans overnight in a baking soda bath and pressure cooking them also reduces lectins, he says. Fermenting fruits and vegetables works too. Fermented foods have other health benefits too.

One lectin everyone should avoid

It’s a mouthful: Phytohemagglutinin—found in raw beans, and red kidney beans, in particular—binds to a carbohydrate present on human intestinal cells and can cause severe nausea and vomiting. This lectin is inactivated by cooking. “If you use dry beans, take the necessary precaution of making sure they are thoroughly cooked,” Dr. Fuhrman says. “Don’t eat undercooked beans. Raw beans can be toxic, and this is why we soak them overnight and cook them.” Have you heard about adaptogens? Learn why these superherbs are attracting so much attention in the wellness world. 

A final word about lectin-free diets

This approach to eating will do more harm than good for the majority of people, stresses Dr. Fuhrman. “Plant lectins have powerful anti-cancer effects,” he says. “Beans are the highest in lectins,” he explains, “and an arm of the Nurse’s Health Study found that women who ate the most beans had the lowest risk for breast cancer. Tomatoes are also a major source of lectin, but they protect against prostate and breast cancer,” he says.

Next, don’t miss 12 silent signs your body needs more carbs.