In case you were thinking of reading chapter 11 of Biochemistry, 5th edition, today, I’ll save you the time. Lectins are proteins that bind to carbohydrates. They’re all over the place in nature — in plants, animals, and many kinds of microorganisms — and there are thousands of different kinds.
The word lectin comes from the Latin “legere,” meaning “to select,” because it was thought that they choose the carbohydrates to which they bind. You can think of lectins as the bumps and holes in Lego blocks, which are unrelated to the Latin word “legere” (but it would be fun if they were).
Some researchers think plants evolved lectins to protect themselves against pests and pathogens. This protective effect is similar to that of other phytochemicals, such as flavonoids, which serve as natural defenses in plants and are extremely good for us as well.
Where Are Lectins Found?
Lectins are found in a wide variety of both animal and plant foods. About 30% of the food we eat daily contains lectins.
Foods High in Lectins
Some of the foods richest in lectins include:
Looking over that list, we can see a few categories of lectin-rich foods: legumes, nuts, grains, fruits, and nightshade vegetables. While the amount of lectins in individual ingredients can vary greatly, these categories of foods generally contain high levels.
The Lectin Controversy: Why the Real Story Is More Interesting Than You’ve Heard
The primary reason there is controversy over eating lectins today is the best-selling book The Plant Paradox by Dr. Steven Gundry. The book, released in 2017, advocates a lectin-free diet.
The author claims that lectins adversely impact your gut flora — the bacteria that live in your digestive system — which can lead to a whole slew of unwanted effects. He claims that many people suffer from lectin intolerance or sensitivity, symptoms of which can include gas, bloating, nausea, diarrhea, fatigue, aching joints, and even allergic reactions after eating them.
The Plant Paradox goes so far as to say that lectins are the biggest dietary danger to our health and may even be killing us. Dr. Gundry warns against eating beans, nuts, and many fruits and vegetables, urging us to remove lectins from our diets.
What benefits purportedly come from eating a lectin-free diet? The main claims include improved digestion, more energy, less gas and bloating after eating, better mood and brainpower, and even improved weight control.
Those are some pretty bold promises. So what’s the deal? Are these claims backed up by research? Do we have studies demonstrating that the purported benefits of a lectin-free diet are real?
Let’s look at the science.
For Most People, Most of the Time, Lectin-Rich Foods Are Among the Healthiest You Can Eat
An admission: When I started working on this article, I thought the simple message would be that lectins are great and Dr Gundry is making everything up. But as I dug into the research, I changed my mind. The science on lectins turns out to be genuinely fascinating, and way more nuanced than either Gundry’s alarming claims or a flat dismissal of his concerns would suggest.
A 2024 review in the journal Heliyon took stock of what scientists now know about lectins and the immune system, and it concluded that some lectins — particularly those in soybeans and wheat — can trigger inflammatory pathways in the body. Others, including lectins found in mushrooms and certain flowering plants, appear to do the opposite, calming immune responses and helping to restore balance in the gut.
The review concludes that whether a lectin is harmful or helpful depends heavily on which lectin it is, how much of it you consume, and the specific biological environment it encounters. In other words, the science doesn’t support a one-size-fits-all verdict; lumping all lectins together as either villains or heroes misses the point entirely.
And — a little foreshadowing here — while nuance is good when searching for truth, a message demonizing all lectins turns out to be far more effective at selling supplements.
Here’s what the research shows: Most lectins in properly cooked whole foods are not only harmless for most people but also actively beneficial. Some lectins have such powerful anticancer properties that researchers are investigating them as therapies.
Others, in specific contexts and with specific people, can cause problems.
Let’s start by looking at the “good” lectins and what benefits they can deliver. First, Dr. Gundry gets it right: plant lectins bind to carbohydrates, which slows their digestion. The thing is, this is actually a feature, not a bug.
Lectins can lower the glycemic index of carbohydrates, contributing to the weight loss and anti-diabetes effects of beans and many other plant foods. This may be one reason that high-lectin foods like beans, along with many fruits and vegetables, are among the healthiest foods we can eat. In general, the more you eat, the lower your risk for heart disease, cancer, type 2 diabetes, and Alzheimer’s.
Beans, for example, are rich in many anticancer phytochemicals, which is why they consistently show very powerful associations with lower rates of breast cancer. There’s a type of lectin found in mushrooms that’s been found to inhibit the growth of cancer cells. And, probably not coincidentally, mushrooms are another food offering powerful protection against cancer. Tomatoes are high in lectins as well as the powerful antioxidant lycopene, which has shown extraordinary anticancer effects.
Lectins found in soybeans, bananas, buckwheat, mushrooms, and many other plant foods exhibit such strong anticancer effects that many of them are being investigated as potential cancer therapies.
Lectins may help fight some cancers
A 2017 report published in the International Journal of Molecular Science examined how plant lectins are currently being used to fight cancers of the esophagus, stomach, small intestine, colon, liver, and pancreas. Some lectins are used to detect and diagnose cancer cells. Others are used for therapeutic purposes because of their anti-tumor activity and ability to trigger cancer cell death.
A 2022 paper reviews a lectin called Concanavalin A — the most studied plant lectin — as a potent anti-cancer agent. Researchers report that it can bind to receptors on cancer cells, modulating signaling cascades (kind of like silencing the “grow, grow, grow” chatter in the cells’ group chat), activating immune cells, and killing tumor cells through autophagy and apoptosis across various cancer types.
The journal Cancers even created a 2025 special issue dedicated entirely to “Lectins in Cancer.” (I guess that’s kind of like when People magazine has a special issue like “Cher at 80” or “Michael J Fox: His Inspiring Career”?) The researchers focused on lectin interactions with the tumor microenvironment and how they can be used to diagnose and treat cancer. This is a highly active and growing area of research.
Some people feel better when they avoid lectins
Despite all the apparent benefits of lectins, some people genuinely do report feeling better after cutting out lectin-rich foods. One likely explanation has nothing to do with lectins specifically: Eliminating grains and nightshade vegetables may, for some people, coincide with cutting out processed flour, refined sugar, and calorie-dense packaged foods. And any move away from ultraprocessed foods is likely to drive improvement.
For people with diagnosed autoimmune conditions like rheumatoid arthritis or lupus, a temporary low-lectin elimination trial under the guidance of a registered dietitian may be worth exploring to identify specific triggers.
Not because lectins are inherently dangerous, but because individual biology is real and your experience in your own body matters. For example, people with a compromised gut lining or specific digestive conditions may find that certain lectins cause irritation. In those cases, the issue isn’t that beans or eggplant are inherently harmful, but that the person’s digestive environment may need to be strengthened to digest these foods without gas, bloating, or other issues. This is a real phenomenon that deserves a real answer, and it’s one that a qualified healthcare professional can help you navigate.
(Food Revolution Summit speakers James and Dahlia Marin lead a team of registered dietitians who help people resolve complex gut health issues. You can find out more about their work here.)
Who Should Avoid Lectins?
Despite their potential benefits, there may be people who should avoid lectins, or at least certain lectins, such as the following:
- People with allergies to lectin-containing foods
- People with a digestive sensitivity, such as irritable bowel syndrome or Crohn’s disease
- Possibly people with some autoimmune disorders
As in all things, listen to your own body. You are the only you on the planet. Just because most of the lectin-rich foods are shown, in numerous studies, to be beneficial to human health doesn’t mean they’re necessarily right for all people, all the time — or for you, right now.
A small percentage of the population does have a sensitivity to lectins, just as some people must avoid wheat, corn, fruit, and tree nuts. But one person’s walnut allergy doesn’t mean that another person should refrain from eating walnuts.
If you do notice any side effects after eating lectin-rich foods, then you might have a sensitivity to certain lectins (or to other components of those foods), and you might want to consider reducing or avoiding them — or making sure they’re adequately cooked. There are some people, for example, who don’t do well eating large amounts of raw tomatoes. But they can typically handle abundant pasta sauce and other forms of cooked tomatoes without a problem.
Although eating certain lectins could present difficulties in some situations, it’s highly unlikely that you’re eating a diet high in uncooked or undercooked lectins of the problematic variety. I don’t know anyone who reaches for a handful of raw, uncooked kidney beans when their stomach starts rumbling.
The Truth About Lectin Toxicity
Given all that overwhelming evidence in favor of common lectin-containing foods, what evidence does Dr. Gundry marshal to support his claim that lectins are the Devil’s proteins? (He doesn’t refer to them in those words, but I think it’s a pretty catchy phrase. Looks like I missed my calling as an anti-lectin marketer!)
In some cases, it’s a flimsy case of guilt by association.
Dr. Gundry and his fellow “lectophobes” (I’m pretty sure I just made that word up) like to point out that one of the lectins found in castor beans, a compound called ricin, is one of the deadliest poisons ever discovered. Apparently, Russian hitmen like to inject it into the bloodstreams of their victims (sometimes with special, spring-loaded umbrella guns). The assassin casually walks away, and the recipient of the injection dies within 48 hours.
It’s not just castor beans that can deliver a toxic dose of lectins (with or without a spring-loaded umbrella). Raw kidney beans contain a lectin called phytohaemagglutinin, which causes unpleasant digestive symptoms (extreme nausea, severe vomiting, abdominal pain, diarrhea) when consumed. Eating just four or five raw beans can trigger those symptoms.
The important distinction is between lectins in raw or seriously undercooked food, where toxicity is real and well-documented, and lectins in properly prepared whole foods, where the picture is almost entirely positive for most people.
For example, raw kidney beans contain 20,000 to 70,000 hemagglutinating units (abbreviated hau, and used as a measure of toxicity), while properly cooked kidney beans contain just 200–400 (1,000+ times less!).
These are not the same thing, and treating them as if they were is one of the main sleights of hand in the anti-lectin argument.
Most Lectins Are Beneficial in Small Amounts
You might be thinking, “Well, if some lectins are pro-inflammatory, and others are used by Russian assassins, should I just steer clear?” After all, if the evolutionary purpose of lectins is to create “plant poisons” to prevent them from predation, why would you want to poison yourself?
The answer becomes clear when we look at the other phytonutrients: compounds in plants that are really good for us (and often indispensable to our health). It’s actually the mild stress of a tiny amount of “poison” that triggers healing responses in our bodies. Kind of like the stress of lifting heavy weights that makes our muscle fibers respond by growing stronger.
The fancy name for good stress that forces us to grow stronger is “hormesis.” Without experiencing regular doses of hormesis in the form of small, manageable challenges, we become fragile to our environments and do not thrive. The keywords here are small and manageable.
If you look up hormesis in a scientific textbook, you’ll see a bunch of graphs shaped like the letters U or J that illustrate the dose-response nature of the phenomenon. That is, a small amount of some toxins is actually good for you, while a larger dose is not. And a large enough dose (like that contained in killer KGB umbrellas) will kill you.
That’s one part of the answer to Dr. Gundry’s so-called “Plant Paradox.” The other part is that not all lectins behave the same way, which means the solution isn’t to avoid all lectin-containing foods, but to understand which ones work for your particular body and the best ways to prepare them.
Reducing Lectins in Food
Now, you might be worried about your daily lectin intake. How can you be sure you’re not getting too much and drifting into KGB umbrella territory through your irresponsibly enthusiastic consumption of lentils, eggplant, and barley?
Luckily, most lectins are completely neutralized by cooking. Yes, eating a bunch of raw kidney beans will give you a miserable case of vomiting and diarrhea. But before that happens, eating raw kidney beans will give you a miserable case of broken teeth. So why on earth would you be eating raw or seriously undercooked kidney beans?
The uncooked bean argument favored by lectophobes is a straw man; cook the beans, and the lectins are rendered utterly harmless to most people. In fact, even Dr. Gundry concedes that when beans are pressure-cooked (as all canned beans are), they’re pretty safe.
The problem with this admission is that it can still mislead people into thinking that legumes are dangerous and must be processed with all the care and attention generally reserved for a half-pound of plutonium. The truth is, beans are a staple of some of the longest-lived people on earth. And I’m pretty confident that Sardinian peasants and Okinawan farmers haven’t been using Instant Pots to neutralize their lectins for the past hundred years.
If you want to be thorough about reducing lectins in your cooking, here’s what works: soak your legumes before cooking them. This leaches lectins into the soaking water, so you should discard it rather than cook with it. It also activates germination if you soak them long enough (at least 24 hours), making the nutrients in your beans more bioavailable.
To neutralize the remaining lectins (those really stubborn ones, I guess), pressure cook those legumes. As we’ve seen, canned beans, which are pressure-cooked, are essentially lectin-free.
Another way to handle lectins is to ferment or sprout grains and legumes. These methods naturally break down lectins as they progress.
And remember: For most commonly eaten foods prepared with standard cooking methods, lectin levels are not a meaningful concern for most people.
What the Broader Scientific Community Says
Given the paucity of evidence for Dr. Gundry’s argument, and the fact that The Plant Paradox is adding fuel to our already raging fire of obesity, diabetes, and heart disease by discouraging people from eating some of the most protective foods on the planet, I don’t want to portray this as just another vigorous debate among thoughtful scientists.
To understand the anti-lectin movement, you need to follow the money.
Dr. Gundry’s solution to the Plant Paradox is a suite of supplements and programs — a lectin shield, a range of “must-have” products, and various membership offerings. His widely aired infomercials and marketing campaigns aren’t free. It would seem likely that his company is recouping its investment through high-volume repeat sales.
A nuanced, individualized message about which lectins matter for which people in which contexts doesn’t sell supplements. A simple villain narrative (“lectins are deadly and these pills and powders will protect you”) does. When the science is genuinely complex, it’s worth asking who benefits most from flattening it into something scary and simple.
Yes, some people should limit their exposure to lectins. But I think that the vast majority of us should probably dismiss Dr. Gundry’s assertions out of hand. The truth is that the foods Dr. Gundry warns against are among the most studied, most protective foods in the human diet. Telling people to avoid them has real consequences.
Should You Eat Lectins?
The evidence is clear. For most people, properly prepared lectin-rich whole foods are among the most powerful disease-fighting foods available. These foods provide plenty of vitamins, minerals, and other nutrients that are great for human health. When it comes to adverse reactions to eating lectins, most people don’t experience these as long as cooking methods are adequate. Soaking and cooking legumes can minimize the potential side effects.
I’ve seen a lot of nutritional nonsense, but I have to say that telling people to avoid plant foods such as beans, berries, and tomatoes because they contain lectins strikes me as generally (though not always) terrible advice. Here we are, with soaring rates of chronic diseases that are clearly linked to eating too many low-nutrient, low-fiber, sugar-enhanced, heavily processed foods, yet we’re being warned against eating some of the healthiest foods on the planet.
My advice? Don’t buy the oversimplification in either direction. The science on lectins is genuinely interesting and shows that most lectin-rich whole foods, properly prepared, are among the most powerful disease-fighting foods available to us.
For most people, most of the time, beans, tomatoes, berries, and whole grains are not the problem. They’re a big part of the solution.
If you have specific digestive or autoimmune conditions, work with a clinician to figure out what works for your body. And if someone is selling you a supplement to solve a problem that cooking your beans already solves for free, be a little skeptical.
Tell us in the comments:
- What do you think?
- Do you eat lectins? Why or why not?
Featured Image: iStock.com/malerapaso
