Lectins are proteins found in around 30 percent of the foods you eat, such as legumes, peanuts, lentils, tomatoes, potatoes, eggplant, fruits, and wheat. While there are some toxins in these foods (specifically in foods like raw kidney beans), the cooking process denatures the lectins, meaning they are harmless. There is no evidence to suggest that lectins are the cause of chronic disease or obesity.
There's a book called The Plant Paradox, which asserts a very strong claim: lectins are the cause of many health issues. For most people, "lectins" is a foreign word, but they are not found in foreign foods. Lectins are proteins found in around 30 percent of the foods we eat, including many friends and vegetables, whole grains, nuts, and beans.
The book suggests that lectins are toxic and, even in low doses, lectins can cause long-term health effects like chronic disease and inflammation.
Before we address the claims, it's important to understand a little more about lectins. After all, if they are so dangerous and found in common foods, why wasn't this identified earlier?
What are Lectins?
Plants naturally produce lectins as a defense mechanism. Lectins can cause significant gastrointestinal distress in humans when they’re consumed in raw foods, but they’re mostly denatured by proper cooking.
This is why you can get severely ill from eating raw kidney beans, but not from canned kidney beans. The cooking process has denatured the lectins in the canned beans, rendering them harmless (the beans and the lectins). Just so you're clear: lectins aren’t generally a problem unless you’re eating raw kidney beans or raw grains (crunch crunch…um, no).
Other common lectin-containing foods are nightshade vegetables, pulses, and grains, and seeds, like quinoa and chia. While it's fair to say that some people don't tolerate lectin-containing foods as well as others, I disagree with the suggestion that nobody should be eating them.
Is There Any Real Danger?
As with most pseudoscientific fairytales, this one starts with a kernel of truth. Just a kernel, mind you.
As you can imagine, lectins have been around as long as humans have and we’re still here. We’re also getting sicker, not healthier, even though the overall consumption of beans, fruits, and vegetables worldwide has decreased. So, on the surface, it's hard to make the claim that lectins are the cause when people are eating less of them. But, that's just the start of the flawed reasoning.
The healthiest, longest-living people on earth, who live in the Blue Zones, eat a plant-rich diet. And, they don’t avoid soy or other lectin-containing foods. The Plant Paradox's answer to that? The antioxidants in the other foods they eat counteract the lectins. The problem: there's zero science that backs up this claim. If so, why not just push a high-antioxidant diet rather than a low lectin diet?
If you keep going down the rabbit hole, the claims look harder and harder to believe. Chickpeas have been cultivated since at least 3200 BC, and lentils enjoyed for at least 8000 years. If they’re toxic, why haven’t we learned not to eat them?
Aztecs used tomatoes in their cooking. Doesn’t it strike you as strange that these civilizations grew and prospered and we have continued to eat these foods through to modern days?
We’ve evolved to not get sick from lectins and to cook food to denature any dangers. If lectins were so dangerous, then why do we have a higher incidence of chronic disease than countries such as Greece and Italy, where they commonly eat legumes, grains, and nightshades as part of their diets?
The current obsession with ‘toxic’ foods is based on fear. Fear sells, right? If you can put aside that fear for just a moment and reflect on the well-researched fact that a mostly plant-based diet appears to promote health and prevent disease, it's easy to conclude that the majority of people are not at risk from eating lectins.
Who Should Avoid Lectins?
Many fad diets have made the same ‘toxic’ claim against lectins, but it's twisted science. That said, some people can benefit from avoiding lectins, just as there are people with gluten allergies who should avoid gluten.
If you have has dysfunctional enzymes, then lectins may cause autoimmune issues for you as they may compromise your intestinal barrier. It’s entirely probable that autoimmune diseases such as rheumatoid arthritis are related in part to dietary factors, and lectins could be one of them.
If you have an autoimmune disease or a digestive disease such as IBD, you may feel better by eliminating lectins from your diet...or you may not. Even if removing them helps with your symptoms, you probably don’t have to eliminate all lectin-containing foods: An elimination diet can reveal which ones cause you issues, and which ones don’t.
Turning a problem for a very small, specific audience into a huge deal about how lectins are making everyone sick is a dangerous dietary approach.
The book also recommends only grass-fed and pastured meats because feed grains have toxic lectins (which supposedly get into the animal’s flesh and subsequently into our system once we eat it). The problem: that mechanism is pretty far-fetched and not at all proven.
How To Assess Any Diet
The fear of lectins is not an isolated incident. Hopefully, you've seen that -- unless you meet some specific medical needs -- there's no danger to eating lectins. The bigger concern is being able to assess new diets and determine what is the best fit for you.
As a dietitian, I want to see compelling evidence behind a diet before recommending it to my clients and to the public. The Plant Paradox is based on the shoddiest research available, and, by that, I mean it's embarrassing.
Many of the studies that are cited in the book don’t support the claims at all. Many of them have a faulty methodology or are extremely small - like 10 people. Or, they’re rodent studies or worse, studies done on cells in a lab. These types of studies do not prove anything in relation to humans. It’s all theoretical.
In order to navigate the confusing world of dieting, here is a quick checklist that can help you make more informed decisions.
Scare tactics: The foods you’ve thought were healthy - PLANTS! - are TOXIC!! OH MY GOD!
A personal transformation: As in, I lost 70 pounds and now want to share will all of you how I did it! That makes me a nutrition expert! (Editor's Note: personal transformations are great! But, don't buy into the one-size-fits-all-and-solves-all-problems mentality. That's a slippery slope.)
Promises with no human research to back them up: Eat this diet, and you’ll get rid of everything that ails you, including diseases such as cancer and multiple sclerosis.
Expensive food requirements
Twisted science: For instance, forgetting to add that not everyone reacts to lectins and that plant-based diets have consistently been proven to be beneficial, not harmful.
The promise of a huge reveal: As in, you’ll be part of a special club that knows the secret to weight loss/health/etc. that other people don’t know.
I know that some of you will read this review and be upset. Some might message me and say that I’m wrong and that this diet has helped you. I know that some of you will never have your minds changed by anything I write, and that’s okay.
If you try this diet and find that your health issues resolve, that’s good! But, I want you to understand that any resolution of your problems is independent of the irresponsible blanket statement that lectins are toxic for everyone.
The resolution of your symptoms and any weight loss that may occur may be because The Plant Paradox forbids a huge number of foods that you may otherwise be eating, and it appears to also be restrictive and low in calories. It may not be because you took lectins out of your diet.
When you stop eating certain ingredients that are in pretty much every junk food, you’re sure to lose weight, but you’ll probably be miserable if you do it long-term. Because good nutrition sometimes includes cake. And pizza. And enjoying meals with friends and family without being anxious about what you’re eating.
The Plant Paradox uses scare tactics to sell its concept. It perpetuates unproven, inaccurate beliefs about ‘toxins’ in our diets. The truth is that most people don't eat enough plants, and it's irresponsible to scare people away from foods that are the foundation of healthy habits.